IEQc7.1 requires that HVAC designs meet the requirements of ASHRAE Standard 55-2004, which deals with thermal comfort of building occupants. Specifically, ASHRAE 55 requires project teams to address air temperature, radiant temperature, humidity, and air speed. Earning this credit also sets the stage for you to earn IEQc7.2: Thermal Comfort—Verification.
In most cases, designing a system that complies with ASHRAE-55 is standard practice and documentation is the only LEED-specific requirement for achieving the credit, so it should cost very little to earn.
Meeting this credit in naturally ventilated spaces is tricky, because it’s hard to ensure that thermal conditions remain within the requisite range. It’s really only possible in a few specific climatic regions with especially temperate conditions.
Certain spaces, such as greenhouses, gymnasiums, warehouses or manufacturing facilities often operate outside of the ranges defined by ASHRAE-55, which can put the project in conflict with designing either mechanical and passive systems that meet the credit requirements. If you have these spaces in your project, check with GBCI on whether you can earn the credit through an alternative compliance path.
Regardless of the project type, considering target thermal comfort conditions—and designing to meet those conditions—early in the process is very helpful.
While the credit requirements, and the referenced ASHRAE standard, have not changed from older versions of LEED, the documentation requirements for the credit are now more stringent. Completing the new LEED Online credit form requires greater attention to detail and more supporting calculations, which set a higher bar for coordination among team members.
Supply air volume (CFM) is different from linear air speed measured in feet per minute (FPM). Linear air speed in FPM is relevant to comfort requirements. This information can be derived from the diffuser throw value.
You can establish compliance based on an alternative method to ASHRAE 55.
For spaces with a time-averaged metabolic rate above 2.0 MET, the project must determine acceptable thermal comfort conditions that meet the intent of the credit, and demonstrate that those conditions will be met. See LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #10279 for more details.
For spaces such as warehouses that are not normally conditioned for comfort, the project team may 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. Again, see LI #10279 for more details.
The mechanical engineer and architect review ASHRAE-55 along with the credit requirements in the context of the project. ASHRAE-55 requires that you establish a comfort zone based on several variables that affect occupant comfort, and design mechanical systems to create thermal conditions within the comfort zone in each occupied space. Comfort zone calculations are based on the following variables:
Identify any unique programming or climate conditions that might make it tricky to get the credit. Fitness rooms, gyms, natatoriums, or very humid climates often create conditions that require special consideration.
Consider whether mechanical or natural ventilation will be used. When considering natural ventilation systems, review ASHRAE-55 section 5.3 for a description of the relevant requirements.
Include credit requirements in the Owner's Project Requirements for the commissioning credits EAp1 and EAc3.
Consider design implications of credit requirements early in program development. For example, if you are in a humid climate you may need additional dehumidification, which will affect your mechanical space requirements.
Consider how credit requirements will affect energy use and occupant experience, and whether programming is consistent with this credit. This credit is particularly worthwhile for any indoor environment in which occupant productivity is of key importance, and where occupants will benefit from optimized indoor thermal conditions.
Consider pursuing IEQc7.2: Thermal Comfort—Verification in combination with this credit. IEQc7.2 requires an occupant comfort survey after occupancy.
In order to achieve IEQc7.2, you have to achieve IEQc7.1, and you will have to install a permanent monitoring system to provide ongoing feedback about thermal conditions. If you are only pursuing IEQc7.1, there is no requirement for a permanent monitoring system. Residential projects cannot earn IEQc7.2.
This credit is generally a low- or no-cost credit. When it does add significant costs, that’s usually because it wasn’t considered early enough, so more equipment has to be added to provide, for example, additional dehumidification. An added cost like that could be prevented by designing the right system early in the schematic design.
In climates where either heating or cooling predominate, or in very humid climates, meeting ASHRAE-55 year-round might require additional system components. For example, spaces that may not otherwise be cooled—like gymnasiums—may need dehumidification or cooling systems to meet the ASHRAE-55 comfort criteria year-round.
It is always important to consider building orientation, the heat-island effect, insulation levels and other design considerations that will have a direct effect on thermal conditions and on the energy consumed to achieve those conditions, but these are not variables that are used as inputs for establishing a thermal comfort zone in ASHRAE-55, so they don’t directly affect whether or not you achieve this credit.
