Option 1 should read: "ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda ). Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy."
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Credit language
© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Have in place a system for continuous tracking and optimization of systems that regulate indoor comfort and conditions (air temperature, humidity, air speed and radiant temperature) in occupied spaces. Have a permanent monitoring system to ensure ongoing building performance to the desired comfort criteria as determined by either of the following standards:
Option 1. ASHRAE standard 55-2004 or non-U.S. equivalent
ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda). Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy.Option 2. ISO 7730: 2005 & CEN standard EN 15251: 2007
Projects outside the U.S. may earn this credit by meeting the requirements of International Organization for Standardization (ISO) 7730, 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. The building must establish the following:- Continuous monitoring of, at a minimum, air temperature and humidity in occupied spaces. The sampling interval cannot exceed 15 minutes.
- Periodic testing of air speed and radiant temperature in occupied spaces. Using handheld meters is permitted.
- Alarms for conditions that require system adjustment or repair. Submit a list of the sensors, zone set-points and limit values that would trigger an alarm.
- Procedures that deliver prompt adjustments or repairs in response to problems identified.
Credit substitution available
You may use the LEED v4 version of this credit on v2009 projects. For more information check out this article.What does it cost?
Cost estimates for this credit
On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.
Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.
This information is also available in a full PDF download in The Cost of LEED v4 report.
Learn more about The Cost of LEED v4 »Frequently asked questions
The LEED Reference Guide states that we need to have at least one temperature sensor in each HVAC zone. What defines an HVAC zone for this credit?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 type of measurement instrument do we need to use to monitor radiant temperature in occupied spaces?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.) |
Addenda
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add option title that reads: "OPTION 1. ASHRAE Standard 55-2004 or Non-U.S. Equivalent" after the first paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add option title that reads: "OPTION 2. ISO 7730: 2005 & CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
The second sentence should read: "Have a permanent monitoring system to ensure ongoing building performance to the desired comfort criteria as determined by either of the following standards:"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add the following paragraph: "Projects outside the U.S. may earn this credit by meeting the requirements of International Organization for Standardization (ISO) 7730, 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
5/7/2007
LEED Interpretation
Inquiry:
The project team is providing individual floor air valves each with variable duration (open / close) primary air dampers and multi-position diffusers for occupant comfort conditioning as part of an under floor air distribution system. Individual floor air valves will be provided for a minimum of 50% of the building occupants. The variable duration (open/close) primary air dampers in the floor air valves will be controlled using thermostats. Multiple air valves will be connected to one thermostat, such that there will not be one thermostat for 50% of the occupants. However, all of the local floor air valves include multi-position adjustable floor diffusers which are integral to each floor air valve. At a minimum, 50% of the occupants will have control over the primary air flow direction out of the local floor air valve in their space (comfort zone) by adjusting the multi-position local floor diffuser air outlet. Changing the direction of the air flow inherently changes the speed of the airflow in a given direction. LEED NC v.2.2, First Edition, Reference Guide, p361, indicates: Conditions for Thermal Comfort per ASHRAE Standard 55-2004 include the following as primary factors: air temperature, radiant temperature, air speed, and humidity. The Reference guide also states that, "Comfort System control, for the purposes of this credit, is defined as the provision of control over at least one of these primary factors in the occupant\'s local environment" and that "Individual adjustments may involve individual thermostat controls, local diffusers at floor, desk or overhead levels, or control of individual radiant panels, and energy system design." This CIR is to confirm that providing air valves, with multi position diffusers, that allow more than 50% of the occupants to change the direction of airflow out of their floor diffuser (which changes the speed in that direction) will satisfy the LEED credit requirement for thermal comfort.
Ruling:
The applicant is asking whether multi position diffusers that allow changes in direction of airflow satisfy the requirements for individual comfort control for EQc6.2. The applicant is suggesting that changing the direction of airflow inherently changes the speed of the airflow in a given direction, meeting credit compliance by providing control of air speed. Simply changing the direction of airflow in one\'s workspace does not adequately meet the credit intent to provide individual comfort controls. Individual diffusers must have the ability to regulate the speed of the air leaving the diffuser, not simply the direction of airflow. Applicable Internationally.
