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LEED v2009
Core & Shell
Indoor Environmental Quality
Thermal Comfort—Design

LEED CREDIT

CS-2009 IEQc7: Thermal comfort - design 1 point

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© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Design heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of one of the options below:The core and shell base building mechanical system must allow for the tenant build-out to meet the requirements of this credit. See Appendix 1 — Default Occupancy Counts for occupancy count requirements and guidance. Project teams that design their project for mechanical ventilation that do not purchase or install the mechanical system are not eligible achieve this credit.

Option 1. ASHRAE standard 55-2004 or non-U.S. equivalent
Meet the requirements of ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda1). Demonstrate design compliance in accordance with the Section 6.1.1 documentation. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy Section 6.1.1. [India ACP: Thermal Comfort]
Option 2. ISO 7730: 2005 & CEN standard EN 15251: 2007
Projects outside the U.S. may earn this credit by designing heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of International Organization for Standardization (ISO) 7730: 2005 Ergonomics of the thermal environment, Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria; and CEN Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics.

1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

See all forum discussions about this credit »

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Frequently asked questions

ASHRAE-55 comfort criteria ask for space air speed. Is this the same as the supply air volume measured in cubic feet per minute (CFM)?

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What should I do about a warehouse space?

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How can thermal conditions for areas with metabolic rates outside of 1.0–1.3 be determined? (Per ASHRAE Standard 55-2004 Section 5.2.1.1, Figure 5.2.1.1 can be used for areas with metabolic rates between 1.0 and 1.3).

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There are a few spaces in my project that can’t meet these requirements. Can’t I just exclude them?

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See all forum discussions about this credit »

Addenda

7/1/2015Updated: 3/29/2018
Regional ACP
Description of change:
Append to first paragraph the following:

"Or the National Building Code of India 2005 (NBC 2005)"
After first paragraph add the following: "Projects in India may meet the desired comfort criteria specified in the following as a local equivalent to ASHRAE 55-2004:
  • For mechanically conditioned buildings, NBC 2005 Part 8, Section 3 - Table 2

  • For naturally conditioned buildings, NBC 2005 Part 8, Section 1 - Table 9"
Campus Applicable
Yes
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 1 should read: "Meet the requirements of ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy (with errata but without addenda37). Demonstrate design compliance in accordance with the Section 6.1.1 documentation. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy Section 6.1.1."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
The first sentence should read: "Design heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of one of the options below."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 2 should read: "Projects outside the U.S. may earn this credit by designing heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of International Organization for Standardization (ISO) 7730: 2005 Ergonomics of the thermal environment, Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria; and CEN Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new option title that reads: "OPTION 2. ISO 7730: 2005 & CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for occupied spaces, "Occupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new option title that reads: "OPTION 1. ASHRAE Standard 55-2004 or Non-U.S. Equivalent"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S.
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the paragraph, add the addition text "For residential projects, the occupants have a higher level of control over the building systems and are therefore not eligible for this credit."
Campus Applicable
No
Internationally Applicable:
No
9/23/2008
LEED Interpretation
Inquiry:

EQc10 requires compliance with EQc7.1 "Thermal Comfort, Design". ASHRAE 55 uses absolute humidity as the upper moisture limit. EQc10 requires a 60% RH which cuts the ASHRAE 55 absolute humidity in half, or more depending on how cold it gets inside a room when the systems are turned off. If natural ventilation is used at all, and any windows are left partially opened at night, there would be no way to control the humidity to a 60% RH. It is problematic to maintaining a humidity level below 60% when the spaces are unoccupied. The only way to pull humidity out of the space is to run the air conditioning equipment to create condensation, which is itself a potential moisture problem, or to run conditioning systems in heating mode, and so in order to achieve the required humidity levels during unoccupied periods is to potentially run the air conditioning equipment 24 hours a day, seven days a week controlled by a humidistat in the space. There is an apparent flaw in this LEEDS for Schools credit as to comply with this credit the District would need to use up energy and pay higher utility bills during long periods, such as the summer, when the campus is not in use. The USGBC is targeting reducing the carbon footprint of buildings, and the 60% relative humidity requirement is inconsistent with that objective. We suggest some possible alternative mold control techniques during construction of the building instead of conditioning for 60% relative humidity such as: 1. Install mold resistant gypsum board 2. Install weather barrier under exterior finish materials and slab on grade 3. Capillary breaks for footings 4. Provide special inspection for openings and penetrations in the building envelope

Ruling:

