ASHRAE Standard 62 and LEED Certification

 ASHRAE Standard 62.1 and LEED Certification Ventilation for Acceptable Indoor Air Quality

Stephen Haines, EIT EIT,, LEED AP JBA Consulting Engineers Mechanical Engineering

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What is ASHRAE Standard 62.1? 

The Industries Ventilation Standard

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Purpose: “… to specify minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health health effects.”  effects.”

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Scope: All commercial, institutional and high-rise residential buildings (excludes low-rise residential)

History of ASHRAE Standard 62.1 1989

Higher Rates (Office – 20 cfm/person)

1981

Lower Rates (Office – 5 cfm/person) 1970

1980

1990

2001

More Mandatory Language

2000

2010

1999 1984

Steve’s birthday

2010

Little Change

Most Current 2004

1973

First Issued (Office – 15 cfm/person)

Key Changes: Ventilation Rate Procedure

2007

Corrections, Clarifications

Key Changes in 62.1-2004  

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 Area-related  Area-relat ed and occupancy-re occupancy-related lated ventilation components Minimum Ventilation Rate Table revised to apply only to non-smoking areas (smoking areas are still not addressed)  Appendix G – Existing Buildings Buildings Equipment replacements, replacements, Substantial Substantial alterations alterations   Additions, Equipment

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Indoor Air Humidity (65% max) and pressure requirements (positive when dehumidifying)

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Requirement to deliver outside air directly to occupied spaces

Why is ASHRAE 62.1 Important? 

It is the basis for many ventilation codes

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More stringent than codes in some cases and helps establish the “standard-of-care standard-of-care””

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Compliance with ASHRAE Standard 62.1-2007 is a prerequisite for any LEED-NC any  LEED-NC credits

Two Paths to Compliance 

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Ventilation Rate Procedure 

Most commonly used method

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Table 6-1 Minimum Ventilation Rates in Breathing Zone

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Need to determine the zone air distribution effectiveness (E z)

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LEED requires this method for compliance

Indoor Air Quality Procedure 

Designed to maintain specific contaminant levels

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Mass balance analysis

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Methods used in similar buildings

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Validation by contaminant monitoring verification

Ventilation Rate Procedure

Ventilation Rate Procedure

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Note the following f ollowing rooms do not require area-based ventilation per ASHRAE Stan dard 62.1-2007: Electrical equipment rooms  Telecommunication elecommunications/data s/data rooms  Elevator machine rooms  Other similar non-occupied spaces 

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Clarified under Interpretation IC 62.1-2007-17 approved on January 23, 2010

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Correction made for Standard 62.1-2010

Ventilation Rate Procedure

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Note the following f ollowing rooms do not require area-based ventilation per ASHRAE Stan dard 62.1-2007: Electrical equipment rooms  Telecommunication elecommunications/data s/data rooms  Elevator machine rooms   Other similar non-occupied spaces

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Clarified under Interpretation IC 62.1-2007-17 approved on January 23, 2010

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Corrected in the 2010 version of the Standard S tandard

Classroom Example Single Zone - 62.1-2007 

High School Classroom 35’ x 35’ (30 people)

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Breathing Zone Outdoor Airflow (V bz) = RpPz + Ra Az

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Occupancy component - 10 cfm/person – 10 x 30 people = 300 cfm

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 Area component component - 0.12 cfm/ft cfm/ft 2 – 0.12 x (35’ x 35’) = 147 cfm Zone Air Distribution Effectiveness

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Zone Outdoor Airflow (Voz) = Vbz/Ez

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Voz = (300 + 147)/1.0 = 447 cfm or 14.9 cfm/person

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Be careful with E z values! Most of the time E z = 0.8 in heating mode which yields a higher  higher ventilation ventilation rate requirement. Reference Table Table 6-2!

Ventilation Rate Procedure

Multiple Zone Recirculating Systems 

Vou = ∑(RpPz + Ra Az) for all zones – Uncorrected Outdoor Air Intake

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Vot = Vou/Ev – Outdoor Air Intake

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To determine the System Ventilation Efficiency (E v), use Table 6-3 with the Zone Primary Outdoor Air Fraction Z p

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Primary Outdoor Air Fraction Z p

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Zp = Voz/Vpz

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Voz – Zone outdoor airflow

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Vpz – Zone primary airflow (for VAV systems V pz is the minimum minimum expected  expected primary airflow for design purposes)

Multiple Zone Example Office 15’x10’ 1 Occupant 100 cfm SA Corridor 4’ wide 0 Occupants 150 cfm SA

