Electric Power System

Electric power system From Wikipedia, the free encyclopedia

A steam turbine used to provide electric power.

An electric power system is a network of electrical components used to supply, transmit and use electric power. An example of an electric power system is the network that supplies a region's homes and industry with power—for sizable regions, this power system is known as the grid and can be broadly divided into the generators that supply the power, the transmission system that carries the power from the generating centres to the load centres and the distribution system that feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings and homes. The majority of these systems rely upon three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialised power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles. Contents [hide]

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1 History

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2 Basics of electric power

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3 Balancing the grid

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4 Components of power systems o

4.1 Supplies

o

4.2 Loads

o

4.3 Conductors

o

4.4 Capacitors and reactors

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4.5 Power electronics

o

4.6 Protective devices

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4.7 SCADA systems

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5 Power systems in practice o

5.1 Residential power systems

o

5.2 Commercial power systems

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6 References

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7 External links

History[edit]

A sketch of the Pearl Street Station

In 1881 two electricians built the world's first power system at Godalming in England. It was powered by a power station consisting of two waterwheels that produced an alternating current that in turn supplied seven Siemens arc lamps at 250 volts and 34 incandescent lamps at 40 volts.[1] However supply to the lamps was intermittent and in 1882 Thomas Edison and his company, The Edison Electric Light Company, developed the first steam powered electric power station on Pearl Street in New York City. The Pearl Street Station initially powered around 3,000 lamps for 59 customers.[2][3] The power station used direct current and operated at a single voltage. Direct current power could not be easily transformed to the higher voltages necessary to minimise power loss during long-distance transmission, so the maximum economic distance between the generators and load was limited to around half-a-mile (800 m). [4] That same year in London Lucien Gaulard and John Dixon Gibbs demonstrated the first transformer suitable for use in a real power system. The practical value of Gaulard and Gibbs' transformer was demonstrated in 1884 at Turin where the transformer was used to light up forty kilometres (25 miles) of railway from a single alternating current generator.[5] Despite the success of the system, the pair made some fundamental mistakes. Perhaps the most serious was connecting the primaries of the transformers in series so that active lamps would affect the brightness of other lamps further down the line. Following the demonstration George Westinghouse, an American entrepreneur, imported a number of the transformers along with a Siemens generator and set his engineers to experimenting with them in the hopes of improving them for use in a commercial power system. In July 1888, Westinghouse also licensed Nikola Tesla's US patents for a polyphase AC induction motor and transformer designs and hired Tesla for one year to be a consultant at the Westinghouse Electric & Manufacturing Company's Pittsburgh labs.[6]

One of Westinghouse's engineers, William Stanley, recognised the problem with connecting transformers in series as opposed to parallel and also realised that making the iron core of a transformer a fully enclosed loop would improve the voltage regulation of the secondary winding. Using this knowledge he built a much improved alternating current power system at Great Barrington, Massachusetts in 1886.[7] By 1890 the electric power industry was flourishing, and power companies had built thousands of power systems (both direct and alternating current) in the United States and Europe. These networks were effectively dedicated to providing electric lighting. During this time a fierce rivalry known as the "War of Currents" emerged between Thomas Edison and George Westinghouse over which form of transmission (direct or alternating current) was superior.[8] In 1891, Westinghouse installed the first major power system that was designed to drive a 100 horsepower (75 kW) synchronous electric motor, not just provide electric lighting, at Telluride, Colorado.[9] On the other side of the Atlantic, Oskar von Miller built a 20 kV 176 km three-phase transmission line from Lauffen am Neckar to Frankfurt am Main for the Electrical Engineering Exhibition in Frankfurt.[10] In 1895, after a protracted decision-making process, the Adams No. 1 generating station at Niagara Falls began transferring three-phase alternating current power to Buffalo at 11 kV. Following completion of the Niagara Falls project, new power systems increasingly chose alternating current as opposed to direct current for electrical transmission.[11] Developments in power systems continued beyond the nineteenth century. In 1936 the first experimental HVDC (high voltage direct current) line using mercury arc valves was built between Schenectady and Mechanicville, New York. HVDC had previously been achieved by series-connected direct current generators and motors (the Thury system) although this suffered from serious reliability issues.[12] In 1957 Siemens demonstrated the first solid-state rectifier, but it was not until the early 1970s that solid-state devices became the standard in HVDC. [13] In recent times, many important developments have come from extending innovations in the ICT field to the power engineering field. For example, the development of computers meant load flow studies could be run more efficiently allowing for much better planning of power systems. Advances in information technology and telecommunication also allowed for remote control of a power system's switchgear and generators.

Basics of electric power[edit]

An external AC to DC power adapter used for household appliances

Electric power is the product of two quantities: current and voltage. These two quantities can vary with respect to time (AC power) or can be kept at constant levels (DC power). Most refrigerators, air conditioners, pumps and industrial machinery use AC power whereas most computers and digital equipment use DC power (the digital devices you plug into the mains typically have an internal or external power adapter to convert from AC to DC power). AC power has the advantage of being easy to transform between voltages and is able to be generated and utilised by brushless machinery. DC power remains the only practical choice in digital systems and can be more economical to transmit over long distances at very high voltages (see HVDC).[14] [15]

The ability to easily transform the voltage of AC power is important for two reasons: Firstly, power can be transmitted over long distances with less loss at higher voltages. So in power systems

where generation is distant from the load, it is desirable to step-up (increase) the voltage of power at the generation point and then step-down (decrease) the voltage near the load. Secondly, it is often more economical to install turbines that produce higher voltages than would be used by most appliances, so the ability to easily transform voltages means this mismatch between voltages can be easily managed.[14] Solid state devices, which are products of the semiconductor revolution, make it possible to transform DC power to different voltages, build brushless DC machines and convert between AC and DC power. Nevertheless devices utilising solid state technology are often more expensive than their traditional counterparts, so AC power remains in widespread use. [16]

Balancing the grid[edit] One of the main difficulties in power systems is that the amount of active power consumed plus losses should always equal the active power produced. If more power would be produced than consumed the frequency would rise and vice versa. Even small deviations from the nominal frequency value would damage synchronous machines and other appliances. Making sure the frequency is constant is usually the task of a transmission system operator. In some countries (for example in the European Union) this is achieved through a balancing market using ancillary services.[17]

Components of power systems[edit] Supplies[edit]

The majority of the world's power still comes from coal-fired power stations like this.

All power systems have one or more sources of power. For some power systems, the source of power is external to the system but for others it is part of the system itself—it is these internal power sources that are discussed in the remainder of this section. Direct current power can be supplied by batteries, fuel cells or photovoltaic cells. Alternating current power is typically supplied by a rotor that spins in a magnetic field in a device known as a turbo generator. There have been a wide range of techniques used to spin a turbine's rotor, from steam heated using fossil fuel (including coal, gas and oil) or nuclear energy, falling water (hydroelectric power) and wind (wind power). The speed at which the rotor spins in combination with the number of generator poles determines the frequency of the alternating current produced by the generator. All generators on a single synchronous system, for example the national grid, rotate at sub-multiples of the same speed and so generate electrical current at the same frequency. If the load on the system increases, the generators will require more torque to spin at that speed and, in a typical power station, more steam must be supplied to the turbines driving them. Thus the steam used and the fuel expended are directly dependent on the quantity of electrical energy supplied. An exception exists for generators incorporating power electronics such as gearless wind turbines or linked to a grid through an asynchronous tie such as a HVDC link — these can operate at frequencies independent of the power system frequency.

Depending on how the poles are fed, alternating current generators can produce a variable number of phases of power. A higher number of phases leads to more efficient power system operation but also increases the infrastructure requirements of the system. [18] Electricity grid systems connect multiple generators and loads operating at the same frequency and number of phases, the commonest being three-phase at 50 or 60 Hz. However there are other considerations. These range from the obvious: How much power should the generator be able to supply? What is an acceptable length of time for starting the generator (some generators can take hours to start)? Is the availability of the power source acceptable (some renewables are only available when the sun is shining or the wind is blowing)? To the more technical: How should the generator start (some turbines act like a motor to bring themselves up to speed in which case they need an appropriate starting circuit)? What is the mechanical speed of operation for the turbine and consequently what are the number of poles required? What type of generator is suitable (synchronous or asynchronous) and what type of rotor (squirrel-cage rotor, wound rotor, salient pole rotor or cylindrical rotor)?[19]

Loads[edit]

A toaster is great example of a single-phase load that might appear in a residence. Toasters typically draw 2 to 10 amps at 110 to 260 volts consuming around 600 to 1200 watts of power

Power systems deliver energy to loads that perform a function. These loads range from household appliances to industrial machinery. Most loads expect a certain voltage and, for alternating current devices, a certain frequency and number of phases. The appliances found in your home, for example, will typically be single-phase operating at 50 or 60 Hz with a voltage between 110 and 260 volts (depending on national standards). An exception exists for centralized air conditioning systems as these are now typically three-phase because this allows them to operate more efficiently. All devices in your house will also have a wattage, this specifies the amount of power the device consumes. At any one time, the net amount of power consumed by the loads on a power system must equal the net amount of power produced by the supplies less the power lost in transmission.[20][21] Making sure that the voltage, frequency and amount of power supplied to the loads is in line with expectations is one of the great challenges of power system engineering. However it is not the only challenge, in addition to the power used by a load to do useful work (termed real power) many alternating current devices also use an additional amount of power because they cause the alternating voltage and alternating current to become slightly out-of-sync (termed reactive power). The reactive power like the real power must balance (that is the reactive power produced on a system must equal the reactive power consumed) and can be supplied from the generators, however it is often more economical to supply such power from capacitors (see "Capacitors and reactors" below for more details).[22] A final consideration with loads is to do with power quality. In addition to sustained overvoltages and undervoltages (voltage regulation issues) as well as sustained deviations from the system frequency (frequency regulation issues), power system loads can be adversely affected by a range of temporal issues. These include voltage sags, dips and swells, transient overvoltages, flicker, high frequency noise, phase imbalance and poor power factor.[23] Power quality issues occur when the power supply to a load deviates from the ideal: For an AC supply, the ideal is the current and voltage in-sync fluctuating as a perfect sine wave at a prescribed frequency with the

voltage at a prescribed amplitude. For DC supply, the ideal is the voltage not varying from a prescribed level. Power quality issues can be especially important when it comes to specialist industrial machinery or hospital equipment.

Conductors[edit] Conductors carry power from the generators to the load. In a grid, conductors may be classified as belonging to the transmission system, which carries large amounts of power at high voltages (typically more than 69 kV) from the generating centres to the load centres, or the distribution system, which feeds smaller amounts of power at lower voltages (typically less than 69 kV) from the load centres to nearby homes and industry.[24] Choice of conductors is based upon considerations such as cost, transmission losses and other desirable characteristics of the metal like tensile strength. Copper, with lower resistivity than aluminium, was the conductor of choice for most power systems. However, aluminum has lower cost for the same current carrying capacity and is the primary metal used for transmission line conductors. Overhead line conductors may be reinforced with steel or aluminum alloys.[25] Conductors in exterior power systems may be placed overhead or underground. Overhead conductors are usually air insulated and supported on porcelain, glass or polymer insulators. Cables used for underground transmission or building wiring are insulated with cross-linked polyethylene or other flexible insulation. Large conductors are stranded for ease of handling; small conductors used for building wiring are often solid, especially in light commercial or residential construction.[26] Conductors are typically rated for the maximum current that they can carry at a given temperature rise over ambient conditions. As current flow increases through a conductor it heats up. For insulated conductors, the rating is determined by the insulation. [27] For overhead conductors, the rating is determined by the point at which the sag of the conductors would become unacceptable.[28]

Capacitors and reactors[edit] The majority of the load in a typical AC power system is inductive; the current lags behind the voltage. Since the voltage and current are out-of-phase, this leads to the emergence of an "imaginary" form of power known as reactive power. Reactive power does no measurable work but is transmitted back and forth between the reactive power source and load every cycle. This reactive power can be provided by the generators themselves, through the adjustment of generator excitation, but it is often cheaper to provide it through capacitors, hence capacitors are often placed near inductive loads to reduce current demand on the power system (i.e., increase the power factor), which may never exceed 1.0, and which represents a purely resistive load. Power factor correction may be applied at a central substation, through the use of so-called "synchronous condensers" (synchronous machines which act as condensers which are variable in VAR value, through the adjustment of machine excitation) or adjacent to large loads, through the use of so-called "static condensers" (condensers which are fixed in VAR value). Reactors consume reactive power and are used to regulate voltage on long transmission lines. In light load conditions, where the loading on transmission lines is well below thesurge impedance loading, the efficiency of the power system may actually be improved by switching in reactors. Reactors installed in series in a power system also limit rushes of current flow, small reactors are therefore almost always installed in series with capacitors to limit the current rush associated with switching in a capacitor. Series reactors can also be used to limit fault currents. Capacitors and reactors are switched by circuit breakers, which results in moderately large steps in reactive power. A solution comes in the form of static VAR compensators andstatic synchronous compensators. Briefly, static VAR compensators work by switching in capacitors using thyristors as opposed to circuit breakers allowing capacitors to be switched-in and switched-out within a single cycle. This provides a far more refined response than circuit breaker switched capacitors. Static synchronous compensators take a step further by achieving reactive power adjustments using only power electronics.

Power electronics[edit]

Power electronics are semi-conductor based devices that are able to switch quantities of power ranging from a few hundred watts to several hundred megawatts. Despite their relatively simple function, their speed of operation (typically in the order of nanoseconds [29]) means they are capable of a wide range of tasks that would be difficult or impossible with conventional technology. The classic function of power electronics is rectification, or the conversion of AC-toDC power, power electronics are therefore found in almost every digital device that is supplied from an AC source either as an adapter that plugs into the wall (see photo in Basics of Electric Power section) or as component internal to the device. High-powered power electronics can also be used to convert AC power to DC power for long distance transmission in a system known as HVDC. HVDC is used because it proves to be more economical than similar high voltage AC systems for very long distances (hundreds to thousands of kilometres). HVDC is also desirable for interconnects because it allows frequency independence thus improving system stability. Power electronics are also essential for any power source that is required to produce an AC output but that by its nature produces a DC output. They are therefore used by many photovoltaic installations both industrial and residential. Power electronics also feature in a wide range of more exotic uses. They are at the heart of all modern electric and hybrid vehicles—where they are used for both motor control and as part of the brushless DC motor. Power electronics are also found in practically all modern petrolpowered vehicles, this is because the power provided by the car's batteries alone is insufficient to provide ignition, air-conditioning, internal lighting, radio and dashboard displays for the life of the car. So the batteries must be recharged while driving using DC power from the engine—a feat that is typically accomplished using power electronics. Whereas conventional technology would be unsuitable for a modern electric car, commutators can and have been used in petrolpowered cars, the switch to alternators in combination with power electronics has occurred because of the improved durability of brushless machinery.[30] Some electric railway systems also use DC power and thus make use of power electronics to feed grid power to the locomotives and often for speed control of the locomotive's motor. In the middle twentieth century, rectifier locomotives were popular, these used power electronics to convert AC power from the railway network for use by a DC motor.[31]Today most electric locomotives are supplied with AC power and run using AC motors, but still use power electronics to provide suitable motor control. The use of power electronics to assist with motor control and with starter circuits cannot be underestimated and, in addition to rectification, is responsible for power electronics appearing in a wide range of industrial machinery. Power electronics even appear in modern residential air conditioners. Power electronics are also at the heart of the variable speed wind turbine. Conventional wind turbines require significant engineering to ensure they operate at some ratio of the system frequency, however by using power electronics this requirement can be eliminated leading to quieter, more flexible and (at the moment) more costly wind turbines. A final example of one of the more exotic uses of power electronics comes from the previous section where the fastswitching times of power electronics were used to provide more refined reactive compensation to the power system.