The project is proposing alternative mold control techniques that would be employed during construction of the building, in lieu of the stated credit requirement of providing HVAC systems and controls designed to limit space relative humidity to 60% or less during all load conditions, both occupied or unoccupied. While the measures cited are commendable and will reduce the likelihood of moisture penetration, they do not however provide sufficient direct impact on the relative humidity levels in the building after construction and during occupancy. As the humidity levels will not be actively controlled during the operation of the building, the potential will remain for mold to grow if humid conditions occur or perpetuate. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2013
LEED Interpretation
Inquiry:

Can spaces that fall outside of the scope of ASHRAE 55-2004, because the physical activity levels result in a time-averaged MET above 2.0 (such as gymnasiums or fitness centers), be excluded from the credit requirements? Also, can spaces that are not normally comfort conditioned (such as warehouse spaces, apparatus bays, vehicle repair facilities, commercial kitchens) be excluded from the credit requirements?

Ruling:

**Updated October 1, 2013 to clarify the ruling.
No, spaces with a time-averaged metabolic rate above 2.0 MET must meet the requirements for IEQc7.1 Thermal Comfort—Design/IEQc2.3 Occupant Comfort—Thermal Comfort Monitoring. For these unique spaces, an alternative to the requirements of ASHRAE 55-2004 is acceptable provided the project determines acceptable thermal comfort conditions that meet the intent of the credit, and demonstrates that those conditions will be met. Time-weighted average metabolic rates should be determined based on guidance in ASHRAE 55-2004, Normative Appendix A. Most spaces with MET levels above 2.0 would need to meet the cooling / humidity temperature set points for spaces with MET levels of 2.0 in order to meet the intent of the credit. Exceptions will be considered on a case-by-case basis and must include an explanation that justifies how the intent of the credit is met. Kitchens may pursue this option.

Spaces that are not normally comfort conditioned can only be excluded if they are non-regularly occupied. For regularly occupied spaces that are not normally comfort conditioned, and not able to meet the ASHRAE 55 thermal comfort conditions, the project team must include one or more of the following design alternatives: radiant flooring; circulating fans; passive systems, such as nighttime air, heat venting, or wind flow; localized active cooling (refrigerant or evaporative-based systems) or heating systems; or localized, hard-wired fans that provide air movement for occupants’ comfort.

Campus Applicable
No
Internationally Applicable:
Yes
See all forum discussions about this credit »

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Credit achievement rate

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USGBC logo

© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Design heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of one of the options below:The core and shell base building mechanical system must allow for the tenant build-out to meet the requirements of this credit. See Appendix 1 — Default Occupancy Counts for occupancy count requirements and guidance. Project teams that design their project for mechanical ventilation that do not purchase or install the mechanical system are not eligible achieve this credit.

Option 1. ASHRAE standard 55-2004 or non-U.S. equivalent
Meet the requirements of ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda1). Demonstrate design compliance in accordance with the Section 6.1.1 documentation. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy Section 6.1.1. [India ACP: Thermal Comfort]
Option 2. ISO 7730: 2005 & CEN standard EN 15251: 2007
Projects outside the U.S. may earn this credit by designing heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of International Organization for Standardization (ISO) 7730: 2005 Ergonomics of the thermal environment, Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria; and CEN Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics.

1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

XX%

Upgrade to LEEDuser Premium to see how many projects achieved this credit. Try it free »

Got the gist of IEQc7 but not sure how to actually achieve it? LEEDuser gives step-by-step help. Premium members get:

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  • Tracking spreadsheets for materials purchases.
  • Spreadsheets and forms to give to subs and other team members.
  • Guidance documents on arcane LEED issues.
  • Sample templates to help guide your narratives and LEED Online submissions.
  • Examples of actual submissions from certified LEED projects.

ASHRAE-55 comfort criteria ask for space air speed. Is this the same as the supply air volume measured in cubic feet per minute (CFM)?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)


What should I do about a warehouse space?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

How can thermal conditions for areas with metabolic rates outside of 1.0–1.3 be determined? (Per ASHRAE Standard 55-2004 Section 5.2.1.1, Figure 5.2.1.1 can be used for areas with metabolic rates between 1.0 and 1.3).