Break Room 10’x20’ 4 Occupants 200 cfm SA

Storage 10’x10’ 0 Occupants 50 cfm SA

Conference 12’x12’ 6 Occupants 150 cfm SA

Office 15’x10’ 1 Occupant 100 cfm SA

Office 10’x20’ 2 Occupants 150 cfm SA

Note: supply airflows are heating minimum values Office 18’x10’ 2 Occupants 150 cfm SA

Office 18’x10’ 2 Occupants 150 cfm SA

Multiple Zone Example 

Vou = ∑(RpPz + Ra Az) for all zones – uncorrected outdoor air intake

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Offices

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15’ x 10’ x (0.06 cfm/ft2) + 1 person x 5 cfm/person = 14 cfm OA

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10’ x 20’ x (0.06 cfm/ft2) + 2 people x 5 cfm/person = 22 cfm OA

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18’ x 10’ x (0.06 cfm/ft2) + 2 people x 5 cfm/person = 21 cfm OA

Office total 

(14 cfm) x 2 + 22 cfm + (21 cfm) x 2

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Office total = 92 cfm OA

Multiple Zone Example 

Vou = ∑(RpPz + Ra Az) for all zones – uncorrected outdoor air intake

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Break Room  10’ x 20’ x (0.06 cfm/ft2) + 4 people x 5 cfm/person = 32 cfm OA

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Conference  12’ x 12’ x (0.06 cfm/ft2) + 6 people x 5 cfm/person = 39 cfm OA

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Storage  10’ x 10’ x (0.12 cfm/ft2) = 12 cfm OA

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Corridor  296 ft2 x (0.06 cfm/ft2) = 18 cfm OA

Multiple Zone Example 

Vou = ∑(RpPz + Ra Az) for all zones – uncorrected outdoor air intake

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Office total – 92 cfm

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Break room – 32 cfm

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Conference – 39 cfm

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Storage – 12 cfm

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Corridor -18 cfm

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Building total = 92 + 32 + 39 + 12 + 18 = 194 cfm

… BUT BUT WAIT!

Multiple Zone Example 

Building total = 194 cfm OA

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But Vou is the “uncorrected” outdoor air intake – we also have to account for the System Ventilation Efficiency (Ev)

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What exactly is the System Ventilation Efficiency?

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Here is where it can get a little tricky!

System Ventilation Efficiency 

The System Ventilation Efficiency (E v) increases the outside air at the system to account for the critical zones

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Example  The critical zone is a conference room where the zone requires 50% of the minimum supply air to be outside air  Based on the building area and occupant requirements for ventilation, the % outside air at the air handling unit is only 15% always be  be underventilated under these conditions  The critical zone will always

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 ASHRAE says we need need to increase increase the outside outside air at the unit unit to compensate for this How does this affect our Multiple Zone Example?

Multiple Zone Example 

Lets calculate the Zone Primary Outdoor Air Fraction for each zone

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Zp = Voz/Vpz

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Office 1 – 15’ x 10’ 

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Office 2 – 10’ x 20’ 

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Zp = (18 cfm OA)/(100 cfm SA) = 0.18

Zp = (28 cfm OA)/(150 cfm SA) = 0.19

Office 3 – 18’ x 10’ 

Zp = (27 cfm OA)/(150 cfm SA) = 0.18

Multiple Zone Example 

Zp = Voz/Vpz

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Break Room  Zp = (40 cfm OA)/(200 cfm SA) = 0.20

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Conference  Zp = (49 cfm OA)/(150 cfm SA) = 0.33

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Storage  Zp = (15 cfm OA)/(50 cfm SA) = 0.30

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Corridor  Zp = (23 cfm OA)/(150 cfm SA) = 0.16

Multiple Zone Example 

Office 1 – Z p = 0.18

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Office 2 – Z p = 0.19

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Office 3 – Z p = 0.18

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Break Room - Z p = 0.20

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Conference - Z p = 0.33

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Storage - Z p = 0.30

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Corridor - Zp = 0.16

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Highest Zp – Conference – 0.33

Multiple Zone Example 

Vot = Vou/Ev – Outdoor Air Intake

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Using Table 6-3 with Zp = 0.33 and by interpolating, Ev = 0.82

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Vot = (194 cfm)/0.82

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Vot = 236 cfm OA required

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Will use 240 cfm OA

0.82

Multiple Zone Example 

Now what happens if we increase the VAV VAV box minimums on the critical zones?

