ENERGY CONSERVATION STRATEGIES: TOTAL BUILDING PERFORMANCE CONCEPT FROM OCCUPANT’S PERSPECTIVE

Energy Conservation Strategies: Total Building Performance Concept from Occupant’s Perspective

ENERGY CONSERVATION STRATEGIES: TOTAL BUILDING PERFORMANCE CONCEPT FROM OCCUPANT’S PERSPECTIVE Norishahaini M. Ishak, Farrah Zuhaira Ismail, Mohd. Reza Esa and Zarina Yasmin Hanur Harith Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA, Shah Alam, MALAYSIA [email protected] ABSTRACT: Numerous numbers of energy conservation strategies were implemented with neither sufficient consideration of building performance nor occupancy needs and this has lead to many failures in building performance. In Malaysia, most of the new commercial buildings are built with an adoption of various energy conservation strategies particularly in passive and active design consideration. This paper explores energy conservation strategies adopted by the Ministry of Energy, Water and Communication building in Putrajaya and the impact towards the occupants under the concept of total building performance (TBP). The objectives of TBP are; to achieve overall quality of a building in terms of its six performance mandates (thermal, indoor air quality, acoustic, visual, spatial and building integrity) and the integration within the building system. The integration is expanded through satisfying the occupancy needs by defining the physiological, psychological, sociological and economical requirements. The occupant’s perception towards the energy conservation strategies were evaluated using subjective measurement method based on the TBP mandates. From the results, the overall performance were rated as ‘satisfactory’ and above for thermal comfort, indoor air quality, visual, acoustic, spatial and building integrity by 91.9%, 94.6%, 97.4%, 100%, 100% and 100% respectively. Keywords: Total building performance; commercial building; occupant’s perception; energy conservation strategy

1.

INTRODUCTION

Energy conservation became prominent in the 1980s, after the oil crisis. Since then, a number of activities have been initiated to create a greater awareness of energy conservation. This includes the use of renewable energy and energy efficiency legislative framework for the commercial sector primarily in the government building. The growth in energy demand for building has become an important issue in Malaysia. The commercial sector particularly has consumed about 29% of the national electricity consumption (MEWC, 2003). Owing to Malaysia’s predominantly humid weather condition, about 40% of the total energy demand in the commercial sector is used for space cooling, thus energy conservation strategies for these buildings should focus on energy efficiency for space cooling. Dubin (1977) stated several ways in implementing the energy conservation strategies in buildings. This includes analysis of climate, building structure, mechanical and electrical system and building functions as well as building operations which directly affect the energy consumption. The analysis provides a stimulus to the architects and engineers to further incorporate energy conservation in new and existing buildings by implementing energy conservation programs. Any program or strategy adopted should not neglect nor overlook the occupancy needs and the building performance. 377

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The objectives of total building performance are to measure occupant’s satisfaction, health and productivity (Hartkopf and Loftness, 1999). This field has been explored by various researchers in terms of its performance mandates (thermal, visual, indoor air quality, spatial, acoustical and building integrity) and integration within the building system. The integration is expanded through satisfying the occupancy needs by defining the physiological, psychological, sociological and economical requirements. With regard to that, building delivery process is central in establishing the occupancy needs as well as determining the success of integration between various mandates within the building system. The occupant’s productivity however, can be affected by poor building performance which is might be attributed to sick building syndrome. Besides that, building failures can also occur when strong emphasis is given to a specific performance mandates thus; insufficient consideration for the other performance mandates (The Building System and Integration Handbook, 1986). Wong and Jan (2000) reported that the context of TBP itself can be separated into two areas; building enclosure integrity performance - protection of the building’s visual, mechanical, and physical properties from environmental degradation and 2) interior occupancy requirement and the elemental parameters of health, safety, and well being in relation to the thermal, spatial, visual, indoor air, and acoustic comfort of the spaces being designed. They believe that, the concept of TBP might assist the provision of healthy working conditions and facilities that are better customized to the occupant’s needs. The aim of this study is examine the possible impact of energy conservation strategies on the occupants of the Ministry of Energy, Water and Communication’s buildings in Putrajaya in terms of TBP mandates (thermal, acoustic, indoor air quality, visual, spatial and building integrity) that is yet to be explored. Subjective method of measurement was applied to investigate the success of the strategies adopted in the attempt to challenge the current set of local energy efficiency standards for commercial buildings in Malaysia. 2.

