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LEED v2009
New Construction
Indoor Environmental Quality
Thermal Comfort—Verification

LEED CREDIT

NC-2009 IEQc7.2: Thermal comfort - verification 1 point

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Green Bridge Consulting
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Credit language

USGBC logo

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

Requirements

Achieve IEQ Credit 7.1: Thermal Comfort—Design

Provide a permanent monitoring system to ensure that building performance meets the desired comfort criteria as determined by IEQ Credit 7.1: Thermal Comfort—Design.

Agree to conduct a thermal comfort survey of building occupants within 6 to 18 months after occupancy. This survey should collect anonymous responses about thermal comfort in the building, including an assessment of overall satisfaction with thermal performance and identification of thermal comfort-related problems. Agree to develop a plan for corrective action if the survey results indicate that more than 20% of occupants are dissatisfied with thermal comfort in the building. This plan should include measurement of relevant environmental variables in problem areas in accordance with the standard used for design in IEQ Credit 7.1: Thermal Comfort—Design.

Residential projects are not eligible for this credit.

See all forum discussions about this credit »

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Frequently asked questions

Where did the 7-point scale requirement come from? We have had our documentation questioned in reviews because we did not use this scale.

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Addenda

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
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
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:
In the last sentence of the first paragraph, replace "ASHRAE Standard 55-2004 (with errata but without addenda)" with "the standard used for design in IEQ Credit 7.1: Thermal Comfort - Design."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

The project is an 80,000 sf K-12 school located in the pacific northwest. A majority of the building is being conditioned by "standard" mechanical means and can demonstrate compliance according to ASHRAE 55-2004 Figure 5.2.1.1., however there are portions of the building that will be thermally regulated by natural ventilation and with extensive radiant systems.The purpose of this request is to determine whether the more passive, naturally ventilated portion of the building may be considered "naturally conditioned" with their thermal comfort criteria evaluated according to ASHRAE 55-2004 Figure 5.3 rather than being evaluated according to Figure 5.2.1.1.The northwest climate is considered heating dominated with narrow diurnal temperature variations and as a consequence has limited cooling needs, especially during the school year. The need for cooling is isolated to only brief time periods at the beginning and end of the 9-month school year when potential thermal comfort concerns would arise. To mitigate thermal comfort concerns during these isolated times, the design incorporates occupant-controlled operable windows and ceiling fans to allow comfort control within the classrooms. In addition to the operable windows, the design also includes utilizing the thermal massing properties of the concrete floors to better modulate the release of cooling within the space(s). The cooling will be supplied by evaporatively-cooled water via hydronic loops in the floors during the nighttime periods when the building is unoccupied. The intent is pre-charge the thermal mass of the floors with enough cooling to offset the effects of internal heat gains and eliminate the need for active mechanical cooling during the day. Since the charging is taking place during the evenings, there will not be any ability for the occupants to directly call for additional cooling to be added to floor or space and the mass will in essence be allowed to release it cooling naturally trough out the day. Lastly, we are interpreting that this approach of pre-cooling the mass without the need of compressor-based mechanical cooling could be construed as a assisted passive approach, however it is unclear whether the USGBC will recognize these spaces as "naturally conditioned" for the purposes of IEQc7.1. ASHRAE 55-2004, Section 5.3, states that "occupant-controlled naturally conditioned spaces are those spaces where the thermal conditions of the space are regulated primarily by the occupants through opening and closing of windows". We believe that the definition is still being satisfied with the mass pre-charging strategy described previously, since the regulation of the thermal conditions will still be controlled by the occupants through the opening and closing of windows.Can the thermal comfort criteria in these rooms be evaluated according to "naturally conditioned" rather than "typical" criteria and if so, is modeling an acceptable means of documenting compliance?

Ruling:

The applicant is asking whether a space that meets the ASHRAE Standard 55-2004 definition of "naturally conditioned spaces, occupant controlled," but is also served by an in-floor radiant cooling system that is in turn served by an evaporatively-cooled water tower that will be utilized at night to pre-charge the high thermal mass concrete floors, may be evaluated according to ASHRAE Standard 55-2004 Section 5.3 - Optional Method for Determining Acceptable Thermal Conditions in Naturally Conditioned Spaces in lieu of the requirements of Section 5.2 Method for Determining Acceptable Thermal Conditions in Occupied Spaces.Section 5.3 of Standard 55-2004 states, "there must be no mechanical cooling system for the space (e.g. refrigerated air cooling, radiant cooling, or desiccant cooling.)" in order to use the Optional Method for Determining Acceptable Thermal Conditions in Naturally Conditioned Spaces. If the radiant cooling system is operated during the day, the project would be considered mechanically cooled and not eligible to use the Section 5.3 method. However, if the system is operated as described in the Interpretation Request and the radiant cooling system is only used at night as a pre-cooling strategy then the intent and spirit of the conditions for using Section 5.3 are met. Note that:1. For times when active mechanical cooling OR heating is used during occupied hours, Section 5.3 does not apply and Section 5.2 Method for Determining Acceptable Thermal Conditions in Occupied Spaces shall be used.2. In the Cooling season when the night-time pre-cooling strategy is used, the minimum design operative temperatures in the morning shall be evaluated compared to the allowable minimum operative temperature based on Section 5.3 to ensure comfortable conditions throughout the day. Applicable internationally.