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Zp = Voz/Vpz

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Conference (increased minimum SA from 150 cfm to 250 cfm) Zp = (49 cfm OA)/(250 cfm SA) = 0.20 (previously 0.33) 

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Storage (increased minimum SA from 50 cfm to 100 cfm) Zp = (15 cfm OA)/(100 cfm SA) = 0.15 (previously 0.30) 

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Using Table 6-3 with the max Zp = 0.20 and by interpolating, Ev = 0.95

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Vot = (194 cfm)/0.95

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Vot = 205 cfm cf m OA required

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Use 205 cfm OA instead of 240 cfm

0.95

 Alternative Procedures 

 Appendix A calculate System Ventilation Ventilation Efficiency Efficiency (Ev) other   Another way to calculate than using Table 6-3  Ev = minimum (Evz)  Evz = 1 + Xs – Zd Average Outdoor Air Fraction at the air handling unit  Xs is the Average  Zd is the Discharge Outdoor Air Fraction at the zone  In our Multiple Zone Example,  Ev = 1 + (194 cfm)/(1200 cfm) – 0.33 = 1 + 0.16 – 0.33 = 0.83  Vot = (194 cfm)/0.83 = 234 cfm – very similar result   All zone Zp values do not necessarily need to be calculated, just the “critical zones”

Title 24 Requirements 

But what about Title 24?

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Based on Section 121 – Requirements for Ventilation

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Mechanical Ventilation 

The conditioned floor area of the t he space times the applicable ventilation ventilat ion rate from Table Table 121-A or

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15 cfm/person times the expected number of occupants

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Cannot be less than the larger of the two!

Multiple Zone Example 

 Area-based ventilation ventilation rate:  Table 121-A for office space (other) is 0.15 cfm/sf  Required OA = 1,600 sf x 0.15 cfm/sf = 240 cfm

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People-based ventilation rate: People-based  15 cfm/person  Required OA = 18 people x 15 cfm/person = 270 cfm

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Title 24 Ventilation – 270 cfm

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 ASHRAE Standard Standard 62.1 Ventilation Ventilation – 240 cfm This result is not always the case!

Title 24 Requirements 

Section 144 (d) – Space-cond Space-conditioning itioning Zone Controls 

Minimizes reheating to reduce energy use

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The volume of primary air that is reheated, re-cooled, or mixed air supply shall not exceed the larger of:

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50 percent of the peak primary airflow, or

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The design zone outdoor airflow rate per Section 121

May not be possible to increase minimum zone airflows to reduce Zp in the critical zones

Title 24 Requirements 

Section 121 (c) – Operation and Control Requirements 

Required Demand Control Ventilation 

CO2 sensors required in densely occupied spaces (occupant density greater than or equal to 25 people per 1,000 sf)

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May reduce OA for these spaces based on CO2 levels

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Dynamic Reset not a requirement in ASHRAE ASHRAE Standard 62.1

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CO2 sensors are required for LEED OA Delivery Monitoring credit

 ASHRAE 62.1 Design Tips Tips 

Identify the “critical zones” 

High occupant density and low airflow requirement (i.e. little to no envelope load)

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Interior conference/meeting rooms

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Interior waiting/lobby areas

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Interior break rooms

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Not necessarily limited to interior zones (north-facing and no glass)

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Increase VAV box minimum airflows in critical zones to reduce outside air where possible [ watch out for Title 24 Section 144 (d) ]

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May use transfer fans to increase supply air to a critical space

 ASHRAE 62.1 Design Tips Tips 

May account for Occupant Diversity – the ratio of the system population to the sum of the zone populations

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Utilize calculation spreadsheet   

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Spreadsheet provided with ASHRAE 62.1 User’s Manual  Allows you you to input only the critical zones Spreadsheet uses Appendix A approach

Caution! 

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Don’t forget about building pressurization - a pressurization calc should be done to ensure that the building is positively pressurized which could result in higher air quantities than ASHRAE 62.1 requires Make sure heating minimum supply air values can handle the zone heat losses with the selected reheat coil

LEED Compliance 

LEED Version 3.0 requires that the design meet the minimum requirements of Sections 4 through 7 of ASHRAE Standard 62.1-2007  

IEQ Prerequisite 1 – Minimum IAQ Performance (mandatory) IEQ Credit 2 – Increased Ventilation (optional)

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The Ventilation Rate Procedure must be correctly documented and uploaded to LEED Online for review

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Best method – “62MZCalc” spreadsheet    

Pre-programmed spreadsheet template  Accepted by USGBC  Available with purchase of ASHRAE 62.1 User’s Manual Free through LEED Online under “Credit Resources”