METHODOLOGY

The study adopted the same methodology as Wong and Jan (2000). The Ministry of Energy, Water and Communication’s building which is an office building has been chosen as the case study. The information was obtained by various techniques ranging from interviews, walk-through and visual inspection. Subjective measurement was carried out by conducting a survey on MEWC building staffs to assess the six performance criteria i.e. thermal comfort, visual comfort, indoor air quality, acoustical quality, special quality and building integrity. Data obtained from the surveys were statistically analyzed using the SPSS program. 3.

NON RESIDENTIAL DESIGN GUIDELINE – ENERGY EFFICIENCY BUILDING

The MEWC building has been designed according to MS 1525:2001 “Codes of Practice on Energy Efficiency and the Use of Renewable Energy for Non-Residential Buildings” referring to Uniform Building By-Law 1984. Several critical decisions were made in relation to the passive and active

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building designs, constructions and building operations pertaining to the architecture, mechanical and electrical systems, office equipments, landscaping and implementation of energy management systems which are laid under this code of practice. 4.

ENERGY CONSERVATION DESIGN STRATEGY – IMPACTS ON TBP

The MEWC LEO building has adopted both passive and active design features in order to achieve low energy consumption and shown in Table 1. Table 1: Design strategies impacts on performance mandates Possibilities impact on performance mandates Design strategy

A) 1. 2.

3. 4. B)

Passive Design Strategy Building orientation - Day lighting Building envelope - Façade, window, wall, roof Natural ventilation Structural system

Thermal

Indoor air

Spatial

Visual

√

√

√

√

√

√

√

√

√

√

√ √

√ √

3.

Active Design Strategy Lighting system Air-conditioning & mechanical ventilation system Elevator system

5.0

DATA COLLECTION

5.1

SUBJECTIVE MEASUREMENT

1. 2.

√

Acoustic

√ √

√ √ √

√

√ √

Building Integrity

√ √

√

√ √

√ √

√

√

Subjective measurements were carried out based on a survey from the building’s occupant. The sample size for the survey is 74 occupants and they were assumed to have same level of sensitivity to the comfort of the environment.

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6.

DATA ANALYSIS

6.1

Subjective Analysis

6.1.1 Analysis by Expert Walkthrough A physical walkthrough was conducted by the authors together with the manager of energy department to detect any performance stress signs and user modification. Table 2 represents the observation of the various performance mandates. Table 2: Stress sign and user modification in the office Thermal High heat gain through east facing window in the morning.

Air Quality

Spatial

Acoustic

Building integrity

Stale air at some of office area and particularly at the corridor area.

Narrow walkway or corridor to the office room

Less privacy in conversation due to open work system.

Views Minor crack at distraction exterior wall caused by punch hole window. People who sitting at the window’s parameter are distracted with the automatic time-based control lighting and glare problem

Air freshener

Nil

Nil

Nil

Dressing inflexibility High A/C setting point (26°C) at the corridor caused uncomfortable to the occupants Users modification Fans