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
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© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Have in place a system for continuous tracking and optimization of systems that regulate indoor comfort and conditions (air temperature, humidity, air speed and radiant temperature) in occupied spaces. Have a permanent monitoring system to ensure ongoing building performance to the desired comfort criteria as determined by either of the following standards:
Option 1. ASHRAE standard 55-2004 or non-U.S. equivalent
ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda). Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy.Option 2. ISO 7730: 2005 & CEN standard EN 15251: 2007
Projects outside the U.S. may earn this credit by meeting the requirements of International Organization for Standardization (ISO) 7730, 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. The building must establish the following:- Continuous monitoring of, at a minimum, air temperature and humidity in occupied spaces. The sampling interval cannot exceed 15 minutes.
- Periodic testing of air speed and radiant temperature in occupied spaces. Using handheld meters is permitted.
- Alarms for conditions that require system adjustment or repair. Submit a list of the sensors, zone set-points and limit values that would trigger an alarm.
- Procedures that deliver prompt adjustments or repairs in response to problems identified.
Credit substitution available
You may use the LEED v4 version of this credit on v2009 projects. For more information check out this article.XX%
Upgrade to LEEDuser Premium to see how many projects achieved this credit. Try it free »
Got the gist of IEQc2.3 but not sure how to actually achieve it? LEEDuser gives step-by-step help. Premium members get:
- Checklists covering all the key action steps you'll need to earn the credit.
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- On-the-fly suggestions of useful items from the Documentation Toolkit and Credit Language.
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- Sample templates to help guide your narratives and LEED Online submissions.
- Examples of actual submissions from certified LEED projects.
The LEED Reference Guide states that we need to have at least one temperature sensor in each HVAC zone. What defines an HVAC zone for this credit?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 type of measurement instrument do we need to use to monitor radiant temperature in occupied spaces?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.) |
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Option 1 should read: "ASHRAE Standard 55-2004, Thermal Comfort Conditions for Human Occupancy (with errata but without addenda ). Projects outside the U.S. may use a local equivalent to ASHRAE Standard 55-2004 Thermal Comfort Conditions for Human Occupancy."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add option title that reads: "OPTION 1. ASHRAE Standard 55-2004 or Non-U.S. Equivalent" after the first paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add option title that reads: "OPTION 2. ISO 7730: 2005 & CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 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
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
The second sentence should read: "Have a permanent monitoring system to ensure ongoing building performance to the desired comfort criteria as determined by either of the following standards:"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add the following paragraph: "Projects outside the U.S. may earn this credit by meeting the requirements of International Organization for Standardization (ISO) 7730, 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
5/7/2007
LEED Interpretation
Inquiry:
The project team is providing individual floor air valves each with variable duration (open / close) primary air dampers and multi-position diffusers for occupant comfort conditioning as part of an under floor air distribution system. Individual floor air valves will be provided for a minimum of 50% of the building occupants. The variable duration (open/close) primary air dampers in the floor air valves will be controlled using thermostats. Multiple air valves will be connected to one thermostat, such that there will not be one thermostat for 50% of the occupants. However, all of the local floor air valves include multi-position adjustable floor diffusers which are integral to each floor air valve. At a minimum, 50% of the occupants will have control over the primary air flow direction out of the local floor air valve in their space (comfort zone) by adjusting the multi-position local floor diffuser air outlet. Changing the direction of the air flow inherently changes the speed of the airflow in a given direction. LEED NC v.2.2, First Edition, Reference Guide, p361, indicates: Conditions for Thermal Comfort per ASHRAE Standard 55-2004 include the following as primary factors: air temperature, radiant temperature, air speed, and humidity. The Reference guide also states that, "Comfort System control, for the purposes of this credit, is defined as the provision of control over at least one of these primary factors in the occupant\'s local environment" and that "Individual adjustments may involve individual thermostat controls, local diffusers at floor, desk or overhead levels, or control of individual radiant panels, and energy system design." This CIR is to confirm that providing air valves, with multi position diffusers, that allow more than 50% of the occupants to change the direction of airflow out of their floor diffuser (which changes the speed in that direction) will satisfy the LEED credit requirement for thermal comfort.
Ruling:
The applicant is asking whether multi position diffusers that allow changes in direction of airflow satisfy the requirements for individual comfort control for EQc6.2. The applicant is suggesting that changing the direction of airflow inherently changes the speed of the airflow in a given direction, meeting credit compliance by providing control of air speed. Simply changing the direction of airflow in one\'s workspace does not adequately meet the credit intent to provide individual comfort controls. Individual diffusers must have the ability to regulate the speed of the air leaving the diffuser, not simply the direction of airflow. Applicable Internationally.
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
Jason Franken
Sustainability Professional