Protective devices[edit] Main article: power system protection Power systems contain protective devices to prevent injury or damage during failures. The quintessential protective device is the fuse. When the current through a fuse exceeds a certain threshold, the fuse element melts, producing an arc across the resulting gap that is then extinguished, interrupting the circuit. Given that fuses can be built as the weak point of a system, fuses are ideal for protecting circuitry from damage. Fuses however have two problems: First, after they have functioned, fuses must be replaced as they cannot be reset. This can prove inconvenient if the fuse is at a remote site or a spare fuse is not on hand. And second, fuses are typically inadequate as the sole safety device in most power systems as they allow current flows well in excess of that that would prove lethal to a human or animal. The first problem is resolved by the use of circuit breakers—devices that can be reset after they have broken current flow. In modern systems that use less than about 10 kW, miniature circuit

breakers are typically used. These devices combine the mechanism that initiates the trip (by sensing excess current) as well as the mechanism that breaks the current flow in a single unit. Some miniature circuit breakers operate solely on the basis of electromagnetism. In these miniature circuit breakers, the current is run through a solenoid, and, in the event of excess current flow, the magnetic pull of the solenoid is sufficient to force open the circuit breaker's contacts (often indirectly through a tripping mechanism). A better design however arises by inserting a bimetallic strip before the solenoid—this means that instead of always producing a magnetic force, the solenoid only produces a magnetic force when the current is strong enough to deform the bimetallic strip and complete the solenoid's circuit. In higher powered applications, the protective relays that detect a fault and initiate a trip are separate from the circuit breaker. Early relays worked based upon electromagnetic principles similar to those mentioned in the previous paragraph, modern relays are application-specific computers that determine whether to trip based upon readings from the power system. Different relays will initiate trips depending upon different protection schemes. For example, an overcurrent relay might initiate a trip if the current on any phase exceeds a certain threshold whereas a set of differential relays might initiate a trip if the sum of currents between them indicates there may be current leaking to earth. The circuit breakers in higher powered applications are different too. Air is typically no longer sufficient to quench the arc that forms when the contacts are forced open so a variety of techniques are used. One of the most popular techniques is to keep the chamber enclosing the contacts flooded with sulfur hexafluoride (SF6)— a non-toxic gas that has sound arc-quenching properties. Other techniques are discussed in the reference.[32] The second problem, the inadequacy of fuses to act as the sole safety device in most power systems, is probably best resolved by the use of residual current devices (RCDs). In any properly functioning electrical appliance the current flowing into the appliance on the active line should equal the current flowing out of the appliance on the neutral line. A residual current device works by monitoring the active and neutral lines and tripping the active line if it notices a difference. [33] Residual current devices require a separate neutral line for each phase and to be able to trip within a time frame before harm occurs. This is typically not a problem in most residential applications where standard wiring provides an active and neutral line for each appliance (that's why your power plugs always have at least two tongs) and the voltages are relatively low however these issues do limit the effectiveness of RCDs in other applications such as industry. Even with the installation of an RCD, exposure to electricity can still prove lethal.

SCADA systems[edit] In large electric power systems, Supervisory Control And Data Acquisition (SCADA) is used for tasks such as switching on generators, controlling generator output and switching in or out system elements for maintenance. The first supervisory control systems implemented consisted of a panel of lamps and switches at a central console near the controlled plant. The lamps provided feedback on the state of plant (the data acquisition function) and the switches allowed adjustments to the plant to be made (the supervisory control function). Today, SCADA systems are much more sophisticated and, due to advances in communication systems, the consoles controlling the plant no longer need to be near the plant itself. Instead it is now common for plant to be controlled from a with equipment similar to (if not identical to) a desktop computer. The ability to control such plant through computers has increased the need for security and already there have been reports of cyber-attacks on such systems causing significant disruptions to power systems.[34]

Power systems in practice[edit] Despite their common components, power systems vary widely both with respect to their design and how they operate. This section introduces some common power system types and briefly explains their operation.

Residential power systems[edit]

Residential dwellings almost always take supply from the low voltage distribution lines or cables that run past the dwelling. These operate at voltages of between 110 and 260 volts (phase-toearth) depending upon national standards. A few decades ago small dwellings would be fed a single phase using a dedicated two-core service cable (one core for the active phase and one core for the neutral return). The active line would then be run through a main isolating switch in the fuse box and then split into one or more circuits to feed lighting and appliances inside the house. By convention, the lighting and appliance circuits are kept separate so the failure of an appliance does not leave the dwelling's occupants in the dark. All circuits would be fused with an appropriate fuse based upon the wire size used for that circuit. Circuits would have both an active and neutral wire with both the lighting and power sockets being connected in parallel. Sockets would also be provided with a protective earth. This would be made available to appliances to connect to any metallic casing. If this casing were to become live, the theory is the connection to earth would cause an RCD or fuse to trip—thus preventing the future electrocution of an occupant handling the appliance. Earthing systems vary between regions, but in countries such as the United Kingdom and Australia both the protective earth and neutral line would be earthed together near the fuse box before the main isolating switch and the neutral earthed once again back at the distribution transformer.[35] There have been a number of minor changes over the year to practice of residential wiring. Some of the most significant ways modern residential power systems tend to vary from older ones include: 

For convenience, miniature circuit breakers are now almost always used in the fuse box instead of fuses as these can easily be reset by occupants.

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For safety reasons, RCDs are now installed on appliance circuits and, increasingly, even on lighting circuits.

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Dwellings are typically connected to all three-phases of the distribution system with the phases being arbitrarily allocated to the house's single-phase circuits.

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Whereas air conditioners of the past might have been fed from a dedicated circuit attached to a single phase, centralised air conditioners that require three-phase power are now becoming common.

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Protective earths are now run with lighting circuits to allow for metallic lamp holders to be earthed.

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Increasingly residential power systems are incorporating microgenerators, most notably, photovoltaic cells.

Commercial power systems[edit] Commercial power systems such as shopping centers or high-rise buildings are larger in scale than residential systems. Electrical designs for larger commercial systems are usually studied for load flow, short-circuit fault levels, and voltage drop for steady-state loads and during starting of large motors. The objectives of the studies are to assure proper equipment and conductor sizing, and to coordinate protective devices so that minimal disruption is cause when a fault is cleared. Large commercial installations will have an orderly system of sub-panels, separate from the main distribution board to allow for better system protection and more efficient electrical installation. Typically one of the largest appliances connected to a commercial power system is the HVAC unit, and ensuring this unit is adequately supplied is an important consideration in commercial power systems. Regulations for commercial establishments place other requirements on commercial systems that are not placed on residential systems. For example, in Australia, commercial systems must comply with AS 2293, the standard for emergency lighting, which requires emergency lighting be maintained for at least 90 minutes in the event of loss of mains

supply.[36] In the United States, the National Electrical Code requires commercial systems to be built with at least one 20A sign outlet in order to light outdoor signage. [37] Building code regulations may place special requirements on the electrical system for emergency lighting, evacuation, emergency power, smoke control and fire protection. A thermodynamic system is the content of a macroscopic volume in space, along with its walls and surroundings; it undergoesthermodynamic processes according to the principles of thermodynamics. A physical system qualifies as a thermodynamic system only if it can be adequately described by thermodynamic variables such as temperature, entropy, internal energy and pressure. The thermodynamic state of a thermodynamic system is its internal state as specified by its state variables. A thermodynamic account also requires a special kind of function called a state function. For example, if the state variables are internal energy, volume and mole amounts, the needed further state function is entropy. These quantities are inter-related by one or more functional relationships called equations of state. Thermodynamics defines the restrictions on the possible equations of state imposed by the laws of thermodynamics through that further function of state. The system is delimited by walls or boundaries, either actual or notional, across which conserved (such as matter and energy) or unconserved (such as entropy) quantities can pass into and out of the system. The space outside the thermodynamic system is known as thesurroundings, a reservoir, or the environment. The properties of the walls determine what transfers can occur. A wall that allows transfer of a quantity is said to be permeable to it, and a thermodynamic system is classified by the permeabilities of its several walls. A transfer between system and surroundings can arise by contact, such as conduction of heat, or by long-range forces such as an electric field in the surroundings.

by types of wall Types of transfers permitted

type of transfer

type of wall Mass

and energy

Work

Heat

permeable to matter permeable to energy but impermeable to matter adiabatic adynamic and impermeable to matter isolating A system with walls that prevent all transfers is said to be isolated. This is an idealized conception, because in practice some transfer is always possible, for example by gravitational forces. It is an axiom of thermodynamics that an isolated system eventually reaches internal thermodynamic equilibrium, when its state no longer changes with time. According to the permeabilities of its walls, a system that is not isolated can be in thermodynamic equilibrium with its surroundings, or else may be in a state that is constant or precisely cyclically changing in time - a steady state that is far from equilibrium. Classical thermodynamics considers only states of thermodynamic systems in equilibrium that are either constant or precisely cycling in time. The walls of a closed system allow transfer of energy as heat and as work, but not of matter, between it and its surroundings. The walls of an open system allow transfer both of matter and of energy.[1][2][3][4][5][6][7] This scheme of definition of terms is not uniformly used, though it is convenient for some purposes. In particular, some writers use 'closed system' where 'isolated system' is here used.[8][9] In 1824 Sadi Carnot described a thermodynamic system as the working substance (such as the volume of steam) of any heat engine under study. The very existence of such thermodynamic systems may be considered a fundamental postulate of equilibrium thermodynamics, though it is not listed as a numbered law.[10][11] According to Bailyn, the commonly rehearsed statement of the zeroth law of thermodynamics is a consequence of this fundamental postulate.[12] In equilibrium thermodynamics the state variables do not include fluxes because in a state of thermodynamic equilibrium all fluxes have zero values by definition. Equilibrium thermodynamic processes may of course involve fluxes but these must have ceased by the time a thermodynamic process or operation is complete bringing a system to its eventual thermodynamic state. Non-equilibrium thermodynamics allows its state variables to include nonzero fluxes, that describe transfers of matter or energy or entropy between a system and its surroundings.[13]

Contents [hide]

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1 Overview

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2 History

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3 Walls

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4 Surroundings

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5 Open system o

5.1 Flow process

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5.2 Selective transfer of matter

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6 Closed system

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7 Isolated system

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8 Mechanically isolated system

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9 Systems in equilibrium

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10 See also

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11 References

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12 External links

Overview[edit] Thermodynamics

The classical Carnot heat engine Branches[show] Laws[show] Systems[show] System properties[show]

Material properties[show] Equations[show] Potentials[show] 

History

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Culture [show]

Scientists[show] Book:Thermodynamics

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V

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T

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E

Thermodynamics describes the macroscopic physics of matter and energy, especially including heat transfer, by using the concept of the thermodynamic system, a region of the universe that is under study, specified by thermodynamic state variables, together with the kinds of transfer that may occur between it and its surroundings, as determined by the physical properties of the walls of the system. An example system is the system of hot liquid water and solid table salt in a sealed, insulated test tube held in a vacuum (the surroundings). The test tube constantly loses heat in the form of black-body radiation, but the heat loss progresses very slowly. If there is another process going on in the test tube, for example the dissolution of the salt crystals, it probably occurs so quickly that any heat lost to the test tube during that time can be neglected. Thermodynamics in general does not measure time, but it does sometimes accept limitations on the time frame of a process.

History[edit] The first to develop the concept of a thermodynamic system was the French physicist Sadi Carnot whose 1824 Reflections on the Motive Power of Fire studied what he called the working substance, e.g., typically a body of water vapor, in steam engines, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a heat reservoir (a boiler), a cold reservoir (a stream of cold water), or a piston (to which the working body could do work by pushing on it). In 1850, the German physicist Rudolf Clausius generalized this picture to include the concept of the surroundings, and began referring to the system as a "working body." In his 1850 manuscript On the Motive Power of Fire, Clausius wrote:

“

"With every change of volume (to the working body) a certain amo

The article Carnot heat engine shows the original piston-and-cylinder diagram used by Carnot in discussing his ideal engine; below, we see the Carnot engine as is typically modeled in current use:

Carnot engine diagram (modern) - where heat flows from a high temperature TH furnace through the fluid of the "working body" (working substance) and into the cold sink TC, thus forcing the working substance to do mechanical work W on the surroundings, via cycles of contractions and expansions.

In the diagram shown, the "working body" (system), a term introduced by Clausius in 1850, can be any fluid or vapor body through which heat Q can be introduced or transmitted through to produce work. In 1824, Sadi Carnot, in his famous paper Reflections on the Motive Power of Fire, had postulated that the fluid body could be any substance capable of expansion, such as vapor of water, vapor of alcohol, vapor of mercury, a permanent gas, or air, etc. Though, in these early years, engines came in a number of configurations, typically QH was supplied by a boiler, wherein water boiled over a furnace; QC was typically a stream of cold flowing water in the form of a condenser located on a separate part of the engine. The output work W was the movement of the piston as it turned a crank-arm, which typically turned a pulley to lift water out of flooded salt mines. Carnot defined work as "weight lifted through a height."

Walls[edit] A system is enclosed by walls that bound it and connect it to its surroundings. [14][15][16][17][18][19] Often a wall restricts passage across it by some form of matter or energy, making the connection indirect. Sometimes a wall is no more than an imaginary two-dimensional closed surface through which the connection to the surroundings is direct. Topologically, it is often considered nearly or piecewise smoothly homeomorphic with a two-sphere (ordinary sphere like a surface that forms the boundary of a ball in three dimensions), because a system is often considered simply connected.

A wall can be fixed (e.g. a constant volume reactor) or moveable (e.g. a piston). For example, in a reciprocating engine, a fixed wall means the piston is locked at its position; then, a constant volume process may occur. In that same engine, a piston may be unlocked and allowed to move in and out. Ideally, a wall may be declared adiabatic,diathermal, impermeable, permeable, or semi-permeable. Actual physical materials that provide walls with such idealized properties are not always readily available. Anything that passes across the boundary and effects a change in the contents of the system must be accounted for in an appropriate balance equation. The volume can be the region surrounding a single atom resonating energy, such as Max Planck defined in 1900; it can be a body of steam or air in a steam engine, such as Sadi Carnot defined in 1824. It could also be just one nuclide (i.e. a system of quarks) as hypothesized in quantum thermodynamics.

Surroundings[edit] See also: Environment (systems) The system is the part of the universe being studied, while the surroundings is the remainder of the universe that lies outside the boundaries of the system. It is also known as theenvironment, and the reservoir. Depending on the type of system, it may interact with the system by exchanging mass, energy (including heat and work), momentum, electric charge, or other conserved properties. The environment is ignored in analysis of the system, except in regards to these interactions.

Open system[edit]

Generic open system scheme. Exchanges of matter or energy with system's surroundings are represented by input and output flows.

In an open system, matter may flow in and out of some segments of the system boundaries. There may be other segments of the system boundaries that pass heat or work but not matter. Respective account is kept of the transfers of energy across those and any other several boundary segments.

Flow process[edit]

During steady, continuous operation, an energy balance applied to an open system equates shaft work performed by the system to heat added plus net enthalpy added.

The region of space enclosed by open system boundaries is usually called a control volume. It may or may not correspond to physical walls. It is convenient to define the shape of the control volume so that all flow of matter, in or out, occurs perpendicular to its surface. One may consider a process in which the matter flowing into and out of the system is chemically homogeneous. [20]

Then the inflowing matter performs work as if it were driving a piston of fluid into the system.

Also, the system performs work as if it were driving out a piston of fluid. Through the system walls that do not pass matter, heat (δQ) and work (δW) transfers may be defined, including shaft work. Classical thermodynamics considers processes for a system that is initially and finally in its own internal state of thermodynamic equilibrium, with no flow. This is feasible also under some restrictions, if the system is a mass of fluid flowing at a uniform rate. Then for many purposes a process, called a flow process, may be considered in accord with classical thermodynamics as if the classical rule of no flow were effective.[21] For the present introductory account, it is supposed that the kinetic energy of flow, and the potential energy of elevation in the gravity field, do not change, and that the walls, other than the matter inlet and outlet, are rigid and motionless. Under these conditions, the first law of thermodynamics for a flow process states: the increase in the internal energy of a system is equal to the amount of energy added to the system by matter flowing in and by heating, minus the amount lost by matter flowing out and in the form of work done by the system. Under these conditions, the first law for a flow process is written:

where Uin and Uout respectively denote the average internal energy entering and leaving the system with the flowing matter. There are then two types of work performed: 'flow work' described above, which is performed on the fluid in the control volume (this is also often called ' PV work'), and 'shaft work', which may be performed by the fluid in the control volume on some mechanical device with a shaft. These two types of work are expressed in the equation:

Substitution into the equation above for the control volume cv yields:

The definition of enthalpy, H = U + PV, permits us to use this thermodynamic potential to account jointly for internal energy U and PV work in fluids for a flow process:

During steady-state operation of a device (see turbine, pump, and engine), any system property within the control volume is independent of time. Therefore, the internal energy of the system enclosed by the control volume remains constant, which implies that dUcv in the expression above may be set equal to zero. This yields a useful expression for thepower generation or requirement for these devices with chemical homogeneity in the absence of chemical reactions:

This expression is described by the diagram above.