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

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Credit achievement rate

XX%

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

LEEDuser expert

April Brown

Green Bridge Consulting
Sustainable Building Consultant

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USGBC logo

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

Requirements

Achieve IEQ Credit 7.1: Thermal Comfort—Design

Provide a permanent monitoring system to ensure that building performance meets the desired comfort criteria as determined by IEQ Credit 7.1: Thermal Comfort—Design.

Agree to conduct a thermal comfort survey of building occupants within 6 to 18 months after occupancy. This survey should collect anonymous responses about thermal comfort in the building, including an assessment of overall satisfaction with thermal performance and identification of thermal comfort-related problems. Agree to develop a plan for corrective action if the survey results indicate that more than 20% of occupants are dissatisfied with thermal comfort in the building. This plan should include measurement of relevant environmental variables in problem areas in accordance with the standard used for design in IEQ Credit 7.1: Thermal Comfort—Design.

Residential projects are not eligible for this credit.

XX%

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

Got the gist of IEQc7.2 but not sure how to actually achieve it? LEEDuser gives step-by-step help. Premium members get:

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Where did the 7-point scale requirement come from? We have had our documentation questioned in reviews because we did not use this scale.

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.)

7/19/2010Updated: 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
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
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:
In the last sentence of the first paragraph, replace "ASHRAE Standard 55-2004 (with errata but without addenda)" with "the standard used for design in IEQ Credit 7.1: Thermal Comfort - Design."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

The project is an 80,000 sf K-12 school located in the pacific northwest. A majority of the building is being conditioned by "standard" mechanical means and can demonstrate compliance according to ASHRAE 55-2004 Figure 5.2.1.1., however there are portions of the building that will be thermally regulated by natural ventilation and with extensive radiant systems.The purpose of this request is to determine whether the more passive, naturally ventilated portion of the building may be considered "naturally conditioned" with their thermal comfort criteria evaluated according to ASHRAE 55-2004 Figure 5.3 rather than being evaluated according to Figure 5.2.1.1.The northwest climate is considered heating dominated with narrow diurnal temperature variations and as a consequence has limited cooling needs, especially during the school year. The need for cooling is isolated to only brief time periods at the beginning and end of the 9-month school year when potential thermal comfort concerns would arise. To mitigate thermal comfort concerns during these isolated times, the design incorporates occupant-controlled operable windows and ceiling fans to allow comfort control within the classrooms. In addition to the operable windows, the design also includes utilizing the thermal massing properties of the concrete floors to better modulate the release of cooling within the space(s). The cooling will be supplied by evaporatively-cooled water via hydronic loops in the floors during the nighttime periods when the building is unoccupied. The intent is pre-charge the thermal mass of the floors with enough cooling to offset the effects of internal heat gains and eliminate the need for active mechanical cooling during the day. Since the charging is taking place during the evenings, there will not be any ability for the occupants to directly call for additional cooling to be added to floor or space and the mass will in essence be allowed to release it cooling naturally trough out the day. Lastly, we are interpreting that this approach of pre-cooling the mass without the need of compressor-based mechanical cooling could be construed as a assisted passive approach, however it is unclear whether the USGBC will recognize these spaces as "naturally conditioned" for the purposes of IEQc7.1. ASHRAE 55-2004, Section 5.3, states that "occupant-controlled naturally conditioned spaces are those spaces where the thermal conditions of the space are regulated primarily by the occupants through opening and closing of windows". We believe that the definition is still being satisfied with the mass pre-charging strategy described previously, since the regulation of the thermal conditions will still be controlled by the occupants through the opening and closing of windows.Can the thermal comfort criteria in these rooms be evaluated according to "naturally conditioned" rather than "typical" criteria and if so, is modeling an acceptable means of documenting compliance?

Ruling:

The applicant is asking whether a space that meets the ASHRAE Standard 55-2004 definition of "naturally conditioned spaces, occupant controlled," but is also served by an in-floor radiant cooling system that is in turn served by an evaporatively-cooled water tower that will be utilized at night to pre-charge the high thermal mass concrete floors, may be evaluated according to ASHRAE Standard 55-2004 Section 5.3 - Optional Method for Determining Acceptable Thermal Conditions in Naturally Conditioned Spaces in lieu of the requirements of Section 5.2 Method for Determining Acceptable Thermal Conditions in Occupied Spaces.Section 5.3 of Standard 55-2004 states, "there must be no mechanical cooling system for the space (e.g. refrigerated air cooling, radiant cooling, or desiccant cooling.)" in order to use the Optional Method for Determining Acceptable Thermal Conditions in Naturally Conditioned Spaces. If the radiant cooling system is operated during the day, the project would be considered mechanically cooled and not eligible to use the Section 5.3 method. However, if the system is operated as described in the Interpretation Request and the radiant cooling system is only used at night as a pre-cooling strategy then the intent and spirit of the conditions for using Section 5.3 are met. Note that:1. For times when active mechanical cooling OR heating is used during occupied hours, Section 5.3 does not apply and Section 5.2 Method for Determining Acceptable Thermal Conditions in Occupied Spaces shall be used.2. In the Cooling season when the night-time pre-cooling strategy is used, the minimum design operative temperatures in the morning shall be evaluated compared to the allowable minimum operative temperature based on Section 5.3 to ensure comfortable conditions throughout the day. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes

LEEDuser expert

April Brown

Green Bridge Consulting
Sustainable Building Consultant

See all LEEDuser forum discussions about this credit » Unsubscribe from discussions about NC-2009 IEQc7.2