Review how building systems might contribute to or hinder achievement of this credit and review site-specific conditions that will affect building conditioning.
Determine which HVAC system types (mechanical, mixed mode, or natural) and system components can best meet the credit requirements and review any special programming requirements for ventilation, humidity and thermal conditions. For example, consider whether in-floor radiant heating is preferable to forced-air systems and which are best suited to a project’s programming and budget, and confirm that the system will be capable of operating within the established comfort zone.
When beginning to consider thermal conditioning systems, review which system types will not only meet credit requirements, but will balance performance, efficiency and cost while creating an optimal thermal environment in the given climatic region. In some regions, direct evaporative cooling may be an appropriate option, while in others dehumidification may be needed to meet the credit requirements. Review the feasibility of natural ventilation systems versus mechanical systems and consider their effect on energy use, programming, and credit achievement.
Review ASHRAE-55 section 6.1.1 to understand the credit documentation requirements. Assess these inputs:
Review how thermal controls and operable windows affect credit requirements. Projects in very temperate climates may meet the credit requirements through the use of operable windows exclusively, as long as mean monthly outdoor temperatures are between 50°F–92°F. See ASHRAE-55 section 5.3 for details.
Include credit-related information in the Basis of Design for the commissioning credits EAp1 and EAc3. At a minimum this should include:
Don’t assume that projects in Southwestern or other dry climates will automatically meet the humidity requirements of ASHRAE-55. These climates may have a significant number of days in which operating conditions will exceed the ASHRAE-55 requirements for humidity. Refer to the National Climatic Data Center for regional weather data (see Resources).
Natural ventilation designs are more significantly affected by climate and weather than mechanical systems. Although the methodology and inputs for documenting compliance are the same as for mechanical systems, in certain regions project teams using passive systems may have difficulty meeting ASHRAE-55 due to program constraints or seasonal temperatures that are outside of the prescribed range of 50°F–92°F.
Provide occupant controls for each individual space and avoid trying to normalize conditions in large areas or zones of a building. Separate controls will make it easier to achieve the credit in all spaces and improve occupant comfort while reducing unneeded energy use. For example, if there are ten adjacent offices, provide controls for each office separately. This strategy can also help you earn IEQc6.2: Controllability of Systems—Thermal Comfort. Added controls may increase upfront costs, but reduced energy consumption should help offset those costs.
Examine operating conditions to confirm how likely you are to meet the credit requirements.
Pick the best calculation method for demonstrating credit achievement. Document IEQc7.1 using a Predicted Mean Vote/Predicted Percentage of Dissatisfied (PMV/PPD) calculation, ASHRAE comfort tool, or a psychrometric comfort zone chart from ASHRAE-55. The method you pick will likely be determined by the preference and past experience of the mechanical engineer. (See the Resources tab for software options).
Include the following inputs on the LEED Online credit form:
Make design adjustments to meet credit requirements during design development, keeping in mind the potential impacts on energy use.
Make sure that HVAC engineers track and reconfirm credit-compliant operating ranges through the design development phase.
Make sure that the Basis of Design for commissioning reflects compliance with credit requirements and includes design assumptions and load calculations.
Provide ample thermal controls for building occupants. This will increase comfort and occupant satisfaction and will keep operating conditions within the prescribed ranges of ASHRAE-55.
Occupant access to thermal controls can help to meet the credit requirements on a space-by-space basis while increasing energy efficiency (by preventing conditioning of a whole HVAC zone rather than individual spaces) and increasing occupant satisfaction by giving people greater control over their thermal conditions. Increasing occupant satisfaction will help projects that are attempting IEQc7.2.
Variables like clothing levels and metabolic rates are not compliant or non-compliant, but are used instead to determine what appropriate operating ranges will be for a space. You have to show that your HVAC systems will create conditions within these operating ranges.
Confirm required calculations based on the finalized design by using a PMV/PPD calculation, the ASHRAE comfort tool, or psychrometric zone chart.
Complete all required LEED documentation and upload to LEED Online:
Include ASHRAE-55 related performance requirements in the construction specifications.
Provide LEED documentation requirements in the specifications, including the LEED requirements for information contained in O&M manuals and designating the contractor as the signatory for this credit.
Include LEED references in the drawings and specifications where appropriate.