Selective transfer of matter[edit] For a thermodynamic process, the precise physical properties of the walls and surroundings of the system are important, because they determine the possible processes. An open system has one or several walls that allow transfer of matter. To account for the internal energy of the open system, this requires energy transfer terms in addition to those for heat and work. It also leads to the idea of the chemical potential. A wall selectively permeable only to a pure substance can put the system in diffusive contact with a reservoir of that pure substance in the surroundings. Then a process is possible in which that pure substance is transferred between system and surroundings. Also, across that wall a contact equilibrium with respect to that substance is possible. By suitable thermodynamic operations, the pure substance reservoir can be dealt with as a closed system. Its internal energy and its entropy can be determined as functions of its temperature, pressure, and mole number. A thermodynamic operation can render impermeable to matter all system walls other than the contact equilibrium wall for that substance. This allows the definition of an intensive state variable, with respect to a reference state of the surroundings, for that substance. The intensive variable is called the chemical potential; for component substance i it is usually denoted μi. The

corresponding extensive variable can be the number of moles Ni of the component substance in the system. For a contact equilibrium across a wall permeable to a substance, the chemical potentials of the substance must be same on either side of the wall. This is part of the nature of thermodynamic equilibrium, and may be regarded as related to the zeroth law of thermodynamics.[22]

Closed system[edit] Main article: Closed system § In thermodynamics In a closed system, no mass may be transferred in or out of the system boundaries. The system always contains the same amount of matter, but heat and work can be exchanged across the boundary of the system. Whether a system can exchange heat, work, or both is dependent on the property of its boundary. 

Adiabatic boundary – not allowing any heat exchange: A thermally isolated system



Rigid boundary – not allowing exchange of work: A mechanically isolated system

One example is fluid being compressed by a piston in a cylinder. Another example of a closed system is a bomb calorimeter, a type of constantvolume calorimeter used in measuring the heat of combustion of a particular reaction. Electrical energy travels across the boundary to produce a spark between the electrodes and initiates combustion. Heat transfer occurs across the boundary after combustion but no mass transfer takes place either way. Beginning with the first law of thermodynamics for an open system, this is expressed as:

where U is internal energy, Q is the heat added to the system, W is the work done by the system, and since no mass is transferred in or out of the system, both expressions involving mass flow are zero and the first law of thermodynamics for a closed system is derived. The first law of thermodynamics for a closed system states that the increase of internal energy of the system equals the amount of heat added to the system minus the work done by the system. For infinitesimal changes the first law for closed systems is stated by:

If the work is due to a volume expansion by dV at a pressure P than:

For a homogeneous system, in which only reversible processes can take place, the second law of thermodynamics reads:

where T is the absolute temperature and S is the entropy of the system. With these relations the fundamental thermodynamic relationship, used to compute changes in internal energy, is expressed as:

For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. However, for systems undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically:

where Nj is the number of j-type molecules, aij is the number of atoms of element i in molecule j and bi0 is the total number of atoms of element i in the system, which remains constant, since the system is closed. There is one such equation for each element in the system.

Isolated system[edit] Main article: Isolated system An isolated system is more restrictive than a closed system as it does not interact with its surroundings in any way. Mass and energy remains constant within the system, and no energy or mass transfer takes place across the boundary. As time passes in

an isolated system, internal differences in the system tend to even out and pressures and temperatures tend to equalize, as do density differences. A system in which all equalizing processes have gone practically to completion is in a state of thermodynamic equilibrium. Truly isolated physical systems do not exist in reality (except perhaps for the universe as a whole), because, for example, there is always gravity between a system with mass and masses elsewhere.[23][24][25][26][27] However, real systems may behave nearly as an isolated system for finite (possibly very long) times. The concept of an isolated system can serve as a useful model approximating many real-world situations. It is an acceptable idealization used in constructing mathematical models of certain natural phenomena. In the attempt to justify the postulate of entropy increase in the second law of thermodynamics, Boltzmann’s Htheorem used equations, which assumed that a system (for example, a gas) was isolated. That is all the mechanical degrees of freedom could be specified, treating the walls simply as mirror boundary conditions. This inevitably led toLoschmidt's paradox. However, if the stochastic behavior of the molecules in actual walls is considered, along with the randomizing effect of the ambient, background thermal radiation, Boltzmann’s assumption of molecular chaos can be justified. The second law of thermodynamics for isolated systems states that the entropy of an isolated system not in equilibrium tends to increase over time, approaching maximum value at equilibrium. Overall, in an isolated system, the internal energy is constant and the entropy can never decrease. A closed system's entropy can decrease e.g. when heat is extracted from the system.

It is important to note that isolated systems are not equivalent to closed systems. Closed systems cannot exchange matter with the surroundings, but can exchange energy. Isolated systems can exchange neither matter nor energy with their surroundings, and as such are only theoretical and do not exist in reality (except, possibly, the entire universe). It is worth noting that 'closed system' is often used in thermodynamics discussions when 'isolated system' would be correct - i.e. there is an assumption that energy does not enter or leave the system.

Mechanically isolated system[edit] Main article: Mechanically isolated system A mechanically isolated system can exchange no work energy with its environment, but may exchange heat energy and/or mass with its environment. The internal energy of a mechanically isolated system may therefore change due to the exchange of heat energy and mass. For a simple system, mechanical isolation is equivalent to constant volume and any process which occurs in such a simple system is said to be isochoric.

Systems in equilibrium[edit] At thermodynamic equilibrium, a system's properties are, by definition, unchanging in time. Systems in equilibrium are much simpler and easier to understand than systems not in equilibrium. In some cases, when analyzing a thermodynamic process, one can assume that each intermediate state in the process is at equilibrium. This considerably simplifies the analysis. In isolated systems it is consistently observed that as time goes on internal rearrangements diminish

and stable conditions are approached. Pressures and temperatures tend to equalize, and matter arranges itself into one or a few relatively homogeneous phases. A system in which all processes of change have gone practically to completion is considered in a state of thermodynamic equilibrium. The thermodynamic properties of a system in equilibrium are unchanging in time. Equilibrium system states are much easier to describe in a deterministic manner than non-equilibrium states. For a process to be reversible, each step in the process must be reversible. For a step in a process to be reversible, the system must be in equilibrium throughout the step. That ideal cannot be accomplished in practice because no step can be taken without perturbing the system from equilibrium, but the ideal can be approached by making changes slowly. Bioenergetic systems are metabolic processes which relate to the flow of energy in the living organisms. Those processes convert the energy into adenosine triphosphate, which is the form of chemical energy suitable for muscular activity. There are two main forms of synthesis of adenosine triphosphate: aerobic, which involves oxygen from the bloodstream, and anaerobic, which does not. Bioenergetics is the field of biology which studies the bioenergetic systems. Contents [hide]



1 Overview



2 Adenosine triphosphate



3 The principle of coupled reactions



4 Aerobic and anaerobic metabolism



5 ATP–CP: the phosphagen system



6 Anaerobic system



7 Aerobic system



8 How they work



9 References



10 Further reading

Overview[edit] The cellular respiration process that converts food energy into adenosine triphosphate (a form of energy) is largely dependent on the availability of oxygen. During exercise, the supply and demand of oxygen available to muscle cells is affected by the duration and intensity of the exercise and by the individual's cardiorespiratory fitness level. There are three exercise energy systems that can be selectively recruited, depending on the amount of oxygen available, as part of the cellular respiration process to generate the ATP energy for the muscles. They are adenosine triphosphate, the anaerobic system and the aerobic system.

Adenosine triphosphate[edit] Adenosine triphosphate (ATP) is the usable form of chemical energy for muscular activity. It is stored in most cells, particularly in muscle cells. Other forms of chemical energy, such as those available from food, must be transferred into ATP form before they can be utilized by the muscle cells.[1]

The principle of coupled reactions[edit] Since energy is released when ATP is broken down, energy is required to rebuild or resynthesize ATP. The building blocks of ATP synthesis are the by-products of its breakdown;adenosine diphosphate (ADP) and inorganic phosphate (Pi). The energy for ATP resynthesis comes from three different series of chemical reactions that take place within the body. Two of the three depend upon the food we eat, whereas the other depends upon a chemical compound called phosphocreatine. The energy released from any of these three series of hi reactions is coupled with the energy needs of the reaction that resynthesizes ATP. The separate reactions are functionally linked together in such a way that the energy released by the one is always used by the other.[2] There are three methods to resynthesize ATP: 

ATP–CP system (phosphogen system) – This system is used only for very short durations of up to 10 seconds. The ATP–CP system neither uses oxygen nor produceslactic acid if oxygen is unavailable and is thus said to be alactic anaerobic. This is the primary system behind very short, powerful movements like a golf swing, a 100 m sprint, or powerlifting.



Anaerobic system – Predominates in supplying energy for exercises lasting less than two minutes. Also known as the glycolytic system. An example of an activity of the intensity and duration that this system works under would be a 400 m sprint.



Aerobic system – This is the long-duration energy system. By five minutes of exercise, the O2 system is clearly the dominant system. In a 1 km run, this system is already providing approximately half the energy; in a marathon run it provides 98% or more.[3]

Aerobic and anaerobic metabolism[edit] The term metabolism refers to the various series of chemical reactions that take place within the body. Aerobic refers to the presence of oxygen, whereas anaerobic means with series of chemical reactions that does not require the presence of oxygen. The ATP-CP series and the lactic acid series are anaerobic, whereas the oxygen series, is aerobic. [4]

ATP–CP: the phosphagen system[edit]

(A) Phosphocreatine, which is stored in muscle cells, contains a high energy bond. (B) When creatine phosphate is broken down during muscular contraction, a large amount of energy is released. The energy released is coupled with the energy requirement to resynthesize ATP.

Creatine phosphate (CP), like ATP, is stored in the muscle cells. When it is broken down, a large amount of energy is released. The energy released is coupled to the energy requirement necessary for the resynthesis of ATP. The total muscular stores of both ATP and CP are very small. Thus, the amount of energy obtainable through this system is limited. If an individual were to run 100 meters as fast as they could, the phosphagen stores in the working muscles would probably be exhausted by the end of the sprint, about 15–30 seconds later. However, the usefulness of the ATP-CP system lies in the rapid availability of energy rather than quantity. This is extremely important with respect to the kinds of physical activities that humans are capable of performing.[5]

Anaerobic system[edit] This system is known as anaerobic glycolysis. “Glycolysis” refers to the breakdown of sugar. In this system, the breakdown of sugar supplies the necessary energy from which ATP is manufactured. When sugar is metabolized anaerobically, it is only partially broken down and one

of the by-products is lactic acid. This process creates enough energy to couple with the energy requirements to resynthesize ATP. When H+ ions accumulate in the muscles causing the blood pH level to reach very low levels, temporary muscular fatigue results. Another limitation of the lactic acid system that relates to its anaerobic quality is that only a few moles of ATP can be resynthesized from the breakdown of sugar as compared to the yield possible when oxygen is present. This system cannot be relied on for extended periods of time. The lactic acid system, like the ATP-CP system, is extremely important, primarily because it also provides a rapid supply of ATP energy. For example, exercises that are performed at maximum rates for between 1 and 3 minutes depend heavily upon the lactic acid system for ATP energy. In activities such as running 1500 meters or a mile, the lactic acid system is used predominately for the “kick” at the end of a race.[6]

Aerobic system[edit] 

The Krebs cycle



Oxidative phosphorylation

Glycolysis – The first stage is known as glycolysis, which produces 2 ATP molecules, 2 reduced molecules of NAD (NADH), and 2 pyruvate molecules which move on to the next stage – the Krebs cycle. Glycolysis takes place in the cytoplasm of normal body cells, or the sarcoplasm of muscle cells. The Krebs cycle – This is the second stage, and the products of this stage of the aerobic system are a net production of one ATP, one carbon dioxide molecule, three reduced NAD molecules, one reduced FAD molecule (The molecules of NAD and FAD mentioned here are electron carriers, and if they are said to be reduced, this means that they have had a H+ ion added to them). The things produced here are for each turn of the Krebs cycle. The Krebs cycle turns twice for each molecule of glucose that passes through the aerobic system – as two pyruvate molecules enter the Krebs cycle. In order for the Pyruvate molecules to enter the Krebs cycle they must be converted to Acetyl Coenzyme A. During this link reaction, for each molecule of pyruvate that gets converted to Acetyl Coenzyme A, an NAD is also reduced. This stage of the aerobic system takes place in the matrix of the cells' mitochondria. Oxidative phosphorylation – This is the last stage of the aerobic system and produces the largest yield of ATP out of all the stages – a total of 34 ATP molecules. It is called oxidative phosphorylation because oxygen is the final acceptor of the electrons and hydrogen ions that leave this stage of aerobic respiration (hence oxidative) and ADP gets phosphorylated (an extra phosphate gets added) to form ATP (hence phosphorylation). This stage of the aerobic system occurs on the cristae (infoldings on the membrane of the mitochondria). The NADH+ from glycolysis and the Krebs cycle, and the FADH+ from the Krebs

cycle pass down electron carriers which are at decreasing energy levels, in which energy is released to reform ATP. Each NADH+ that passes down this electron transport chain provides enough energy for 3 molecules of ATP, and each molecule of FADH+ provides enough energy for 2 molecules of ATP. If you do your math this means that 10 total NADH+ molecules allow the rejuvenation of 30 ATP, and 2 FADH+ molecules allow for 4 ATP molecules to be rejuvenated (The total being 34 from oxidative phosphorylation, plus the 4 from the previous 2 stages meaning a total of 38 ATP being produced during the aerobic system). The NADH+ and FADH+ get oxidized to allow the NAD and FAD to return to be used in the aerobic system again, and electrons and hydrogen ions are accepted by oxygen to produce water, a harmless by-product. Preliminary Energy Audit The Preliminary Energy Audit focuses on the major energy suppliers and demands usually accounting for approximately 70% of total energy. It is essentially a preliminary data gathering and analysis effort. It uses only available data and is completed with limited diagnostic instruments. The PEA is conducted in a very short time frame i.e. 1-3 days during which the energy auditor relies on his experience together with all the relevant written, oral visual information that can lead to a quick diagnosis of the plant energy situation. The PEA focuses on the identification of obvious sources of energy wastage's. The typical out put of a PEA is a set of recommendations and immediate low cost action that can be taken up by the department head. Detailed Energy Audit The detailed audit goes beyond quantitative estimates of costs and savings. It includes engineering recommendations and well-defined project, giving due priorities. Approximately 95% of all energy is accounted for during the detailed audit. The detailed energy audit is conducted after the preliminary energy audit. Sophisticated instrumentation including flow meter, flue gas analyzer and scanner are use of compute energy efficiency. Scope of work for detailed Energy Audit 

Review of Electricity Bills, Contract Demand and Power Factor: For the last one year, in which possibility will be explored for further reduction of contract demand and improvement of power factor



Electrical System Network : Which would include detailed study of all the Transformer operations of various Ratings / Capacities, their operational pattern, Loading, No Load Losses, Power Factor Measurement on the Main Power Distribution Boards and scope for improvement if any. The study would also cover possible improvements in energy metering systems for better control and monitoring.



Study of Motors and Pumps Loading : Study of motors (above 10 kW) in terms of measurement of voltage (V), Current (I), Power (kW) and power factor and thereby suggesting measures for energy saving like reduction in size of motors or installation of energy saving device in the existing motors. Study of Pumps and their flow, thereby suggesting measures for energy saving like reduction in size of Motors and Pumps or installation of energy saving device in the existing motors / optimization of pumps.



Study of Air conditioning plant : w.r.t measurement of Specific Energy consumption i.e kW/TR of refrigeration, study of Refrigerant Compressors, Chilling Units, etc. Further, various measures would be suggested to improve its performance.



Cooling Tower: This would include detailed study of the operational performance of the cooling towers through measurements of temperature differential, air/water flow rate, to enable evaluate specific performance parameters like approach, effectiveness

etc. 