LEED Compliance – 62MZCalc Entered Values Critical Zone

System Ev = 0.84 Required Vot = 229 cfm

LEED Compliance – 62MZCalc 

“62MZCalc” spreadsheet tips  

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Required only to input “potentially critical zones”  Analyze all operating conditions 

Cooling mode

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Heating mode

 Apply occupant diversity (D) where possible 

Check with Architect for a building program or design occupancy

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May be based on full-time equivalent (FTE) occupants

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Spreadsheet instructions

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Cell unlock code

LEED Compliance 

LEED Documentation Materials  

IEQp1 Submittal Template (LEED Online form v3.0 or Template PDF v2.2)  ASHRAE Standard 62.1 Documentation Documentation of the VRP 

“62MZCalc” Spreadsheet

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Trane Trace Trace 700 Calculation Report

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Carrier’s HAP Calculation Report

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Other suitable analysis program

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Equipment schedules identifying design OA for all systems

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Equipment submittals (if applicable)

LEED Compliance 

LEED Design Review Process    

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Design Application Submission Design Application Review GBCI (25 business days) Final Design Review  Appeals ($500 per credit)

Design Application Review Pending Issues  “It is unclear…”  Technic echnical al Advice  “Please provide revised VRP calculations demonstrating…” 

Design Application Application Review Comments The LEED Submittal Template Template has been provided stating st ating that the project complies with the minimum requirements of ASHRAE Standards 62.1-2004. A narrative has been provided describing the project's ventilation system design. However, specific information regarding the fresh air intake volumes has not been provided. TECHNICAL ADVICE: Please provide a more detailed narrative or resubmit the t he LEED Submittal Template Template to include a more detailed narrative that includes specific information regarding the fresh air intake volumes.

Design Application Application Review Comments The LEED Submittal Template has been provided stating that the project complies with the minimum requirements of  ASHRAE Standard 62.1-2004, Ventilat ion for Acceptable Indoor Air Quality, using the Ventilat ion Rate Procedure… However, two issues are pending: 1. The documentation and Ventilation Rate Procedure (VRP) calculations indicate an Ez value of 1.0 for all VRP calculations, and it is unclear whether the operating conditions represented in the calculations reflect the worst-case scenario. 2. It is unclear how the System System Ventilation Efficiency (Ev) value has been determined. In addition, it is unclear which zone, zone, for each unit serving multiple zones, is the critical zone. Therefore, it is unclear whether the critical zone has been used to determine the Primary Outdoor Air Fraction (Zp) and System Ventilation Efficiency (Ev) values. TECHNICAL ADVICE: 1. Please provide revised VRP calculations demonstrating that the values have been adjusted such that they are in compliance with ASHRAE Standard 62.1-2004, Table 6.2. Provide a detailed narrative including specific information regarding the selection of the worst-case design conditions for the VRP calculations. Alternatively, include information explaining the selection of an Ez value of 1.0 for all systems. 2. Indicate in the narrative how the Ev value value has been determined, as well as the critical zone for each unit serving multiple zones. If necessary, provide revised calculations demonstrating that the critical zone has been used to determine the Primary Outdoor Air Fraction (Zp) and System Ventilation Efficiency (Ev) values.

Design Application Application Review Comments The LEED Prerequisite P rerequisite Form has been provided stating that the project is mechanically ventilated and mechanically conditioned, therefore the project applies Case 1. T he project has utilized the VRP Compliance Calculator. However, the tenant guidelines do not indicate the requirements of ASHRAE 62.1-2007 must be met and a copy of the legally binding document (e.g. lease, sales agreement), specifying minimum performance criteria for IEQp1 for the tenant work, has not been bee n provided. TECHNICAL ADVICE: 1. Provide revised tenant guidelines guidelines to include a reference to meeting the minimum minimum requirements of ASHRAE 62.12007 and ensure that a copy of the t he legally binding document (e.g. lease, sales agreement), explicitly explicitly stating the performance requirements for the tenant work is included.

Other Important Sections in  ASHRAE 62.1 

Minimum MERV ratings for filters (minimum MERV 6 upstream of cooling coils)

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Exhaust rates (Table 6.4)    

Restrooms Copy/printing rooms Kitchenettes (break rooms) Chemical storage rooms (housekeeping)

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Natural ventilation – specifies location and size of openings in lieu of or in addition to mechanical ventilation

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Outside air intake minimum separation distances (Table 5.1)

References   

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 ASHRAE Standard Standard 62.1 PDFs available of older versions of the Standard  ASHRAE 62.1 62.1 User’s Manual 

More detailed explanation of the Ventilation Rate Procedure

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Example problems

 ASHRAE website website

Questions?