Make sure that contractor-related LEED documentation requirements and activities are in the specifications so that they are accounted for in estimates and bids.
You might want to defer documenting this credit until the construction submittal to confirm the appropriate system installation and inclusion of the required O&M information.
Develop the Systems Manual, O&M manual, or equivalent. Ensure that the O&M manual includes the following:
The contractor is the signatory for this credit, and has to confirm compliance with the bullets above and sign off on this credit.
Be certain that the commissioning agent reviews the OPR and BOD and confirms that system design and installation will meet the credit requirements for operating ranges.
Set up building operations training to ensure that on-going operation of HVAC systems will meet ASHRAE-55, using the O&M manual for reference.
Encourage general contractors and mechanical contractors, commissioning agents and building operators to review O&M materials and maintenance procedures together to confirm that system performance and maintenance meets the original design intent.
Set up training with O&M staff on proper operating procedures.
Excerpted from LEED 2009 for New Construction and Major Renovations
To provide a comfortable thermal environment that promotes occupant productivity and well-being.
Design heating, ventilating and air conditioning (HVAC) systems and the building envelope to meet the requirements of one of the options below:
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.
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 criteriaComfort criteria are specific design conditions that take into account temperature, humidity, air speed, outdoor temperature, outdoor humidity, seasonal clothing, and expected activity. (ASHRAE 552004); 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.
Establish comfort criteriaComfort criteria are specific design conditions that take into account temperature, humidity, air speed, outdoor temperature, outdoor humidity, seasonal clothing, and expected activity. (ASHRAE 552004) according to ASHRAE 55-2004 (with errata but without addenda) that support the desired quality and occupant satisfaction with building performance. Design the building envelope and systems with the capability to meet the comfort criteria under expected environmental and use conditions. Evaluate air temperature, radiant temperature, air speed and relative humidity in an integrated fashion, and coordinate these criteria with IEQ Prerequisite 1: Minimum IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors. Performance, IEQ Credit 1: Outdoor Air Delivery Monitoring, and IEQ Credit 2: Increased Ventilation.
This ASHRAE standard defines the criteria for human comfort that is followed to design mechanical systems.
Information about the ASHRAE Thermal Comfort tool with ordering information.
Information about how to use psychrometric charts.
Download free psychrometric chart software.
Free, easy-to-use program from UCLA that displays climate data in the form of psychrometric charts, among others.
The National Climatic Data Center provides regional weather data that you can use to assess your climate relative to ASHRAE-55 requirements.
This spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated.
These sample documents, from a LEED for Schools 2009 project in Mass., demonstrate how to document that the project meets the thermal comfort design requirements of ASHRAE 55. LEEDuser thanks Christopher Schaffner of The Green Engineer for providing this sample.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
Our project is a major renovation to an existing college faculty office building with very low floor-to-floor heights. The lack of plenum space made air distribution ducts infeasible... however, all rooms have access to operable windows (the building was built in 1914, and was therefore designed for natural ventilation). Heating and cooling is provided by a 4-pipe fan coil in each room. Our application for IEQc7.1 is pending, because the LEED reviewer wants us to demonstrate that the fan coil units that serve the individual offices are designed to handle the ventilation loads with operable windows fully opened. Why would this be necessary? Isn't it safe to assume that an occupant will adjust/close the windows when thermal comfort falls outside the parameters? It seems to me that we should only have to demonstrate that the loads are met with the windows open to meet minimum ventilation requirements. Has anyone else run into a similar situation?
Eric, it sounds like your design is using the windows for natural ventilation and the fan coils for mechanical conditioning. Section 5.3 in ASHRAE Standard 55 outlines a method for using operable windows to naturally condition spaces, but sounds like it won't apply to your design. In that case, I think your fan coils must do the work to maintain thermal comfort conditions, including the heating/cooling/dehumidification loads from unconditioned ventilation air. The windows are for ventilation only, not conditioning.
How much difference is there between the window "minimum opening for ventilation" and fully open? Is it clear to the occupants when or how much they should open the windows?
our project is mixed use commercial building, including office, hotel, retail store, and restaurant etc. All spaces in our project comply with ASHRAE 55 except for commercial kitchen. There is no AC unit there and conditioned air is delivered from adjacent restaurant dining room and exhausted through fan located in the commercial kichen. So the kitchen air is conditioned indirectly. Our question is that the commercial kitchen may excluded from ASHRAE55 evaluation or not. Thank you for your kind advice in advance.