Performance Evaluation of Boilers: This includes detailed study of boiler efficiency, Thermal insulation survey and flue gas analysis.



Performance Evaluation of Turbines: This includes detailed study of Turbine efficiency, Waste heat recovery.

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Performance Evaluation of Air Compressor: This includes detailed study of Air compressor system for finding its performance and specific energy consumption

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Evaluation of Condenser performance: This includes detailed study of condenser performance and opportunities for waste heat recovery

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Performance Evaluation of Burners / Furnace : This includes detailed study on performance of Furnace / Burner, thermal insulation survey for finding its efficiency

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Windows / Split Air Conditioners: Performance shall be evaluated as regards, their input power vis-a-vis TR capacity and performance will be compared to improve to the best in the category

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Illumination: Study of the illumination system, LUX level in various areas, area lighting etc. and suggest measures for improvements and energy conservation opportunity wherever feasible.

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DG Set: Study the operations of DG sets to evaluate their average cost of Power Generation, Specific Energy Generation and subsequently identify areas wherein energy savings could be achieved after analysing the operational practices etc. of the DG sets.

The entire recommendations would be backed up with techno-economic calculations including the estimated investments required for implementation of the suggested measures and simple payback period. Measurement would be made using appropriate in

Energy conservation'' means to reduce the quantity of energy that is used for different purposes. This practice may result in increase of financial capital, environmental value, national and personal security, and human comfort. Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote economic, political and environmental sustainability. Industrial and commercial users may want to increase efficiency and thus maximize profit. On a larger scale, energy conservation is an important element of energy policy. In general, energy conservation reduces the energy consumption and energy demand per capita. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production.

By reducing emissions, energy conservation is an important method to prevent climate change. Energy conservation makes it easier to replace non-renewable resources withrenewable energy. Energy conservation is often the most economical solution to energy shortages. Natural resource and energy conservation is achieved by managing materials more efficiently. Choose from the efforts and resources below to learn how to conserve resources at home and at work.  Reduce, Reuse, Recycle: Learn ways to reduce household and industrial waste. Three primary strategies for effectively managing materials and waste are reduce, reuse, and recycle. o Reduce waste by making smart decisions when purchasing products, including the consideration of product packaging. o Reuse containers and products. o Recycle materials ranging from paper to food scraps, yard trimmings, and electronics. o Purchase products manufactured with recycled content.

 Reducing Food Waste: Information for businesses and organizations on reducing food waste.

 Composting for Facilities: Learn more about industrial composting.

 Sustainable Materials Management (SMM): SMM is a systemic approach to using and reusing materials more productively over their entire lifecycles. Learn what EPA is doing to advance SMM and how to become involved.

 Conservation Tools: Tools and programs that promote waste reduction and recycling. Read guidelines for businesses regarding purchasing recycled materials, controlling solid waste management costs, and streamlining and improving operations. Learn about evaluating effectiveness of recycling in the community.

 Common Wastes and Materials: Common materials from the municipal, commercial, and industrial waste streams that have good opportunities for recycling and reuse.

Building Evaluation Tools VERDE. Building Evaluation Certification Method

and

Environmental

In the past few years, the concepts of “sustainable or green building” have evolved, incorporating new notions and concepts. Due to several factors like climate change or a shortage in natural resources, we are witnessing an increase in the environmental awareness of both citizens and designers. This has lead us to look

beyond traditional construction methods, taking other problems into consideration, such as energy saving or material selection, following ecological criteria. Nowadays, some ecological and energetic saving measures are generally taken by designers, depending on the context and location of the building, its characteristics and their own knowledge on the subject. Nevertheless, it is more complex to assess whether these measures imply that the building is truly innovative, eco-friendly and sustainable, making it worthy of obtaining an Environmental Certification. At any rate, it becomes clear that introducing one single element is not enough to confirm that a building is actually sustainable. Considering these arguments the Technical Committee at GBCe has put together criteria and established rules to define the requirements and limits a building must meet to be qualified as sustainable, and therefore obtain a GBC España Certificate-VERDE. The evaluation system is based on a feature evaluating method, in accordance with the CTE (Código Técnico de la Edificación, Technical Building Code) and European Guidelines. At its core are bio-architecture principles: the building’s respect for the environment, whether it is compatible with its surroundings and the high comfort and quality of life levels required for the users.

Evaluation Criteria The evaluation criteria are grouped into subjects, as follows:           

A. Site Selection, Project Planning and Development Recycling strategies for the project or community Autochthonous plants Atmospheric light pollution B. Energy and atmosphere Use of non-renewable energy resources in the manufacture of building materials Use of non-renewable energy resources to transport the building materials Reduction of operating energy Reduction of peak electric loads Provision of on-site renewable energy systems Strategies to reduce the emission of photo-oxidants and NOx substances Strategies to reduce substances aggressive to the stratospheric ozone layer, from building materials and HVAC systems

                     

C. Natural Resources Design measures to reduce use of potable water for occupancy needs Rainwater storage for later reuse Design features for a split grey/potable water system for later reuse Natural impact and hazardous waste generated by building materials used Demolition, dismantling, reusage and recycling strategies Natural impact and hazardous waste generated in the construction process D. Indoor environmental Quality Removal, before occupancy, of pollutants emitted by new interior finishing materials Indoor air CO2 concentration Air movement in mechanically ventilated occupancies Effectiveness of ventilation in naturally ventilated occupancies Air temperature and relative humidity in mechanically cooled occupancies Air temperature in naturally ventilated occupancies Day lighting in primary occupancy areas Glare in non-residential occupancies Illumination levels and quality of lighting in non-residential occupancy design Noise attenuation through the exterior envelope Transmission of facility equipment noise to primary occupancies Noise attenuation between primary occupancy areas E. Service Quality Spatial efficiency Volumetric efficiency

                   

Provision and operation of an effective facility management control system Capability for partial operation of facility technical systems Degree of local control of lighting systems in non-residential occupancies Degree of personal control of technical systems by occupants Ability to modify facility technical systems Strategies to maximize adaptability of structural type and payout for the future functional requirements Strategies to minimize constraints imposed by floor-to-floor heights on future functional requirements Strategies to minimize constraints imposed by building envelope and technical systems for future functional requirements Adaptability to future changes in type of energy supply Development and implementation of a maintenance management plan On-going monitoring and verification of building performance (energy and water) F. Social and Economic Aspects Access for physically handicapped persons Access to direct sunlight from living areas of dwelling units Access to private open space from dwelling units Visual privacy from the exterior in principal areas of dwelling units Access to outside views from work areas Minimization of construction cost Minimization of operating and maintenance cost Affordability of residential rental or cost levels IMPACTS

IMPACT

INDICATOR

Climate Change

kg CO2 eq per year

Increase in UV radiation at ground level

kg CFC11 eq year

Soil fertility loss

kg SO2 eq per year

Aquatic life loss

kg PO4 eq per year

Health and cancer risk

kg C2H4 eq year

Changes in local biodiversity

%

Exhaustion of non-reweable energy resources, primary energy

MJ

Exhaustion of non-reneweable energy resources, other than primary energy

kg material

Exhaustion of potable water

m3

Land use

m2

Soil exhaustion due to non-hazardous material disposal

m3

Hazardous waste storage or disposal

kg

Radioactive waste storage or disposal

kg

Health, well-being and productivity of users

%

Financial risk or benefit for investors – Life cycle cost

€/m2

Criteria and Impact Quantification

per

A benchmark, or reference score, is assigned to each criterion. They are set based on the revision of the laws or regulations in force, the performance analysis of the surrounding buildings. The score goes from 0 to 5, in the following order:   

0 reference value level that implies compliance with current legislation or common practice 3 value level implying good practice 5 value level implying the best possible practice with an acceptable cost The final score will be obtained by comparing and adjusting the impact reduction in relation to the reference building. The load assigned to each impact is related to the significance of such impact on a worldwide scale, at global level, and to the local environment existing situation, at regional level. At present, the assigned load for the several impact categories follows indications from the “OSE Report on Sustainability in Spain 2007” and the “MMA Report on the Environmental Profile in Spain 2007”. New Building Design & Construction: Energy-Efficient from the Start For new construction projects, EPA:  Goes beyond the applicable codes and regulations (e.g., 10 CFR Part 435 Subpart A) to pursue DOE design initiatives encouraged by the Energy Policy Act and EO 12902. Such initiatives include passive energy design strategies, use of waste energy and reclaimable resources, and the use of solar and renewable energy  Maintaines among staff, site managers, site designers and contractors a high level of awareness of technology developments, especially renewable energy technologies, and a commitment to use them whenever possible, and where cost effective  Ensures that all new environmental control systems installed are highly automated, using a comprehensive monitoring and control strategy designed to continuously monitor the system’s performance for delivery of services at the expected energy efficiency and pollution prevention levels.  The Program of Requests for new laboratories planned for Las Vegas, NV; Kansas City, KS; Edison, NJ; and Lexington, MA; are being amended to include requirements for renewable technology applications. Green Buildings Program Vast opportunities for implementing regulatory and executive order procurement requirements exist in building construction, renovation, and maintenance. For several years, EPA has been implementing Green Building strategies in a variety of ways, which are expanding with each construction and renovation project. To promote a healthful and productive working environment, the Green Buildings program incorporates principles of energy and resource efficiency, applies waste reduction and pollution prevention practices, ensures unpolluted indoor air, and uses natural light as a light and heat source whenever possible. The Green Buildings Vision and Policy statement, on page 22, serves as a guide for EPA and as a model for other agencies. It represents a holistic, systems approach to sustainable building design, renovation, and maintenance. There are many examples of Green Building practices that are incorporated in numerous solicitation for offers (SFOs) for construction and/or renovation activities at EPA facilities. For instance, SFOs have specified the collection of recyclable waste materials, the recycling of construction and renovation debris, and the reuse of existing building material. Also, SFOs specify

the use of environmentally preferable building products and materials, promote low VOC-content adhesives, and restrict the use of products made from endangered or restricted wood. Several upcoming and recent EPA facility construction projects demonstrate technologies and concepts that integrate a systems approach to Green Buildings procurement using many of the practices previously described. These facilities include the New Headquarters Buildings (Washington, DC), the New Consolidated RTP Facility (Research Triangle Park, NC), the Region IV Science and Ecosystems Support Laboratory (Athens, GA), Region IV Office (Atlanta, GA), Region III Office (Philadelphia, PA), Region VII Central Regional Laboratory (Kansas City, KS), National Vehicle and Fuel Emissions Laboratory (Ann Arbor, MI), and the Fort Meade Environmental Science Center (Fort Meade, MD). The following EPA facilities provide examples of the variety of energy conservation and pollution prevention opportunities which were addressed through the Green Buildings program. Athens, Georgia A variety of pollution prevention opportunities were considered and incorporated into the design and construction of the new Region IV laboratory in Athens, Georgia. In incorporating Green Building concepts, OA was able to minimize off-gas environmental contaminants in materials and GREEN BUILDINGS VISION AND POLICY STATEMENT In order to maintain leadership in environmental protection, EPA must lead by example. Through sustainable design and construction of EPA facilities we will model responsible environmental behavior and help create the framework within which the building industry as a whole can shift towards practices which will promote "Green Buildings". Green Buildings are structures that incorporate the principles of sustainable design -- design in which the impact of a building on the environment will be minimal over the lifetime of that building. Green Buildings incorporate principles of energy and resource efficiency, practical applications of waste reduction and pollution prevention, good indoor air quality and natural light to promote occupant health and productivity, and transportation efficiency in design and construction, during use and reuse. Agency facilities, both new and existing, should serve as models for a healthy workplace with minimal environmental impacts. To achieve this goal, EPA will utilize both innovative, state-of-theart technologies and a holistic approach to design, construction, renovation, and use. EPA will work with the private sector to identify opportunities for innovation and help create markets for both products and design concepts. Important considerations in the design, construction and use of EPA-owned and -leased facilities include the following:  Site planning that utilizes resources naturally occurring on the site such as solar and wind energy, natural shading, native plant materials, topography and drainage  Location and programs to optimize use of existing infrastructure and transportation options, including the use of alternative work modes such as telecommuting and teleconferencing  Use of recycled content and environmentally preferable construction materials and furnishings, consistent with EPA Procurement Guidelines

 Minimization of energy and materials waste throughout the buildings life cycle, from design through demolition or reuse  Design of the building envelope for energy efficiency  Use of materials and design strategies to achieve optimal indoor environmental quality, particularly including light and air, to maximize health and productivity  Operation systems and practices which support an integrated waste management system  Recycling of building materials at demolition  Management of water as a limited resource in site design, building construction and building operations  Utilization of solar and other renewable technologies, where appropriate Evaluation of trade-offs will be an important component of the design of Green Buildings. Where the goals of a Green Building are contradictory (for example, increased ventilation vs. increased energy efficiency), the trade-offs will have to be evaluated in a holistic framework to achieve longterm benefits for the environment. Also, the physical considerations must be balanced with other policy objectives such as environmental justice, particularly with regards to site location. We anticipate that there may not be always be single answers to recurring building issues, but we will adopt a consistent approach to evaluating all buildings for sustainable design considerations. products (e.g., adhesives, varnishes, carpets, paints), use CFC-free insulations and refrigerants, and avoid materials in limited supply or not from sustainable sources. OA was able to use recycled content products (e.g., insulation, wall board, and fly-ash concrete), maximize shading through liberal use of trees and shrubs, and include centralized recycling stations. A variety of conservation opportunities were implemented, such as improved efficiency of refrigeration equipment, a VAV HVAC system, split-task ambient lighting system, low-flow plumbing fixtures, and trickle irrigation systems for exterior landscaping. New EPA Headquarters, Washington, DC EPA has completed construction of a consolidated headquarters facility in downtown Washington, DC. The Agency occupies a portion of the Ronald Reagan Federal Building and the adjacent Customs/Connecting Wing/Interstate Commerce Commission and Ariel Rios Buildings. EPA’s new Headquarters operates with many energy-saving features, described below. The variety of solutions implemented by EPA highlights the dynamic diversity of available responses to energy conservation needs. HVAC System  EPA required that perimeter walls be adequately insulated and all windows be recaulked and reglazed to virtually "seal" the building and reduce demand on the HVAC system by preventing the loss of cool air during the cooling season and warm air during the heating season.  Space-adjustable thermostats control VAV fans to automatically adjust the amount and temperature of the air to meet the requirements of the office or space.

 Upgraded HVAC system eliminates use of CFCs and is designed to maximize energy efficiency. Lighting  Occupancy sensors have been installed in workstations to turn off task and under-cabinet lights when the space is unoccupied for 15 minutes.  Daylighting controls and floor-wide occupancy sensors turn off lights when they are not needed.  Where possible, partitions have been kept away from external windows to allow penetration of daylight into work spaces.  Lighting system is up to 90 percent efficient; EPA expects upgrades will provide savings upwards of 40 percent over typical commercial systems.  Work space colors and lighting fixtures are designed to reduce glare. Fort Meade Environmental Science Center, MD Environmentally sound materials and processes will be incorporated into the various phases of design at the new facility in Fort Meade, MD. For example, materials for the interior finishes will be selected to minimize chemical off-gasing. Lighter colored finishes will be used in order to maximize the lighting reflectivity. In addition, no mercury, asbestos, or halon will be used within the facility, and no lead is to be used in the water piping connections. Examples of Green Building practices incorporated into the site design phase include stipulating that existing trees will be transported on-site where possible and that, to reduce the need for fertilization, new planting will include native species and grasses. Also, the existing tree stands will be preserved to the extent possible. Another example in this area is the use of recycled asphalt for wearing surfaces for parking and roadway areas. The architectural/structural design phase also provides for many practices that use environmentally benign materials and practices. For example, it is specified that building materials should include recyclable materials where possible, such as within the facility’s insulation and in concrete. In addition, wall bases and selected flooring areas will contain rubber with reclaimed material. Carpet and ceiling tile that are to be used within the facility have been specified to allow these materials to be recycled in the future. Also, a recycling center will be provided for waste materials. Research Triangle Park (RTP), NC The new 635,000 square-foot consolidated campus at RTP will house about 2,000 EPA staff and contractors in the Agency’s largest laboratory and office complex. Energy efficiency has been stressed in every aspect of the design of this new facility, which is now under design and set for completion by early 2001. For example, an integrated systems approach has maximized daylighting while keeping heat gain to a minimum. Although the orientation of the building along the steep slope of the site yields a large amount of southwestern exposure, large forests of tall pines and hardwoods have been carefully preserved to provide the building with much-needed shading. Light-colored pre-cast concrete and roofing material will help reflect radiant heat, and the articulation of the building facade will help to shade the windows from excessive mid-day sun. Insulated, low-E glass will further deflect heat gain while maximizing the daylight benefit of the abundant windows. Motion sensors and daylight dimmers will be combined with high-efficiency electronic fluorescent fixtures which comply with EPA’s Green Lights program.