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

There are a few spaces in my project that can’t meet these requirements. Can’t I just exclude them?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

7/1/2015Updated: 3/29/2018
Regional ACP
Description of change:
Append to first paragraph the following:

"Or the National Building Code of India 2005 (NBC 2005)"
After first paragraph add the following: "Projects in India may meet the desired comfort criteria specified in the following as a local equivalent to ASHRAE 55-2004:
  • For mechanically conditioned buildings, NBC 2005 Part 8, Section 3 - Table 2

  • For naturally conditioned buildings, NBC 2005 Part 8, Section 1 - Table 9"
Campus Applicable
Yes
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 1 should read: "Meet the requirements of ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy (with errata but without addenda37). Demonstrate design compliance in accordance with the Section 6.1.1 documentation. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy Section 6.1.1."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
The first sentence should read: "Design heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of one of the options below."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 2 should read: "Projects outside the U.S. may earn this credit by designing heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of International Organization for Standardization (ISO) 7730: 2005 Ergonomics of the thermal environment, Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria; and CEN Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new option title that reads: "OPTION 2. ISO 7730: 2005 & CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for occupied spaces, "Occupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new option title that reads: "OPTION 1. ASHRAE Standard 55-2004 or Non-U.S. Equivalent"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S.
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the paragraph, add the addition text "For residential projects, the occupants have a higher level of control over the building systems and are therefore not eligible for this credit."
Campus Applicable
No
Internationally Applicable:
No
9/23/2008
LEED Interpretation
Inquiry:

EQc10 requires compliance with EQc7.1 "Thermal Comfort, Design". ASHRAE 55 uses absolute humidity as the upper moisture limit. EQc10 requires a 60% RH which cuts the ASHRAE 55 absolute humidity in half, or more depending on how cold it gets inside a room when the systems are turned off. If natural ventilation is used at all, and any windows are left partially opened at night, there would be no way to control the humidity to a 60% RH. It is problematic to maintaining a humidity level below 60% when the spaces are unoccupied. The only way to pull humidity out of the space is to run the air conditioning equipment to create condensation, which is itself a potential moisture problem, or to run conditioning systems in heating mode, and so in order to achieve the required humidity levels during unoccupied periods is to potentially run the air conditioning equipment 24 hours a day, seven days a week controlled by a humidistat in the space. There is an apparent flaw in this LEEDS for Schools credit as to comply with this credit the District would need to use up energy and pay higher utility bills during long periods, such as the summer, when the campus is not in use. The USGBC is targeting reducing the carbon footprint of buildings, and the 60% relative humidity requirement is inconsistent with that objective. We suggest some possible alternative mold control techniques during construction of the building instead of conditioning for 60% relative humidity such as: 1. Install mold resistant gypsum board 2. Install weather barrier under exterior finish materials and slab on grade 3. Capillary breaks for footings 4. Provide special inspection for openings and penetrations in the building envelope

Ruling:

The project is proposing alternative mold control techniques that would be employed during construction of the building, in lieu of the stated credit requirement of providing HVAC systems and controls designed to limit space relative humidity to 60% or less during all load conditions, both occupied or unoccupied. While the measures cited are commendable and will reduce the likelihood of moisture penetration, they do not however provide sufficient direct impact on the relative humidity levels in the building after construction and during occupancy. As the humidity levels will not be actively controlled during the operation of the building, the potential will remain for mold to grow if humid conditions occur or perpetuate. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2013
LEED Interpretation
Inquiry:

Can spaces that fall outside of the scope of ASHRAE 55-2004, because the physical activity levels result in a time-averaged MET above 2.0 (such as gymnasiums or fitness centers), be excluded from the credit requirements? Also, can spaces that are not normally comfort conditioned (such as warehouse spaces, apparatus bays, vehicle repair facilities, commercial kitchens) be excluded from the credit requirements?

Ruling:

**Updated October 1, 2013 to clarify the ruling.
No, spaces with a time-averaged metabolic rate above 2.0 MET must meet the requirements for IEQc7.1 Thermal Comfort—Design/IEQc2.3 Occupant Comfort—Thermal Comfort Monitoring. For these unique spaces, an alternative to the requirements of ASHRAE 55-2004 is acceptable provided the project determines acceptable thermal comfort conditions that meet the intent of the credit, and demonstrates that those conditions will be met. Time-weighted average metabolic rates should be determined based on guidance in ASHRAE 55-2004, Normative Appendix A. Most spaces with MET levels above 2.0 would need to meet the cooling / humidity temperature set points for spaces with MET levels of 2.0 in order to meet the intent of the credit. Exceptions will be considered on a case-by-case basis and must include an explanation that justifies how the intent of the credit is met. Kitchens may pursue this option.

Spaces that are not normally comfort conditioned can only be excluded if they are non-regularly occupied. For regularly occupied spaces that are not normally comfort conditioned, and not able to meet the ASHRAE 55 thermal comfort conditions, the project team must include one or more of the following design alternatives: radiant flooring; circulating fans; passive systems, such as nighttime air, heat venting, or wind flow; localized active cooling (refrigerant or evaporative-based systems) or heating systems; or localized, hard-wired fans that provide air movement for occupants’ comfort.

Campus Applicable
No
Internationally Applicable:
Yes
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