Noriko, I don't see how you can exclude it. See other discussions on this page about excluding high-activity spaces like gyms. LEED really makes you work to exclude occupied spacesOccupied 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..
A new LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. was released on 4/1/13 that is relevant to this credit.
LI #10279 disallows excluding high-activity spaces like gyms, or spaces that normally are not conditioned like warehouses from IEQc7, but offers an alternative calculation method for gyms, and an alternate compliance method for warehouses based on design alternatives such as radiant flooring; circulating fans; passive systems, such as nighttime air, heat venting, or wind flow; and localized active cooling.
I asked our LEEDuser expert Chris Schaffner of The Green Engineer what he thought about this Intepretation. He says it clarifies things, but doesn't help where help is needed: '95% of the people struggling with this are public schools with gyms. They should just make the gyms exempt,'" he opined.
What do others think of this Interpretation?
The LI states that, "an alternative to the requirements of ASHRAE 55-2004 is acceptable" in these circumstances. I recently saw a project team propose the use of a health/fitness facility standard that would appear to meet the intent of this interpretation.
I've been involved in two recent projects which included in one case, indoor tennis courts, and in another case, a fitness center. The interpretation does nothing to remove the vaugeness that existed before. By saying "the project must determine acceptable thermal comfort conditions that meet the intent of the credit, and demonstrate that those conditions will be met" they leave it up to us to propose something and we are at the will of the reviewers opinion. So to me, the interpretation still leaves the credit in "limbo" for those spaces and I can't count on it in our credit/point strategy. We will do a lot of work researching and proposing a set of criteria, not knowing if it will be in vain depending on how the reviewers see it. That's the status of our application now for the project with the fitness center. We're waiting to see how the reviewers treat us.
This area does need work. We have had a couple of projects certified with these kinds of spaces (one had a gym, the other had a fitness room), and we included a narrative on what we felt was the standard of care for these kinds of rooms, higher temperature with air movement, and that seemed successful. Another is yet to be submitted that the whole building is a fitness, training, pool, and therapy building that is a shared facility for a hospital and a community. The pool has pretty good standards for defining comfort, but again the other spaces will fall on our standard of care and typical practice over our experience.
Nadja, your point of not being able to count on this credit is correct. We work to manage our clients expectations on this and other credits so they understand we are making a good faith effort, and giving them what we feel is the best and most efficient design, but we are not GBCI and cannot predict what they will or will not accept. There is a broad range of professional interpretation in our field, and we all must work within it.
Project consist of Heating only system for dinning area (for inmate), and for summer ventilation the unit provides the 6 ACHThe number of times per hour a volume of air, equivalent to the volume of space, enters that space. ventilation air into the area. Project location is in MD.
Since this building is for inmate the owner does not want to provided cooling for dining area.
Can i able to get this credit, what kind of document i need to provide to support.
Thermal comfort standards apply to all humans, regardless of criminal record. If you aren't providing comfort you can't get the credit.
LEED shouldn't be certifying prisons.
I just re-read Nadja Turek's earlier comment (from Aug 29, 2012) which included this excerpt from a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide response:
"The metabolic rate for occupants involved in highly physically activity fall outside the range governed in the standard, therefore, thermal comfort conditions must be based on acceptable practices. The project should utilize an alternative compliance method or extrapolation of existing data to show compliance with the
credit for the spaces which fall outside the range of standard 55-2004.
ASHRAE 55-2010 has a revised computer simulation method which accommodates MET levels up to 5.0."
The problem is, ASHRAE 55-2010 specifically states that only rates between 1.0 and 2.0 MET fit within the PMV-PPD model, and only 1.0-1.3 MET for the adaptive model (see section 126.96.36.199, 5.3 and Appendix A).
The ASHRAE Thermal Comfort Tool v2 software (which follows ASHRAE 55-2010) allows an input value up to 5.0 MET... but it also generates a notice that this rate is not covered by the standard, if you try to enter anything above 2.0 MET. It seems to me whoever responded to Nadja's CIR misunderstood that.