Variable speed drives and high-efficiency motors and pumps are used extensively throughout the facility. VAV units and outside air economizers in the office wings keep the energy demand to a minimum. A direct digital control building automation system will tie all heating, cooling and lighting into an integrated system which will minimize energy use throughout the complex. Since laboratories are particularly energy-intensive, special care was given to the custom-designed chemical fume hoods. Each hood will have a specially designed sash which will cut the air demand by 20% in full operation. When the hood is lowered and the researcher turns off the light as he or she leaves the laboratory, air flow is cut dramatically—yielding a 70% total reduction from the energy demand of a standard fume hood. This energy savings will be realized with no compromise in worker safety protections.

MINIMIZATION OF PETROLEUM USE Refer to Appendix C for information on EPA’s vehicle fuel consumption.

CONCLUSION EPA has taken many positive steps to conserve energy over the last year. Since EPA met its 10 percent energy reduction goal in 1995, the Agency has moved beyond the traditional conservation approaches of lighting retrofits and building upgrades to a more aggressive, all-encompassing program. EPA’s partnerships with other government agencies and the private sector, use of innovative technologies and designs, and incorporation of pollution prevention programs into daily activities—as well as continuing to use the tools that helped the Agency reach past goals and milestones—is already proving useful in pursuing the 20 percent and 30 percent reduction goals. The Agency’s mission to protect the environment make meeting the 2000 and 2005 goals natural commitments, and EPA intends to turn these commitments into success stories.

Advanced building techniques A building professional's guide to more than 90 environmentally-appropriate technologies and practices. Architects, engineers and buildings managers can improve the energy and resource efficiency of commercial, industrial and multi-unit residential buildings through the use of the technologies and practices described in this web site. The following design and construction issues are covered:

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indoor air quality

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electricity production

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daylighting

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water conservation

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non-toxic materials

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energy efficiency

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waste management

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recycled materials

This web site is offered as an assistance to building designers and the inclusion of a technology does not indicate its endorsement by the sponsors. New technologies are added to the site during our updating process. If you would like to submit a technology description, please contact us.

What is a Smart Building? RESOURCES:

What is a Smart Building?

Olympic Peninsula Project (PNNL-Gridwise)

Europe's Electricity Networks of the Future (European Commission)

Smart Grid Interoperability Standards Roadmap (NIST)

Smart 2020 (Climate Group)

The first buildings ever constructed were primitive shelters made from stones, sticks, animal skins and other natural materials. While they hardly resembled the steel and glass that make up a modern city skyline, these early structures had the same purpose - to provide a comfortable space for the people inside. Buildings today are complex concatenations of structures, systems and technology. Over time, each of the components inside a building has been developed and improved, allowing modern-day building owners to select lighting, security, heating, ventilation and air conditioning systems independently, as if they were putting together a home entertainment system. But building owners today are beginning to look outside the four walls and consider the impact of their building on the electrical grid, the mission of their organization, and the global environment. To meet these objectives, it is not enough for a building to simply contain the systems that provide comfort, light and safety. Buildings of the future must connect the various pieces in an integrated, dynamic and functional way. This vision is a building that seamlessly fulfills its mission while minimizing energy cost, supporting a robust electric grid and mitigating environmental impact. At the most fundamental level, smart buildings deliver useful building services that make occupants productive (e.g. illumination, thermal comfort, air quality, physical security, sanitation, and many more) at the lowest cost and environmental impact over the building lifecycle. Reaching this vision requires adding intelligence from the beginning of design phase through to the end of the building's useful life. Smart buildings use information technology during operation to connect a variety of subsystems, which typically operate independently, so that these systems can share information to optimize total building performance. Smart buildings look beyond the building equipment within their four walls. They are connected and responsive to the smart power grid, and they interact with building operators and occupants to empower them with new levels of visibility and actionable information. Enabled by technology, this smart building connects the structure itself to the functions it exists to fulfill: 

Connecting building systems

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Connecting people and technology

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Connecting to the bottom line

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Connecting to the global environment

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Connecting to the smart power grid

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Connecting to an intelligent future

Connecting Building Systems Modern buildings contain complex mechanical devices, sophisticated control systems and a suite of features to improve the safety, comfort and productivity of occupants. Many of these systems involve machine-to-machine communication, but because the data is general in nature and the communication protocols have been proprietary, information only flows along certain paths. The smart building will require connectivity between all the equipment and systems in a building. An example is chiller plant optimization, which boosts the efficiency of chiller operation by incorporating outside weather data and information about occupancy. Another example is using data from the building security system to turn off lights and reduce cooling when occupants are not present. The movement toward interoperable, connected devices and systems within a building requires cooperation

between many different parties, many of whom are historical business competitors. Despite the challenge, voluntary collaboration over the past two decades has led to the adoption of open standards such as BACnet®, Modbus®, and LonWorks®1, leveling the playing field by enabling every manufacturer and contractor to make their contribution to a functional whole. The result is a building where lighting, air conditioning, security and other systems pass data freely back and forth – leading to higher efficiency, more safety and comfort, and lower cost operation of the facility.

Connecting People and Technology The most sophisticated software and elaborate hardware in the world would be nothing but wires and transistors without the people that use them to work more effectively. In that sense, the people that run a smart building are a crucial component of its intelligence. With budgets tight and staff constrained, there is no room for difficult training and steep learning curves in modern day facility management. Instead, a truly smart building provides intuitive tools that are designed to improve and enhance the existing efforts of the people on the ground. As the smart building evolves, the sharing of information between smart building systems and components will provide the platform for innovation. Future applications will appear as facility managers interact with tools and technology to do their jobs better – providing more comfort, more safety, and more security with less money, less energy, and less environmental impact.

Connecting to the Bottom Line A smart building can be considered a “supersystem” of interconnected building subsystems; it has been compared to the internet, which connects computer networks into one larger “supernetwork.” In a smart building, the integration of systems can be used to reduce operating costs. There are numerous ways that a smart building can save money; most involve optimized operation and increased efficiency: 

Optimized cooling and ventilation equipment – Modeling loads dynamically allows the system to spend the minimum amount of money to provide the comfort level desired.

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Matching occupancy patterns to energy use – A smart building will run leaner (and save money) when there are less people inside.

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Proactive maintenance of equipment – Analysis algorithms will detect problems in performance before they cause expensive outages, maintaining optimum efficiency along the way.

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Dynamic power consumption – By taking signals from the electricity market and altering usage in response, a smart building ensures the lowest possible energy costs and often generates revenue by selling load reductions back to the grid.

The open access to information is a platform on which significant value can be built. A smart building creates this platform by connecting information in an open format, allowing for the development of new applications that save time, energy, and operating costs, in the same way that new web applications are developed for the open information found on the internet.

Connecting to the Global Environment For decades, building management systems have automated the process of providing just enough energy to heat and cool buildings to meet comfort standards. These energy efficiency measures contribute to an organization’s sustainability goals, such as tracking and reducing greenhouse gas emissions. But if the data is trapped within the building management system, executive-level decision-makers cannot measure and act on it. Translation software called “middleware” gathers data from all automated systems throughout an enterprise – regardless of manufacturer or communications protocol – and merges it into a common platform for analytics and reporting. One result is the emergence of web-based dashboard displays that offer a visual snapshot of which facilities are experiencing high energy usage, abnormal maintenance costs, and many other situations that deserve prompt attention. This provides executives in charge of sustainability and carbon footprint management with the visibility to see the big picture of their organization, no matter how many buildings or geographic locations are involved. When information is available quickly and can be accessed anywhere, managers are able to make better decisions that

have an immediate impact on profitability.

Connecting to the Smart Power Grid Truly smart buildings will leverage knowledge that resides outside its walls and windows. The smart grid is an ideal place to start. Electricity markets are evolving toward “real time,” meaning that buildings can receive requests to reduce demand when wholesale prices are high or when grid reliability is jeopardized. In addition, dynamic electric rates are a growing trend, meaning a building is charged closer to the actual cost of producing electricity at the instant it is used instead of the average cost over long time periods. For instance, a utility on the smart grid may be programmed to read the weather forecast, and anticipate a temperature increase that will result in increased demand the following afternoon. The utility could communicate an “offer” to pay the smart building $0.50 for every kilowatt-hour drop from its average electricity usage. A smart building could accept this offer by activating an internal demand-reduction mode and thereby reducing its load. While energy use and occupant comfort are crucial to any organization and therefore require human involvement in the decision-making, technology will be the key enabler, providing building operators with the tools and information they need to make smart choices. (Facility managers are constrained as it is; there would be very limited response to participating in a smart grid if it required operators to perform a “second job” monitoring markets and reacting to signals.)

Connecting to an Intelligent Future

Smart buildings go far beyond saving energy and contributing to sustainability goals. They extend capital equipment life and also impact the security and safety of all resources – both human and capital. They enable innovation by creating a platform for accessible information. They turn buildings into virtual power generators by allowing operators to shed electric load and sell the “negawatts” into the market. They are a key component of a future where information technology and human ingenuity combine to produce the robust, low-carbon economy envisioned for the future. The advantages extend well beyond the four physical walls of the smart building. The electric grid becomes more robust and reliable. Society’s carbon footprint is minimized as renewable energy sources provide the power, balanced with a network of information that matches demand with variable supply on a minute-by-minute basis. Electric cars move people to homes and workplaces, serving as moving batteries in a smart system. And businesses operate at a new level of efficiency by using data in new ways, leveraging the connection between systems that until now have been entirely independent. These benefits are not temporary, but extend throughout the entire lifetime of the building, from modeling and design to renovation and beyond. The smart building is at the center of this vision, providing not just the roof overhead, but also the information infrastructure to make possible a truly intelligent world.

Active solar heating systems use solar energy to heat a fluid -- either liquid or air -- and then transfer the solar heat directly to the interior space or to a storage system for later use. If the solar system cannot provide adequate space heating, an auxiliary or back-up system provides the additional heat. Liquid systems are more often used when storage is included, and are well suited for radiant heating systems, boilers with hot water radiators, and even absorption heat pumps and coolers. Both liquid and air systems can supplement forced air systems.

LIQUID-BASED ACTIVE SOLAR HEATING Solar liquid collectors are most appropriate for central heating. They are the same as those used in solar domestic water heating systems. Flat-plate collectors are the most common, but evacuated tube and concentrating collectors are also available. In the collector, a heat transfer or "working" fluid such as water, antifreeze (usually non-toxic propylene glycol), or other type of liquid absorbs the solar heat. At the appropriate time, a controller operates a circulating pump to move the fluid through the collector. The liquid flows rapidly, so its temperature only increases 10° to 20°F (5.6° to 11°C ) as it moves through the collector. Heating a smaller volume of liquid to a higher temperature increases heat loss from the collector and decreases the efficiency of the system. The liquid flows to either a storage tank or a heat exchanger for immediate use. Other system components include piping, pumps, valves, an expansion tank, a heat exchanger, a storage tank, and controls. The flow rate depends on the heat transfer fluid. To learn more about types of liquid solar collectors, their sizing, maintenance, and other issues, see solar water heating.

STORING HEAT IN LIQUID SYSTEMS Liquid systems store solar heat in tanks of water or in the masonry mass of a radiant slab system. In tank type storage systems, heat from the working fluid transfers to a distribution fluid in a heat exchanger exterior to or within the tank.

Tanks are pressurized or unpressurized, depending on overall system design. Before choosing a storage tank, consider cost, size, durability, where to place it (in the basement or outside), and how to install it. You may need to construct a tank on-site if a tank of the necessary size will not fit through existing doorways. Tanks also have limits for temperature and pressure, and must meet local building, plumbing, and mechanical codes. You should also note how much insulation is necessary to prevent excessive heat loss, and what kind of protective coating or sealing is necessary to avoid corrosion or leaks. Specialty or custom tanks may be necessary in systems with very large storage requirements. They are usually stainless steel, fiberglass, or high temperature plastic. Concrete and wood (hot tub) tanks are also options. Each type of tank has its advantages and disadvantages, and all types require careful placement because of their size and weight. It may be more practical to use several smaller tanks rather than one large one. The simplest storage system option is to use standard domestic water heaters. They meet building codes for pressure vessel requirements, are lined to inhibit corrosion, and are easy to install.

DISTRIBUTING HEAT FOR LIQUID SYSTEMS You can use a radiant floor, hot water baseboards or radiators, or a central forced-air system to distribute the solar heat. In a radiant floor system, solar-heated liquid circulates through pipes embedded in a thin concrete slab floor, which then radiates heat to the room. Radiant floor heating is ideal for liquid solar systems because it performs well at relatively low temperatures. A carefully designed system may not need a separate heat storage tank, although most systems include them for temperature control. A conventional boiler or even a standard domestic water heater can supply backup heat. The slab is typically finished with tile. Radiant slab systems take longer to heat the home from a "cold start" than other types of heat distribution systems. Once they are operating, however, they provide a consistent level of heat. Carpeting and rugs will reduce the system's effectiveness. See radiant heating for more information. Hot-water baseboards and radiators require water between 160° and 180°F (71° and 82°C) to effectively heat a room. Generally, flat-plate liquid collectors heat the transfer and distribution fluids to between 90° and 120°F (32° and 49°C). Therefore, using baseboards or radiators with a solar heating system requires that the surface area of the baseboard or radiators be larger, temperature of the solar-heated liquid be increased by the backup system, or a medium-temperature solar collector (such as an evacuated tube collector) be substituted for a flat-plate collector. There are several options for incorporating a liquid system into a forced-air heating system. The basic design is to place a liquid-to-air heat exchanger, or heating coil, in the main room-air return duct before it reaches the furnace. Air returning from the living space is heated as it passes over the solar heated liquid in the heat exchanger. Additional heat is supplied as necessary by the furnace. The coil must be large enough to transfer sufficient heat to the air at the lowest operating temperature of the collector.

VENTILATION PREHEATING Solar air heating systems use air as the working fluid for absorbing and transferring solar energy. Solar air collectors can directly heat individual rooms or can potentially pre-heat the air passing into a heat recovery ventilator or through the air coil of an air-source heat pump. Air collectors produce heat earlier and later in the day than liquid systems, so they may produce more usable energy over a heating season than a liquid system of the same size. Also, unlike liquid systems, air systems do not freeze, and minor leaks in the collector or distribution ducts will not cause significant problems, although they will degrade performance. However, air is a less efficient heat transfer medium than liquid, so solar air collectors operate at lower efficiencies than solar liquid collectors. Although some early systems passed solar-heated air through a bed of rocks as energy storage, this approach is not recommended because of the inefficiencies involved, the potential problems with condensation and mold in the rock bed, and the effects of that moisture and mold on indoor air quality. Solar air collectors are often integrated into walls or roofs to hide their appearance. For instance, a tile roof could have air flow paths built into it to make use of the heat absorbed by the tiles. Most solar air heating systems are room air heaters, but relatively new devices called transpired air collectors have limited applications in homes.

ROOM AIR HEATERS Air collectors can be installed on a roof or an exterior (south-facing) wall for heating one or more rooms. Although factory-built collectors for on-site installation are available, do-it-yourselfers may choose to build and install their own air collector. A simple window air heater collector can be made for a few hundred dollars. The collector has an airtight and insulated metal frame and a black metal plate for absorbing heat with glazing in front of it. Solar radiation heats the plate that, in turn, heats the air in the collector. An electric fan or blower pulls air from the room through the collector, and blows it back into the room. Roof-mounted collectors require ducts to carry air between the room and the collector. Wall-mounted collectors are placed directly on a south-facing wall, and holes are cut through the wall for the collector air inlet and outlets. Simple "window box collectors" fit in an existing window opening. They can be active (using a fan) or passive. In passive types, air enters the bottom of the collector, rises as it is heated, and enters the room. A baffle or damper keeps the room air from flowing back into the panel (reverse thermosiphoning) when the sun is not shining. These systems only provide a small amount of heat, because the collector area is relatively small.