Visual

Nil

6.1.2 Analysis by Occupant Survey Subjective measurements were taken from the MEWC staff occupying the building in order to assess the energy conservation strategies impact on six major TBP attributes. The survey scale is ranging from 1 to 5 indicates that very poor to excellent condition. The scale of 3 is places on satisfactory or normal condition for the ease of analysis. For the purpose of this study, if 80% or more of the occupants rated the overall environment as 3 or better, the perception of that parameter will be considered as acceptable. Figure 1 shows the perception on the overall comfort rated by the building’s occupants. By looking at the graph, the most or 100 percent rated for satisfactory and above are for acoustic and spatial performance. Whereby for thermal, indoor air and visual quality are lacks by 8.1%, 5.4% and 2.6% respectively. Figure 2 shows the building integrity defects observe by the occupants. Visible cracks were most often observed by the occupants, followed by leakage/staining from pipe or toilet, rusty hinges discoloration and fungus growth by 33%, 22%, 17%, 17% and 11% respectively. This has shown

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Figure 1: Overall performance mandates response.

Figure 2: Defects observed at the building.

that the direct sun exposure to the building had caused crack and discoloration both external and internal of building. Besides that, leakage from air-conditioning duct had caused some stain to ceiling plenum. Figure 3 shows the health problem suffered by the occupant. The most rated health problems is headache and followed by runny nose and dry skin. Besides, most of the occupants have no complication on health problem during occupying the building.

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Figure 3: Health problems suffered by the occupants.

6.1.3 Correlation Analysis The Statistical Package for the Social Sciences (SPSS) programme is used to identify those subparameters that have strong relationships with the dependent variable i.e. TBP mandates. The Pearson correlation test is used in order to determine the highest correlation probabilities of more than 85% and a coefficient of 0.25 and above (refers Table 3). Table 3: Variables significant to TBP of MEWC’s building No 1 2 3 4 5 6 7 8 9 10 11

Variables (AddTh) Additional method for thermal comfort (TempC) Self temperature control (AirF) Air freshness (AirC) Air cleanness (ColF) Colour scheme of interior finishing (Glare) Glare problem (PrvC) Privacy in conversation (NoiseE) Exterior noise level (Space) Office space circulation (Desk) Desk position (OffApp) Office appearance

Coefficient

Probability %

0.31 0.66 0.55 0.43 0.62 0.36 0.33 0.36 0.49 0.43 0.81

98.40 99.99 99.99 99.99 99.99 97.00 96.80 97.80 99.99 99.99 99.99

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6.1.4 Regression Analysis The relationship between dependent and independent variables can be seen by using regression analysis. It is also can determined the best regression model that effect both variables. From Table 4, it can be seen that the best R2 value is 0.79 which indicates that 79% of the variation of total building performance can be jointly explained by six independent variables chosen for the model. The assumptions made are that the variables are independent and random, the model is linear and that the independent variables are not highly correlated. The best model calculated for MEWC’s building is: TBP = 0.26 + 0.52(Space) + 0.37(TempC) + 0.34(AirC) - 0.25(ExtNoise) – 0.24(Glare). It can be seen from the formula that space circulation (Space) contributed most to explaining the variation in R2 model by 0.65. With an intercept of 0.26 for the model, TBP is positive even before the values of variables are entered. The positive variables are also includes space circulation in the building, individual temperature control and air cleanness level that contributes positively to TBP. The TBP is better if more space circulation provided in the building, more individual control on temperature and with good level of air cleanness. Nonetheless, the negative coefficient for ‘ExtNoise’ and ‘Glare’ indicates that the better the control, the worst TBP will be for the room which is no longer logical. The unexpected sign for the regression coefficient might be a problem with multicollinearity in the model with the effect of high correlation among independent variables. Table 4: Variables selected from stepwise method No

Variables

1 2 3 4 5 6

7.

Model R2

(NoiseE)Exterior noise level (TempC) Self temperature control (Glare)Glare problem (AirC)Air cleanness (Space)Office space circulation (OffApp)Office appearance

0.28 0.43 0.61 0.79 0.65 0.65

ACCEPTANCE OF OVERALL EXPERT WALKTHROUGH, SURVEY AND REGRESSION ANALYSIS

The reconciliation of expert walkthrough and survey analysis is to compare whether the surveys respond by the occupants during occupying the building is the direct result of walkthrough analysis. By this, it would bring some idea if detail measurements going to be taken in regards of six total building performance mandates.