Does anyone have a project that achieved this credit with spaces that fell outside of ASHRAE 55 parameters? Has any direction been given for alternate compliance? James Del Monaco posted his discussion with a reviewer back in Nov 2010, but it seems many are still looking for clarification on this.
I have the same understanding. GBCI shouldn't be asking project teams to comply with ASHRAE 55 when the conditions clearly fall outside the boundaries of the standard. CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide's aren't precedent setting anyway, so I would ignore this and simply state the exception to the standard from Appendix A.
We have been successful excluding zones in some projects that are not covered by ASHRAE 55, and that were outside the bounds of the standard with MET > 2.0. At that point we do include some narrative on what we did to address that condition, and what the standard of practice was for those zones. For example, ceiling fans in a fitness room to increase air movement over machines.
I heard from someone in ASHRAE that the Standard 55 User's Manual is definitely in development and will be "coming soon". Hopefully it will be available later this year?
We are targeting this credit for a project with more than 70% of the buildings are utilised for industrial, processing, storage and manufacturing activities. Does the credit apply to these type of spaces?
I'm currently confronted with the same issue, and I have similar questions:
In the spaces used for processing, the metabolic rate of the occupants as well as their clothing may fall out of the limits of both comfort calculation methods proposed in ASHRAE 55-2004.
Does that mean that this credit cannot be applied for these type of spaces?
Or is there any other comfort calculation method more appropriate (not based on sedentary office activity)?
Or should I just exclude these spaces from the credit scope?
Thanks all for your clarifications.
Ismaiel, it's not the space type but the activity that occurs within those spaces that determines whether this credit is applicable. If the clothing and metabolic rates of the occupants in each space fall within the ASHRAE Standard 55 models, then it applies.
Valentin, based on what I've seen you probably will not be successful with this credit if you have activities/spaces falling outside of the ASHRAE 55 models. I believe projects are unable to exclude any occupied spacesOccupied 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. from the credit scope even if they do not fall within the limits of either the PMV-PPD or adaptive models in ASHRAE 55. See some of the older posts on this thread, as well as the LEED Interpretations database.
(I work mostly on LEED Canada projects, and the CaGBC does allow spaces to be excluded if they can be justified based on the limits of ASHRAE 55.)
Does ASHRAE 55 standard apply to areas with transient occupancy such as smoking lounges in airports, Knowing that smokers will spend less than 15min in average?
No, ASHRAE 55 is intended only to model thermal comfort in a 'steady state' and is applicable when occupants are in the space for no less than 15 minutes.
I've submitted this credit to USGBC and it was rejected. The reviewer stated that the design air speed values exceed 40 fpm and therefore do not meet ASHRAE 55-2004 (I have a range from 50 - 70 fpm). However, i've used two tools that show the scenarios do comply. Climate Consultant 5.0 and the Berkely tool referenced on this site. Air temp of 75F, Mean radiant temp of 85F (large single pane historic windows), air speed of 70 fpm, Humidity of 50%, MET of 1.1, and 0.57 clo. What am i missing? The Climate Consultant graph is hard to follow (this is the one I submitted), perhaps if I submit the Berkely tool it will be more clear to the reviewer? I had a narrative explaining all the values I used as well. Any help is appreciated.
I have researched this more, and have found that air speed values above 40 fpm are allowed but only if Section 5.2.3 are met, which requires occupants to control the air speed. We have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes, so the occupant can slow the air speed by raising the room setpoint. But every occupant does not have their own thermostat, therefore it sounds like we do not meet this credit. anyone have any other thoughts?
Barbara, this credit is not a particular expertise of mine, but at a glance, I wouldn't have thought that controls for individual occupants factor in here. Isn't that under IEQc6?
I thought so too, but ASHRAE 55 mentions allowing "elevated air speeds" above 40 fpm at the occupant level if the occupant has control over the air speed. I am very ready for ASHRAE to publish the User's Guide for ASHRAE 55. I'm wondering if anyone has ever achieved this credit with air speeds above 40 fpm?
Barbara, I've been getting this feedback from LEED as well but I think the LEED reviewers (as well as others below on this forum) are incorrect. Section 5.2.3. is specifically to show the designer that you can maintain thermal comfort with higher ambient temperatures than shown in figure 188.8.131.52. if air speeds are increased above 40 fpm. Their chart shows how high the temperature limit can increase for corresponding air speed increases (and given air and radiant temperatures). I've had to explain this to LEED consultants as well with varying degrees of success.