TRANSPIRED AIR COLLECTORS Transpired air collectors use a simple technology to capture the sun's heat to warm buildings. The collectors consist of dark, perforated metal plates installed over a building's south-facing wall. An air

space is created between the old wall and the new facade. The dark outer facade absorbs solar energy and rapidly heats up on sunny days—even when the outside air is cold. A fan or blower draws ventilation air into the building through tiny holes in the collectors and up through the air space between the collectors and the south wall. The solar energy absorbed by the collectors warms the air flowing through them by as much as 40°F. Unlike other space heating technologies, transpired air collectors require no expensive glazing. Transpired air collectors are most suitable for large buildings with high ventilation loads, a fact which makes them generally unsuitable for today's tightly sealed homes. However, small transpired air collectors could be used to pre-heat the air passing into a heat recovery ventilator or could warm the air coil on an air source heat pump, improving its efficiency and comfort level on cold days. No information is currently available on the cost effectiveness of using a transpired air collector in this way, however.

ECONOMICS AND OTHER BENEFITS OF ACTIVE SOLAR HEATING SYSTEMS Active solar heating systems are most cost-effective in cold climates with good solar resources when they are displacing the more expensive heating fuels, such as electricity, propane, and oil. Some states offer sales tax exemptions, income tax credits or deductions, and property tax exemptions or deductions for solar energy systems. The cost of an active solar heating system will vary. Commercially available collectors come with warranties of 10 years or more, and should easily last decades longer. The economics of an active space heating system improve if it also heats domestic water, because an otherwise idle collector can heat water in the summer. Heating your home with an active solar energy system can significantly reduce your fuel bills in the winter. A solar heating system will also reduce the amount of air pollution and greenhouse gases that result from your use of fossil fuels for heating or generating the electricity.

SELECTING AND SIZING A SOLAR HEATING SYSTEM Selecting the appropriate solar energy system depends on factors such as the site, design, and heating needs of your house. Local covenants may restrict your options; for example homeowner associations may not allow you to install solar collectors on certain parts of your house (although many homeowners have been successful in challenging such covenants). The local climate, the type and efficiency of the collector(s), and the collector area determine how much heat a solar heating system can provide. It is usually most economical to design an active system to provide 40% to 80% of the home's heating needs. Systems providing less than 40% of a home’s heat are rarely cost-effective except when using solar air heater collectors that heat one or two rooms and require no heat storage. A well-designed and insulated home that incorporates passive solar heating techniques will require a smaller and less costly heating system of any type, and may need very little supplemental heat other than solar.

Besides the fact that designing an active system to supply enough heat 100% of the time is generally not practical or cost-effective, most building codes and mortgage lenders require a back-up heating system. Supplementary or back-up systems supply heat when the solar system cannot meet heating requirements. Backups can range from a wood stove to a conventional central heating system.

CONTROLS FOR SOLAR HEATING SYSTEMS Controls for solar heating systems are usually more complex than those of a conventional heating system, because they have to analyze more signals and control more devices (including the conventional back-up heating system). Solar controls use sensors, switches, and/or motors to operate the system. The system uses other controls to prevent freezing or extremely high temperatures in the collectors. The heart of the control system is a differential thermostat, which measures the difference in temperature between the collectors and storage unit. When the collectors are 10° to 20°F (5.6° to 11°C) warmer than the storage unit, the thermostat turns on a pump or fan to circulate water or air through the collector to heat the storage medium or the house. The operation, performance, and cost of these controls vary. Some control systems monitor the temperature in different parts of the system to help determine how it is operating. The most sophisticated systems use microprocessors to control and optimize heat transfer and delivery to storage and zones of the house. It is possible to use a solar panel to power low voltage, direct current (DC) blowers (for air collectors) or pumps (for liquid collectors). The output of the solar panels matches available solar heat gain to the solar collector. With careful sizing, the blower or pump speed is optimized for efficient solar gain to the working fluid. During low sun conditions the blower or pump speed is slow, and during high solar gain, it runs faster. When used with a room air collector, separate controls may not be necessary. This also ensures that the system will operate in the event of utility power outage. A solar power system with battery storage can also provide power to operate a central heating system, though this is expensive for large systems.

BUILDING CODES, COVENANTS, AND REGULATIONS FOR SOLAR HEATING SYSTEMS Before installing a solar energy system, you should investigate local building codes, zoning ordinances, and subdivision covenants, as well as any special regulations pertaining to the site. You will probably need a building permit to install a solar energy system on an existing building. Not every community or municipality initially welcomes residential renewable energy installations. Although this is often due to ignorance or the comparative novelty of renewable energy systems, you must comply with existing building and permit procedures to install your system.

The matter of building code and zoning compliance for a solar system installation is typically a local issue. Even if a statewide building code is in effect, your city, county, or parish usually enforces it. Common problems homeowners have encountered with building codes include the following:    

Exceeding roof load Unacceptable heat exchangers Improper wiring Unlawful tampering with potable water supplies.

Potential zoning issues include these:   

Obstructing side yards Erecting unlawful protrusions on roofs Siting the system too close to streets or lot boundaries.

Special area regulations—such as local community, subdivision, or homeowner's association covenants—also require compliance. These covenants, historic district regulations, and flood-plain provisions can easily be overlooked. To find out what's needed for local compliance, contact your local jurisdiction's zoning and building enforcement divisions and any appropriate homeowner, subdivision, neighborhood, and/or community association(s).

INSTALLING AND MAINTAINING YOUR SOLAR HEATING SYSTEM How well an active solar energy system performs depends on effective siting, system design, and installation as well as the quality and durability of the components. Today’s collectors and controls are high quality, but it can still be a challenge finding an experienced contractor who can properly design and install the system. Once a system is in place, it has to be properly maintained to optimize its performance and avoid breakdowns. Different systems require different types of maintenance, and you should set up a calendar listing the maintenance tasks that the component manufacturers and installer recommends for your installation. Most solar water heaters are automatically covered under your homeowner's insurance policy. However, damage from freezing is generally not. Contact your insurance provider to find out what its policy is. Even if your provider will cover your system, it is best to inform them in writing that you own a new system.

Passive solar building design From Wikipedia, the free encyclopedia

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In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.[1] The key to design a passive solar building is to best take advantage of the local climate performing an accurate site analysis. Elements to be considered include window placement and size, and glazing type, thermal insulation, thermal mass, and shading.[2] Passive

solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or "retrofitted". Contents [hide]



1 Passive energy gain

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2 As a science



3 The solar path in passive design

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4 Passive solar thermodynamic principles o

4.1 Convective heat transfer

o

4.2 Radiative heat transfer

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5 Site specific considerations during design

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6 Design elements for residential buildings in temperate climates

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7 Efficiency and economics of passive solar heating

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8 Key passive solar building design concepts

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o

8.1 Direct solar gain

o

8.2 Indirect solar gain

o

8.3 Isolated solar gain

o

8.4 Heat storage

o

8.5 Insulation

o

8.6 Special glazing systems and window coverings

o

8.7 Glazing selection 

8.7.1 Equator-facing glass



8.7.2 Roof-angle glass / Skylights

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8.7.3 Angle of incident radiation

o

8.8 Operable shading and insulation devices

o

8.9 Exterior colors reflecting - absorbing 9 Landscaping and gardens

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10 Other passive solar principles o

10.1 Passive solar lighting

o

10.2 Passive solar water heating

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11 Comparison to the Passive House standard in Europe

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12 Design tools

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13 Levels of application

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14 See also

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15 References

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16 External links

Passive energy gain[edit]

Elements of passive solar design, shown in a direct gain application

Passive solar technologies use sunlight without active mechanical systems (as contrasted to active solar). Such technologies convert sunlight into usable heat (in water, air, and thermal mass), cause air-movement for ventilating, or future use, with little use of other energy sources. A common example is a solarium on the equator-side of a building.Passive cooling is the use of the same design principles to reduce summer cooling requirements. Some passive systems use a small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, and use, and reduce undesirable heat transfer. Passive solar technologies include direct and indirect solar gain for space heating, solar water heating systems based on the thermosiphon, use of thermal mass and phase-change materials for slowing indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering. More widely, passive solar technologies include the solar furnace and solar forge, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for widespread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive use of solar energy.

As a science[edit] The scientific basis for passive solar building design has been developed from a combination of climatology, thermodynamics ( particularly heat transfer: conduction (heat),convection, and electromagnetic radiation ), fluid mechanics / natural convection (passive movement of air and water without the use of electricity, fans or pumps), and humanthermal comfort based on heat index, psychrometrics and enthalpy control for buildings to be inhabited by humans or animals, sunrooms, solariums, and greenhouses for raising plants. Specific attention is divided into: the site, location and solar orientation of the building, local sun path, the prevailing level of insolation ( latitude / sunshine / clouds / precipitation (meteorology) ), design and construction quality / materials, placement / size / type of windows and walls, and incorporation of solar-energy-storing thermal mass with heat capacity. While these considerations may be directed toward any building, achieving an ideal optimized cost / performance solution requires careful, holistic, system integration engineeringof these scientific principles. Modern refinements through computer modeling (such as the comprehensive U.S. Department of Energy "Energy Plus" [3] building energy simulationsoftware), and application of decades of lessons learned (since the 1970s energy crisis) can achieve significant energy savings and reduction of environmental damage, without sacrificing functionality or aesthetics.[4] In fact, passive-solar design features such as a greenhouse / sunroom / solarium can greatly enhance the livability, daylight, views, and value of a home, at a low cost per unit of space. Much has been learned about passive solar building design since the 1970s energy crisis. Many unscientific, intuition-based expensive construction experiments have attempted and failed to achieve zero energy - the total elimination of heating-and-cooling energy bills. Passive solar building construction may not be difficult or expensive (using off-the-shelf existing materials and technology), but the scientific passive solar building design is a non-trivial engineering effort that requires significant study of previous counter-intuitive lessons learned, and time to enter, evaluate, and iteratively refine the simulation input and output. One of the most useful post-construction evaluation tools has been the use of thermography using digital thermal imaging cameras for a formal quantitative scientific energy audit. Thermal imaging can be used to document areas of poor thermal performance such as the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day. The scientific lessons learned over the last three decades have been captured in sophisticated comprehensive building energy simulation computer software systems (like U.S. DOE Energy Plus, et al.). Scientific passive solar building design with quantitative cost benefit product optimization is not easy for a novice. The level of complexity has resulted in ongoing bad-architecture, and many intuition-based, unscientific construction experiments that disappoint their designers and waste a significant portion of their construction budget on inappropriate ideas. The economic motivation for scientific design and engineering is significant. If it had been applied comprehensively to new building construction beginning in 1980 (based on 1970's lessons learned), America could be saving over $250,000,000 per year on expensive energy and related pollution today.[citation needed] Since 1979, Passive Solar Building Design has been a critical element of achieving zero energy by educational institution experiments, and governments around the world, including the U.S. Department of Energy, and the energy research scientists that they have supported for decades. The cost effective proof of concept was established decades ago, but cultural assimilation into architecture, construction trades, and building-owner decision making has been very slow and difficult to change.[citation needed]

The new terms "Architectural Science" and "Architectural Technology" are being added to some schools of Architecture, with a future goal of teaching the above scientific and energyengineering principles.[citation needed]

The solar path in passive design[edit]

Solar altitude over a year; latitude based on New York, New York

Main articles: Sun path and Position of the Sun The ability to achieve these goals simultaneously is fundamentally dependent on the seasonal variations in the sun's path throughout the day. This occurs as a result of the inclination of the Earth's axis of rotation in relation to its orbit. The sun path is unique for any given latitude. In Northern Hemisphere non-tropical latitudes farther than 23.5 degrees from the equator: 

The sun will reach its highest point toward the south (in the direction of the equator)



As winter solstice approaches, the angle at which the sun rises and sets progressively moves further toward the South and the daylight hours will become shorter



The opposite is noted in summer where the sun will rise and set further toward the North and the daylight hours will lengthen[5]

The converse is observed in the Southern Hemisphere, but the sun rises to the east and sets toward the west regardless of which hemisphere you are in. In equatorial regions at less than 23.5 degrees, the position of the sun at solar noon will oscillate from north to south and back again during the year.[6] In regions closer than 23.5 degrees from either north-or-south pole, during summer the sun will trace a complete circle in the sky without setting whilst it will never appear above the horizon six months later, during the height of winter.[7] The 47-degree difference in the altitude of the sun at solar noon between winter and summer forms the basis of passive solar design. This information is combined with local climatic data (degree day) heating and cooling requirements to determine at what time of the year solar gain will be beneficial for thermal comfort, and when it should be blocked with shading. By strategic placement of items such as glazing and shading devices, the percent of solar gain entering a building can be controlled throughout the year. One passive solar sun path design problem is that although the sun is in the same relative position six weeks before, and six weeks after, the solstice, due to "thermal lag" from the thermal mass of the Earth, the temperature and solar gain requirements are quite different before and

after the summer or winter solstice. Movable shutters, shades, shade screens, or window quilts can accommodate day-to-day and hour-to-hour solar gain and insulation requirements. Careful arrangement of rooms completes the passive solar design. A common recommendation for residential dwellings is to place living areas facing solar noon and sleeping quarters on the opposite side.[8] A heliodon is a traditional movable light device used by architects and designers to help model sun path effects. In modern times, 3D computer graphics can visually simulate this data, and calculate performance predictions.[4]

Passive solar thermodynamic principles[edit] Personal thermal comfort is a function of personal health factors (medical, psychological, sociological and situational), ambient air temperature, mean radiant temperature, air movement (wind chill, turbulence) and relative humidity (affecting human evaporative cooling). Heat transfer in buildings occurs through convection, conduction, and thermal radiation through roof, walls, floor and windows.[9]

Convective heat transfer[edit] Convective heat transfer can be beneficial or detrimental. Uncontrolled air infiltration from poor weatherization / weatherstripping / draft-proofing can contribute up to 40% of heat loss during winter;[10] however, strategic placement of operable windows or vents can enhance convection, cross-ventilation, and summer cooling when the outside air is of a comfortable temperature and relative humidity.[11] Filtered energy recovery ventilation systems may be useful to eliminate undesirable humidity, dust, pollen, and microorganisms in unfiltered ventilation air. Natural convection causing rising warm air and falling cooler air can result in an uneven stratification of heat. This may cause uncomfortable variations in temperature in the upper and lower conditioned space, serve as a method of venting hot air, or be designed in as a naturalconvection air-flow loop for passive solar heat distribution and temperature equalization. Natural human cooling by perspiration and evaporation may be facilitated through natural or forced convective air movement by fans, but ceiling fans can disturb the stratified insulating air layers at the top of a room, and accelerate heat transfer from a hot attic, or through nearby windows. In addition, high relative humidityinhibits evaporative cooling by humans.

Radiative heat transfer[edit] The main source of heat transfer is radiant energy, and the primary source is the sun. Solar radiation occurs predominantly through the roof and windows (but also through walls). Thermal radiation moves from a warmer surface to a cooler one. Roofs receive the majority of the solar radiation delivered to a house. A cool roof, or green roof in addition to a radiant barrier can help prevent your attic from becoming hotter than the peak summer outdoor air temperature[12] (see albedo, absorptivity, emissivity, andreflectivity). Windows are a ready and predictable site for thermal radiation.[13] Energy from radiation can move into a window in the day time, and out of the same window at night. Radiation uses photons to transmit electromagnetic waves through a vacuum, or translucent medium. Solar heat gain can be significant even on cold clear days. Solar heat gain through windows can be reduced by insulated glazing, shading, and orientation. Windows are particularly difficult to insulate compared to roof and walls. Convective heat transfer through and around window coverings also degrade its insulation properties.[13] When shading windows, external shading is more effective at reducing heat gain than internal window coverings.[13] Western and eastern sun can provide warmth and lighting, but are vulnerable to overheating in summer if not shaded. In contrast, the low midday sun readily admits light and warmth during the winter, but can be easily shaded with appropriate length overhangs or angled louvres during summer and leaf bearing summer shade trees which shed their leaves in the fall. The amount of radiant heat received is related to the location latitude, altitude, cloud cover, and seasonal / hourly angle of incidence (see Sun path andLambert's cosine law).