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7.1

TBP Mandates

The overall thermal performance rated as satisfactory and above which constitutes 91.9% that agreed upon thermal quality performance. The remaining 8.1% are perhaps rated by the occupants who sitting at the east facing window whose suffer from high heat gains during the morning. Besides, independent variable of individual temperature control (TempC) chosen by SPSS programme is to be significant variables for the TBP of the MEWC’s building. Thus, both analyses are corresponding to each other. For spatial performance, the survey result rated as satisfactory and above with value of 100%. This assessment seems differ with with the walkthrough analysis. The walkway or corridor of the building seems to be narrow and limited spaces for the occupant’s for socialising. Using SPSS, the variables significant to TBP is common, i.e. ‘Space’ and ‘Desk’. Stepwise also selected ‘Space’ to be the variable that contributes most to the TBP MEWC’s building, which means that having sufficient office space circulation affects total building performance the most. For acoustic point of view, it has been rated as 100% (satisfactory and above) towards the overall acoustic variables in the survey. This value also shows some contradiction with the walkthrough investigation. This is because; with the open office work system there is a great issue on occupant’s privacy due to conversation disturbance. This reasons supported by the SPSS variables, i.e. ‘PrivC’ and ‘NoiseE’ and stepwise method chosen ‘NoiseE’ to be variable contributes to TBP. The overall visual quality performance gives 97.4% rated by the occupants. The remaining of 2.6% is likely to be rated by the occupants who suffer from the glare problem. This is also determined by SPSS variables, i.e. ‘Glare’ that contributes more to TBP. Hence, both analyses are correlated to each other. The overall indoor air quality performance rated as satisfactory and above by 94.6% and poor for 5.4%. Based on walkthrough analysis, stale air condition had been found at some building area and this might be due to poor air quality. By looking at the air-conditioning system, this problem can be encountered by looking at the cooling set point and the provision of the supplied air. The SPSS variables, i.e. ‘AddM’ and ‘TempC’ support this reason and stepwise methods choose ‘TempC’ as variable that contributes to TBP. Building integrity is evaluated in terms of defects observed by the occupants either at the interior or exterior of building system. The most rated defect is visible crack at the surface of MEWC’s building. SPSS listed appearance of the office on ‘building integrity’ as a variable significant to TBP. About 97.3% considered the office appearance as normal to excellent level. 8.

CONCLUSION

The energy conservation strategies and its impact on the occupancy needs have been reported in relation to the concept of total building performance. The result gathered from this study can give some ideas to both private and governmental body in Malaysia in adopting energy conservation strategies for new building project particularly during building delivery process. Building performance need to be evaluated holistically rather than focusing to one performance decision because it might lead to other performance failure. Finally, in an attempt to investigate the effectiveness on the energy conservation strategy, it is best to carry out with the objective

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measurements by using appropriate equipment so that it will gives sufficient finding on assessing the impact of energy conservation strategies on the occupants. ACKNOWLEDGEMENTS The author would like to thank Professor Michael Chiew Yit Lin, AP Wong Nyuk Hien, AP Tham Kok Wai and Mr. Kamran Shavarebi Ali for sharing their experiences and guidance in preparing this report. Special thanks to Mr. Abd. Khalid Che Din and Miss Nadrahanim for giving their full collaboration in this study. REFERENCES Dubin, F. (1997). Energy Conservation Studies, Energy and Buildings, 1(1): 31-42. Hartkopf, V. and Loftness, V. (1999). Global relevance of total building performance, Automation in Construction, 8(4): 377-393. Ministry of Energy (2003). Water and Communication. National Energy Balance Malaysia. Rush, R. D. (1986). The Building System Integration Handbook, New York: Wiley. Wong, N. Y. and Jan, W. L. S. (2000). Total building performance evaluation of academic institution in Singapore, Building and Environment, 38; 161-176.

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