Another passive solar design principle is that thermal energy can be stored in certain building materials and released again when heat gain eases to stabilize diurnal (day/night) temperature variations. The complex interaction of thermodynamic principles can be counterintuitive for firsttime designers. Precise computer modeling can help avoid costly construction experiments.

Site specific considerations during design[edit]  

Latitude, sun path, and insolation (sunshine) Seasonal variations in solar gain e.g. cooling or heating degree days, solar insolation, humidity



Diurnal variations in temperature



Micro-climate details related to breezes, humidity, vegetation and land contour



Obstructions / Over-shadowing - to solar gain or local cross-winds

Design elements for residential buildings in temperate climates[edit]     

Placement of room-types, internal doors and walls, and equipment in the house. Orienting the building to face the equator (or a few degrees to the East to capture the morning sun)[8] Extending the building dimension along the east/west axis Adequately sizing windows to face the midday sun in the winter, and be shaded in the summer. Minimising windows on other sides, especially western windows [13]



Erecting correctly sized, latitude-specific roof overhangs,[14] or shading elements (shrubbery, trees, trellises, fences, shutters, etc.)[15]



Using the appropriate amount and type of insulation including radiant barriers and bulk insulation to minimise seasonal excessive heat gain or loss



Using thermal mass to store excess solar energy during the winter day (which is then reradiated during the night)[16]

The precise amount of equator-facing glass and thermal mass should be based on careful consideration of latitude, altitude, climatic conditions, and heating/cooling degree dayrequirements. Factors that can degrade thermal performance:  

Deviation from ideal orientation and north/south/east/west aspect ratio Excessive glass area ("over-glazing") resulting in overheating (also resulting in glare and fading of soft furnishings) and heat loss when ambient air temperatures fall

    

Installing glazing where solar gain during the day and thermal losses during the night cannot be controlled easily e.g. West-facing, angled glazing, skylights [17] Thermal losses through non-insulated or unprotected glazing Lack of adequate shading during seasonal periods of high solar gain (especially on the West wall) Incorrect application of thermal mass to modulate daily temperature variations Open staircases leading to unequal distribution of warm air between upper and lower floors as warm air rises



High building surface area to volume - Too many corners



Inadequate weatherization leading to high air infiltration

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Lack of, or incorrectly installed, radiant barriers during the hot season. (See also cool roof and green roof)

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Insulation materials that are not matched to the main mode of heat transfer (e.g. undesirable convective/conductive/radiant heat transfer)

Efficiency and economics of passive solar heating [edit]

Darmstadt University of Technology in Germanywon the 2007 Solar Decathlon in Washington, D.C.with this passive house designed specifically for the humid and hot subtropical climate.[18]

Technically, PSH is highly efficient. Direct-gain systems can utilize (i.e. convert into "useful" heat) 65-70% of the energy of solar radiation that strikes the aperture or collector. Passive solar fraction (PSF) is the percentage of the required heat load met by PSH and hence represents potential reduction in heating costs. RETScreen International has reported a PSF of 20-50%. Within the field of sustainability, energy conservation even of the order of 15% is considered substantial. Other sources report the following PSFs: 

5-25% for modest systems



40% for "highly optimized" systems



Up to 75% for "very intense" systems

In favorable climates such as the southwest United States, highly optimized systems can exceed 75% PSF.[19] For more information see Solar Air Heat

Key passive solar building design concepts[edit] There are six primary passive solar energy configurations:[20] 

direct solar gain



indirect solar gain



isolated solar gain



heat storage



insulation and glazing



passive cooling

Direct solar gain[edit] Direct gain attempts to control the amount of direct solar radiation reaching the living space. This direct solar gain is a critical part of passive solar house designation as it imparts to a direct gain. The cost effectiveness of these configurations are currently being investigated in great detail and are demonstrating promising results.[21]

Indirect solar gain[edit] Indirect gain attempts to control solar radiation reaching an area adjacent but not part of the living space. Heat enters the building through windows and is captured and stored inthermal mass (e.g. water tank, masonry wall) and slowly transmitted indirectly to the building through conduction and convection. Efficiency can suffer from slow response (thermal lag) and heat losses at night. Other issues include the cost of insulated glazing and developing effective systems to redistribute heat throughout the living area.

Isolated solar gain[edit] Isolated gain involves utilizing solar energy to passively move heat from or to the living space using a fluid, such as water or air by natural convection or forced convection. Heat gain can occur through a sunspace, solarium or solar closet. These areas may also be employed usefully as a greenhouse or drying cabinet. An equator-side sun room may have its exterior windows higher than the windows between the sun room and the interior living space, to allow the low winter sun to penetrate to the cold side of adjacent rooms. Glass placement and overhangs prevent solar gain during the summer. Earth cooling tubes or other passive cooling techniques can keep a solarium cool in the summer. Measures should be taken to reduce heat loss at night e.g. window coverings or movable window insulation. Examples: 

Thermosiphon



Barra system



Double envelope house



Thermal buffer zone[22]

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Solar space heating system

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Solar chimney

Heat storage[edit] The sun doesn't shine all the time. Heat storage, or thermal mass, keeps the building warm when the sun can't heat it. In diurnal solar houses, the storage is designed for one or a few days. The usual method is a custom-constructed thermal mass. This includes a Trombe wall, a ventilated concrete floor, a cistern, water wall or roof pond. It is also feasible to use the thermal mass of the earth itself, either as-is or by incorporation into the structure by banking or using rammed earth as a structural medium.[23] In subarctic areas, or areas that have long terms without solar gain (e.g. weeks of freezing fog), purpose-built thermal mass is very expensive. Don Stephens pioneered an experimental technique to use the ground as thermal mass large enough for annualized heat storage. His designs run an isolated thermosiphon 3 m under a house, and insulate the ground with a 6 m waterproof skirt.[24]

Insulation[edit] Main article: Building insulation Thermal insulation or superinsulation (type, placement and amount) reduces unwanted leakage of heat.[9] Some passive buildings are actually constructed of insulation.

Special glazing systems and window coverings [edit] Main articles: Insulated glazing and Window covering The effectiveness of direct solar gain systems is significantly enhanced by insulative (e.g. double glazing), spectrally selective glazing (low-e), or movable window insulation (window quilts, bifold interior insulation shutters, shades, etc.).[25] Generally, Equator-facing windows should not employ glazing coatings that inhibit solar gain. There is extensive use of super-insulated windows in the German Passive House standard. Selection of different spectrally selective window coating depends on the ratio of heating versus cooling degree days for the design location.

Glazing selection[edit] Equator-facing glass[edit] The requirement for vertical equator-facing glass is different from the other three sides of a building. Reflective window coatings and multiple panes of glass can reduce useful solar gain. However, direct-gain systems are more dependent on double or triple glazing to reduce heat loss. Indirect-gain and isolated-gain configurations may still be able to function effectively with only single-pane glazing. Nevertheless, the optimal cost-effective solution is both location and system dependent. Roof-angle glass / Skylights[edit] Skylights admit harsh direct overhead sunlight and glare[26] either horizontally (a flat roof) or pitched at the same angle as the roof slope. In some cases, horizontal skylights are used with reflectors to increase the intensity of solar radiation (and harsh glare), depending on the roof angle of incidence. When the winter sun is low on the horizon, most solar radiation reflects off of roof angled glass ( the angle of incidence is nearly parallel to roof-angled glass morning and afternoon ). When the summer sun is high, it is nearly perpendicular to roof-angled glass,

which maximizes solar gain at the wrong time of year, and acts like a solar furnace. Skylights should be covered and well-insulated to reducenatural convection ( warm air rising ) heat loss on cold winter nights, and intense solar heat gain during hot spring/summer/fall days. The equator-facing side of a building is south in the northern hemisphere, and north in the southern hemisphere. Skylights on roofs that face away from the equator provide mostly indirect illumination, except for summer days when the sun rises on the non-equator side of the building (depending on latitude). Skylights on east-facing roofs provide maximum direct light and solar heat gain in the summer morning. West-facing skylights provide afternoon sunlight and heat gain during the hottest part of the day. Some skylights have expensive glazing that partially reduces summer solar heat gain, while still allowing some visible light transmission. However, if visible light can pass through it, so can some radiant heat gain (they are both electromagnetic radiation waves). You can partially reduce some of the unwanted roof-angled-glazing summer solar heat gain by installing a skylight in the shade of deciduous (leaf-shedding) trees, or by adding a movable insulated opaque window covering on the inside or outside of the skylight. This would eliminate the daylight benefit in the summer. If tree limbs hang over a roof, they will increase problems with leaves in rain gutters, possibly cause roof-damaging ice dams, shorten roof life, and provide an easier path for pests to enter your attic. Leaves and twigs on skylights are unappealing, difficult to clean, and can increase the glazing breakage risk in wind storms. "Sawtooth roof glazing" with vertical-glass-only can bring some of the passive solar building design benefits into the core of a commercial or industrial building, without the need for any roofangled glass or skylights. Skylights provide daylight. The only view they provide is essentially straight up in most applications. Well-insulated light tubes can bring daylight into northern rooms, without using a skylight. A passive-solar greenhouse provides abundant daylight for the equator-side of the building. Infrared thermography color thermal imaging cameras ( used in formal energy audits ) can quickly document the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day. The U.S. Department of Energy states: "vertical glazing is the overall best option for sunspaces."[27] Roof-angled glass and sidewall glass are not recommended for passive solar sunspaces. The U.S. DOE explains drawbacks to roof-angled glazing: Glass and plastic have little structural strength. When installed vertically, glass (or plastic) bears its own weight because only a small area (the top edge of the glazing) is subject to gravity. As the glass tilts off the vertical axis, however, an increased area (now the sloped cross-section) of the glazing has to bear the force of gravity. Glass is also brittle; it does not flex much before breaking. To counteract this, you usually must increase the thickness of the glazing or increase the number of structural supports to hold the glazing. Both increase overall cost, and the latter will reduce the amount of solar gain into the sunspace. Another common problem with sloped glazing is its increased exposure to the weather. It is difficult to maintain a good seal on roof-angled glass in intense sunlight. Hail, sleet, snow, and wind may cause material failure. For occupant safety, regulatory agencies usually require sloped glass to be made of safety glass, laminated, or a combination thereof, which reduce solar gain potential. Most of the roof-angled glass on the Crowne Plaza Hotel Orlando Airport sunspace was destroyed in a single windstorm. Roof-angled glass increases construction cost, and can increase insurance premiums. Vertical glass is less susceptible to weather damage than roofangled glass. It is difficult to control solar heat gain in a sunspace with sloped glazing during the summer and even during the middle of a mild and sunny winter day. Skylights are the antithesis of zero energy building Passive Solar Cooling in climates with an air conditioning requirement. Angle of incident radiation[edit]

The amount of solar gain transmitted through glass is also affected by the angle of the incident solar radiation. Sunlight striking glass within 20 degrees of perpendicular is mostly transmitted through the glass, whereas sunlight at more than 35 degrees from perpendicular is mostly reflected[28] All of these factors can be modeled more precisely with a photographic light meter and a heliodon or optical bench, which can quantify the ratio of reflectivity to transmissivity, based on angle of incidence. Alternatively, passive solar computer software can determine the impact of sun path, and cooling-and-heating degree days on energy performance. Regional climatic conditions are often available from local weather services.

Operable shading and insulation devices[edit] A design with too much equator-facing glass can result in excessive winter, spring, or fall day heating, uncomfortably bright living spaces at certain times of the year, and excessive heat transfer on winter nights and summer days. Although the sun is at the same altitude 6-weeks before and after the solstice, the heating and cooling requirements before and after the solstice are significantly different. Heat storage on the Earth's surface causes "thermal lag." Variable cloud cover influences solar gain potential. This means that latitude-specific fixed window overhangs, while important, are not a complete seasonal solar gain control solution. Control mechanisms (such as manual-or-motorized interior insulated drapes, shutters, exterior roll-down shade screens, or retractable awnings) can compensate for differences caused by thermal lag or cloud cover, and help control daily / hourly solar gain requirement variations. Home automation systems that monitor temperature, sunlight, time of day, and room occupancy can precisely control motorized window-shading-and-insulation devices.

Exterior colors reflecting - absorbing[edit] Materials and colors can be chosen to reflect or absorb solar thermal energy. Using information on a Color for electromagnetic radiation to determine its thermal radiationproperties of reflection or absorption can assist the choices. See Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory: "Cool Colors"

Landscaping and gardens[edit] Main article: Energy-efficient landscaping Energy-efficient landscaping materials for careful passive solar choices include hardscape building material and "softscape" plants. The use of landscape design principles for selection of trees, hedges, and trellis-pergola features with vines; all can be used to create summer shading. For winter solar gain it is desirable to use deciduous plants that drop their leaves in the autumn gives year round passive solar benefits. Nondeciduous evergreen shrubs and trees can be windbreaks, at variable heights and distances, to create protection and shelter from winter wind chill. Xeriscaping with 'mature size appropriate' native species of-and drought tolerant plants, drip irrigation, mulching, and organic gardening practices reduce or eliminate the need for energy-and-water-intensive irrigation, gas powered garden equipment, and reduces the landfill waste footprint. Solar powered landscape lighting and fountain pumps, and covered swimming pools and plunge pools with solar water heaters can reduce the impact of such amenities. 

Sustainable gardening



Sustainable landscaping



Sustainable landscape architecture

Other passive solar principles[edit] Passive solar lighting[edit] Main article: Passive solar lighting Passive solar lighting techniques enhance taking advantage of natural illumination for interiors, and so reduce reliance on artificial lighting systems. This can be achieved by careful building design, orientation, and placement of window sections to collect light. Other creative solutions involve the use of reflecting surfaces to admit daylight into the interior of a building. Window sections should be adequately sized, and to avoid overillumination can be shielded with a Brise soleil, awnings, well placed trees, glass coatings, and other passive and active devices.[20] Another major issue for many window systems is that they can be potentially vulnerable sites of excessive thermal gain or heat loss. Whilst high mounted clerestory window and traditional skylights can introduce daylight in poorly oriented sections of a building, unwanted heat transfer may be hard to control.[29][30] Thus, energy that is saved by reducing artificial lighting is often more than offset by the energy required for operating HVAC systems to maintain thermal comfort. Various methods can be employed to address this including but not limited to window coverings, insulated glazing and novel materials such as aerogel semi-transparent insulation, optical fiber embedded in walls or roof, or hybrid solar lighting at Oak Ridge National Laboratory. Reflecting elements, from active and passive daylighting collectors, such as light shelves, lighter wall and floor colors, mirrored wall sections, interior walls with upper glass panels, and clear or translucent glassed hinged doors and sliding glass doors take the captured light and passively reflect it further inside. The light can be from passive windows or skylights and solar light tubes or from active daylighting sources. In traditional Japanese architecture the Shōji sliding panel doors, with translucent Washi screens, are an original precedent. International style, Modernist and Midcentury modern architecture were earlier innovators of this passive penetration and reflection in industrial, commercial, and residential applications.

Passive solar water heating[edit] Main article: Solar hot water There are many ways to use solar thermal energy to heat water for domestic use. Different active-and-passive solar hot water technologies have different location-specific economic cost benefit analysis implications. Fundamental passive solar hot water heating involves no pumps or anything electrical. It is very cost effective in climates that do not have lengthy sub-freezing, or very-cloudy, weather conditions.[31] Other active solar water heating technologies, etc. may be more appropriate for some locations. It is possible to have active solar hot water which is also capable of being "off grid" and qualifies as sustainable. This is done by the use of a photovoltaic cell which uses energy from the sun to power the pumps.[citation needed]

Comparison to the Passive House standard in Europe[edit] Main article: Passive house There is growing momentum in Europe for the approach espoused by the Passive House (Passivhaus in German) Institute in Germany. Rather than relying solely on traditional passive solar design techniques, this approach seeks to make use of all passive sources of heat, minimises energy usage, and emphasises the need for high levels of insulation reinforced by meticulous attention to detail in order to address thermal bridging and cold air infiltration. Most of the buildings built to the Passive House standard also incorporate an active heat recovery ventilation unit with or without a small (typically 1 kW) incorporated heating component.

The energy design of Passive House buildings is developed using a spreadsheet-based modeling tool called the Passive House Planning Package (PHPP) which is updated periodically. The current version is PHPP2007, where 2007 is the year of issue. A building may be certified as a "Passive House" when it can be shown that it meets certain criteria, the most important being that the annual specific heat demand for the house should not exceed 15kWh/m 2a.

Design tools[edit] Traditionally a heliodon was used to simulate the altitude and azimuth of the sun shining on a model building at any time of any day of the year.[32] In modern times, computer programs can model this phenomenon and integrate local climate data (including site impacts such as overshadowing and physical obstructions) to predict the solar gain potential for a particular building design over the course of a year. GPS-based smartphone applications can now do this inexpensively on a hand held device. These design tools provide the passive solar designer the ability to evaluate local conditions, design elements and orientation prior to construction. Energy performance optimization normally requires an iterative-refinement design-and-evaluate process. There is no such thing as a "one-size-fits-all" universal passive solar building design that would work well in all locations.

Levels of application[edit] Many detached suburban houses can achieve reductions in heating expense without obvious changes to their appearance, comfort or usability.[33] This is done using good siting and window positioning, small amounts of thermal mass, with good-but-conventional insulation, weatherization, and an occasional supplementary heat source, such as a central radiator connected to a (solar) water heater. Sunrays may fall on a wall during the daytime and raise the temperature of its thermal mass. This will then radiate heat into the building in the evening. External shading, or a radiant barrier plus air gap, may be used to reduce undesirable summer solar gain. An extension of the "passive solar" approach to seasonal solar capture and storage of heat and cooling. These designs attempt to capture warm-season solar heat, and convey it to a seasonal thermal store for use months later during the cold season ("annualised passive solar.") Increased storage is achieved by employing large amounts of thermal mass or earth coupling. Anecdotal reports suggest they can be effective but no formal study has been conducted to demonstrate their superiority. The approach also can move cooling into the warm season. Examples: 

Passive Annual Heat Storage (PAHS) - by John Hait

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Annualized Geothermal Solar (AGS) heating - by Don Stephen

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Earthed-roof

A "purely passive" solar-heated house would have no mechanical furnace unit, relying instead on energy captured from sunshine, only supplemented by "incidental" heat energy given off by lights, computers, and other task-specific appliances (such as those for cooking, entertainment, etc.), showering, people and pets. The use of natural convection air currents (rather than mechanical devices such as fans) to circulate air is related, though not strictly solar design. Passive solar building design sometimes uses limited electrical and mechanical controls to operate dampers, insulating shutters, shades, awnings, or reflectors. Some systems enlist small fans or solar-heated chimneys to improve convective air-flow. A reasonable way to analyse these systems is by measuring their coefficient of performance. A heat pump might use 1 J for every 4 J it delivers giving a COP of 4. A system that only uses a 30 W fan to more-evenly distribute 10 kW of solar heat through an entire house would have a COP of 300. Passive solar building design is often a foundational element of a cost-effective zero energy building.[34][35] Although a ZEB uses multiple passive solar building design concepts, a ZEB is usually not purely passive, having active mechanical renewable energy generation systems such

as: wind turbine, photovoltaics, micro hydro, geothermal, and other emerging alternative energy sources.

What Is the Difference Between Active & Passive Solar Collectors? by Karyn Maier, Demand Media

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Windows act as collectors in a passive solar design, while active solar systems use additional equipment.

The use of solar radiation for energy is an ancient concept, but recent concerns about the environmental impact of burning fossil fuels have made solar energy a hot topic. Modern solar energy technologies harness the heat generated from the sun to power residential and industrial heating and cooling systems through the use of photovoltaic, or PV, panels. Also known as solar cells, these devices capture and convert solar power into electrical energy. How this energy is collected and distributed defines the difference between active and passive solar collectors.

Passive Solar Design A passive solar system does not involve mechanical devices or the use of conventional energy sources beyond that needed to regulate dampers and other controls, if any. Classic examples of basic passive solar structures are greenhouses, sunrooms and solariums -- as the sun's rays pass through the glass windows, the interior absorbs and retains the heat. Modeling this concept in your home can cut heating costs by half compared to heating the same home by traditional means without the use of passive solar (see References 1). In terms of design, success of the passive solar system depends on orientation and the thermal mass of the

structure's exterior walls, which means their ability to store and redistribute heat (see References 2).

Passive Solar Collectors A passive solar system typically relies on south-facing windows as collectors to capture solar energy, although some systems may also use supplemental PV panels. In any case, the goal is to redistribute the energy collected according to a fundamental law of thermodynamics, which states that heat moves from warm to cool areas and surfaces (see References 3). The simplest method of transferring the heat from passive solar collectors is through convection. To illustrate, think of a sunroom with windows on a southern wall. As the sun's rays travel through the glass, the heat is directed into the room. It then rises to areas where the air is cooler, including other rooms beyond and above.

Energy management From Wikipedia, the free encyclopedia

Energy management includes planning and operation of energy production and energy consumption units. Objectives are resource conservation, climate protection and cost savings, while the users have permanent access to the energy they need. It is connected closely to environmental management, production management, logistics and other established business functions. The VDI-Guideline 4602 released a definition which includes the economic dimension: “Energy management is the proactive, organized and systematic coordination of procurement, conversion, distribution and use of energy to meet the requirements, taking into account environmental and economic objectives”.[1] Contents [hide]

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1 Organizational integration

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2 Energy management in operational functions o

2.1 Facility management

o

2.2 Logistics

o

2.3 Energy procurement

o

2.4 Production

o

2.5 Production planning and control

o

2.6 Maintenance

o

2.7 Information technology

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3 Energy strategies o

3.1 Potential energy strategies

o

3.2 Energy strategies of companies

o

3.3 Energy strategies of politics

o

3.4 Ethical and normative basis of the energy strategies

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4 See also

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5 External links



6 References

Organizational integration[edit] It is important to integrate the energy management in the organizational structure, so that the energy management can be implemented. Responsibilities and the interaction of the decision makers should be regularized. The delegation of functions and competencies extend from the top management to the executive worker. Furthermore, a comprehensive coordination can ensure the fulfillment of the tasks. It is advisable to establish a separate organizational unit “energy management” in large or energy-intensive companies. This unit supports the senior management and keeps track. It depends on the basic form of the organizational structure, where this unit is connected. In case of a functional organization the unit is located directly between the first (CEO) and the second hierarchical level (corporate functions such as production, procurement, marketing). In a divisional organization, there should be a central and several sector-specific energy management units. So the diverse needs of the individual sectors and the coordination between the branches and the head office can be fulfilled. In amatrix organization the energy management can be included as a matrix function and thus approach most functions directly.

Energy management in operational functions[edit] Facility management[edit] Facility management is an important part of energy management, because a huge proportion (average 25 per cent) of complete operating costs are energy costs. According to the International Facility Management Association (IFMA), facility management is "a profession that encompasses multiple disciplines to ensure functionality of the built environment by integrating people, place, processes and technology." The central task of energy management is to reduce costs for the provision of energy in buildings and facilities without compromising work processes. Especially the availability and service life of the equipment and the ease of use should remain the same. The German Facility Management Association (GEFMA e.V.) has published guidelines (e.g. GEFMA 124-1 and 124-2), which contain methods and ways of dealing with the integration of energy management in the context of a successful facility management.[2] In this topic the facility manager has to deal with economic, ecological, risk-based and quality-based targets. He tries to minimize the total cost of the energyrelated processes (supply, distribution and use). [3]

The Passivhaus uses a combination of low-energy building techniques and technologies.

The most important key figure in this context is kilowatt-hours per square meter per year (kWh/m²a). Based on this key figure properties can be classified according to their energy consumption. 

Europe: In Germany a low-energy house can have a maximum energy consumption of 70 kWh/m²a.



North America: In the United States, the ENERGY STAR program is the largest program defining low-energy homes. Homes earning ENERGY STAR certification use at least 15% less energy than standard new homes built to the International Residential Code, although homes typically achieve 20%-30% savings.[4]

In comparison, the Passive house (Passivhaus in German) ultra-low-energy standard, currently undergoing adoption in some other European countries, has a maximum space heating requirement of 15 kWh/m²a. A Passive House is a very well-insulated and virtually air-tight building. It does not require a conventional heating system. It is heated by solar gain and internal gains from people. Energy losses are minimized. [5] There are also buildings that produce more energy (for example by solar water heating or photovoltaic systems) over the course of a year than it imports from external sources. These buildings are called energy-plus-houses.[6] In addition, the work regulations manage competencies, roles and responsibilities. Because the systems also include risk factors (e.g., oil tanks, gas lines), you must ensure that all tasks are clearly described and distributed. A clear regulation can help to avoid liability risks. [7]

Logistics[edit]

Carriage of goods

Logistics is the management of the flow of resources between the point of origin and the point of destination in order to meet some requirements, for example of customers or corporations. Especially the core logistics task, transportation of the goods, can save costs and protect the environment through efficient energy management. The relevant factors are the choice of means of transportation, duration and length of transportation and cooperation with logistics service providers. The logistics causes more than 14% percent of CO2 emissions worldwide. For this reason the term Green Logistics is becoming increasingly important. Possible courses of action in terms of green logistics are:[8] 

Shift to ecofriendly transport carrier such as railroad and waterway

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Route and load optimization

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Formation of corporate networks, which are connected by logistics service



Optimizing physical logistics processes by providing a sophisticated IT support

Besides transportation of goods, the transport of persons should be an important part of the logistic strategy of organizations. In case of business trips it is important to attract attention to the choice and the proportionality of the means of transport. It should be balanced whether a physical presence is mandatory or a telephone or video conference is just as useful. Home Office is another possibility in which the company can protect the environment indirectly.[9]

Energy procurement[edit] Procurement is the acquisition of goods or services. Energy prices fluctuate constantly, which can significantly affect the energy bill of organizations. Therefore poor energy procurement decisions can be expensive. Organizations can control and reduce energy costs by taking a proactive and efficient approach to buying energy. Even a change of the energy source can be a profitable and eco-friendly alternative.[10]

Production[edit] Production is the act of creating output, a good or service which has value and contributes to the utility of individuals.[11] This central process may differ depending on the industry. Industrial companies have facilities that require a lot of energy. Service companies, in turn, do not need many materials, their energy-related focus is mainly facility management or Green IT. Therefore the energy-related focus has to be identified first, then evaluated and optimized.

Production planning and control[edit] Usually, production is the area with the largest energy consumption within an organization. Therefore also the production planning and control becomes very important. It deals with the operational, temporal, quantitative and spatial planning, control and management of all processes that are necessary in the production of goods and commodities. The "production planner" should plan the production processes so that they operate on an energy efficient way. For example, strong power consumer can be moved into the night time. Peaks should be avoided for the benefit of a unified load profile. The impending changes in the structure of energy production require an increasing demand for storage capacity. The Production planning and control has to deal with the problem of limited storability of energy. In principle there is the possibility to store energy electrically, mechanically or chemically. Another trend-setting technology is lithium-based electrochemical storage, which can be used in electric vehicles or as an option to control the power grid. The German Federal Ministry of Economics and Technology realized the significance of this topic and established an initiative with the aim to promote technological breakthroughs and support the rapid introduction of new energy storage.[12]

Maintenance[edit] Maintenance is the combination of all technical and administrative actions, including supervision actions, intended to retain an item in, or restore it to, a state in which it can perform a required function.[13] Detailed maintenance is essential to support the energy management. Hereby power losses and cost increases can be avoided.[14] Examples of how it is possible to save energy and costs with the help of maintenance: 

Defrost the fridges



Check the barometer of cars and trucks



Insulation of hot systems



Improve leaks in building envelopes

Information technology[edit] The center of an environmental and resource saving structure of information technology is Green IT. In the article Harnessing Green IT: Principles and Practices, San Murugesan defines the field of green computing as "the study and practice of designing, manufacturing, using, and disposing of computers, servers, and associated subsystems—such as monitors, printers, storage devices, and networking and communications systems — efficiently and effectively with minimal or no impact on the environment.”[15] This includes the optimization of resource consumption during manufacturing, operation and disposing of computers. With the help of IT, work processes can be eliminated or improved energetically.[16] Approaches: 

Production of devices: You should make sure that the equipment was manufactured resource-conserving and consume less power than comparable devices.



Purchase and operation of equipment: Energy Star is an international standard for energy efficient consumer products originated in the United States of America. The Energy Star label can help to identify energy efficient devices. Important elements are for example more efficient power adapter, a modern stand-by and sleep mode. [17]



IT support: Many programs support organizations to conserve energy. This includes large ERP systems as well as the IT support of small systems. There are also commercial energy management systems.

Energy strategies[edit] A long-term energy strategy should be part of the overall strategy of a company. This strategy may include the objective of increasing the use of renewable energies. Furthermore, criteria for decisions on energy investments, such as yield expectations, are determined. [18] By formulating an energy strategy companies have the opportunity to avoid risks and to assure a competitive advance against their business rivals.[19]

Potential energy strategies[edit] According to Kals there are the following energy strategies:[20] 

Passive Strategy: There is no systematic planning. The issue of energy and environmental management is not perceived as an independent field of action. The organization only deals with the most essential subjects.



Strategy of short-term profit maximization: The management is concentrating exclusively on measures that have a relatively short payback period and a high return. Measures with low profitability are not considered.



Strategy of long-term profit maximization: This strategy includes that you have a high knowledge of the energy price and technology development. The relevant measures (for example, heat exchangers or power stations) can have durations of several decades. Moreover, these measures can help to improve the image and increase the motivationof the employees.



Realization of all financially attractive energy measures: This strategy has the goal to implement all measures that have a positive return on investment.



Maximum strategy: For the climate protection one is willing to change even the object of the company.

In reality, you usually find hybrid forms of different strategies.

Energy strategies of companies[edit] Many companies are trying to promote its image and time protect the climate through a proactive and public energy strategy. General Motors (GM) strategy is based on continuous improvement. Furthermore they have six principles: e.g. restoring and preserving the environment, reducing waste and pollutants, educating the public about environmental conservation, collaboration for the development of environmental laws and regulations.[21] Nokia created its first climate strategy in 2006. The strategy tries to evaluate the energy consumption and greenhouse gas emissions of products and operations and sets reduction targets accordingly.[22] Furthermore, their environmental efforts is based on four key issues: substance management, energy efficiency, recycling, promoting environmental sustainability.[23] The energy strategy of Volkswagen (VW) is based on environmentally friendly products and a resource-efficient production according to the "Group Strategy 2018". [24] Almost all locations the of the Group are certified to the international standard ISO 14001 for environmental management systems.[25] When looking at the energy strategies of companies it is important to you have the topic greenwashing in mind. This is a form of propaganda in which green strategies are used to promote the opinion that an organization's aims are environmentally friendly.[26]

Energy strategies of politics[edit] Even many countries formulate energy strategies. The Swiss Federal Council decided in May 2011 to resign nuclear energy medium-dated. The nuclear power plants will be shut down at the end of life and will not be replaced. In Compensation they put the focus on energy efficiency, renewable energies, fossil energy sources and the development ofwater power.[27] The European Union has clear instructions for its members. The "20-20-20-targets" include, that the Member States have to reduce greenhouse gas emissions by 20% below 1990 levels, increase energy efficiency by 20% and achieve a 20% share of renewable energy in total energy consumption by 2020.[28]

Ethical and normative basis of the energy strategies [edit]

The basis of every energy strategy is the corporate culture and the related ethical standards applying in the company.[29] Ethics, in the sense of business ethics, examines ethical principles and moral or ethical issues that arise in a business environment. Ethical standards can appear in company guidelines, energy and environmental policies or other documents. The most relevant ethical ideas for the energy management are: 

Utilitarianism: This form of ethics has the maxim that the one acts are good or right, whose consequences are optimal for the welfare of all those affected by the action (principle of maximum happiness). In terms of energy management, the existence of external costs should be considered. They do not directly affect those who profit from the economic activity but non-participants like future generations. This error in the market mechanism can be solved by the internalization of external costs.[30]



Argumentation Ethics: This fundamental ethical idea says that everyone who is affected by the decision, must be involved in decision making. This is done in a fair dialogue, the result is completely uncertain.[31]



Deontological ethics: The deontological ethics assigns individuals and organizations certain obligations. A general example is the golden rule: "One should treat others as one would like others to treat oneself." Therefore everyone should manage their duties and make an energy economic contribution.[31]