I believe ASHRAE 55 includes this to provide a guideline to those who would like to design for less mechanical cooling while keeping comfort at the same time. I do not read this to be an absolute that 40 fpm is the comfort limit and any speed over that is uncomfortable.
Discomfort due to draft is covered later in 184.108.40.206. You can see there may be certain circumstances where 40 fpm would be the limit, but not always.
We'll see if LEED agrees when I get a review of my response.
Jeremy is correct that Section 5.2.3 includes provisions for increasing airspeed to offset elevated space temperatures for individual comfort. However, this option is only applicable if the affected occupants can control the airspeed.
What MET rate would you assume for the ASHRAE-55 compliance for retail areas (ie. supermarket, clothes retail)? Customers would be walking about (MET:1.7), while employees would be either standing or seated (MET: 1-1.2). In summary, for whose comfort should retail spaces be designed for, customers or employees?
It is noted in ASHRAE 55 Normative Appendix A (Activity Levels) that each group of occupants must be considered separately, and that it may not be possible to provide an acceptable level of comfort to all occupant groups.
In your case, you would analyze thermal comfort for employees and customers as separate cases, then ensure that you can satisfy both cases.
I am working on a mechanically ventilated manufacturing building in Bangladesh. What is the maximum acceptable temperature for this kind of building? In summer they usually get 36C and a relive humidity close to 70%.
Thank you responding.
You need to perform a comfort analysis to determine the acceptable indoor conditions. It will be based on factors such as activity level and clothing.
36c at 70RH% is certainly far outside the comfort zone.
The IEQc7.2 Cooling Mode table asks for the Design Operative Temperature, Maximum Design Humidity and Design Air Speed for the four seasons (Spring, Summer, Fall, Winter). Is it OK to complete only the Summer values?
Thanks in advance.
No - you need to account for all four seasons. This is one of the main objectives of the credit - to make sure that part-load conditions are being considered and addressed. Humidity control is sometimes difficult to achieve under part-load conditions.
Which software tools are accepted by the USGBC, other than the ASHRAE Comfort Tool (priced at $117)?
Is the tool from Climate Consultant listed under the Resources Tab accepted? What about the Thermal Comfort online tool developed by CBE Berkeley (http://www.cbe.berkeley.edu/comforttool)?
USGBC does not officially "accept" any software tools. If the tools listed are used correctly, they can perform the analysis required by the credit.
Just received an email about a new tool that may be helpful for teams pursuing this credit:
The Center for the Built Environment has developed a web-based thermal comfort tool, which is now available for use: http://cbe.berkeley.edu/comforttool/. This free online tool is useful for performing and visualizing comfort calculations according to ASHRAE Standard 55-2010. The tool has been validated against the official ASHRAE Thermal Comfort tool. The tool could be used for design, research and teaching. The tool works in Firefox, Chrome and Safari. Internet Explorer is not supported.
The link is not opening in chrome & firefox. Any other link to access this tool ?
Is it applicable for only naturally conditioned spaces?
We have a library project and we received the review comments from USGBC and requested to provide the following:
1. A "detailed narrative" describing the thermal comfort design criteria for the project which includes specific information for each thermal comfort zone.
2. Explanation of any special conditions or circumstances that require zones to exceed the ASHRAE ranges.
3. Confirm the compliance approach used (graphical or computer based) to assess occupant satisfaction of all bldg. occupants.
4. If using graphical method, provide documentation. Otherwise, resubmit the credit form using the approach outlined in section 220.127.116.11 computer model method for general indoor application.
Can someone help me on how can i provide those narrative (eg. sample)?
We don't have software that could provide graphical method, what does it mean computer based?
Any input and/or assistance on this is highly appreciated.
"Graphical method" means the chart shown in ASHRAE-55 for the acceptable range of temperature and humidity. (Figure 18.104.22.168)
Provide a narrative explaining that the expected activity levels fall between 1.0 met and 1.3 met, that clothing insulation is expected to be between 0.5 clo and 1.0 clo, and that air speed is designed to be less than 40 ft/min in the occupied zone. (These are the criteria required to use the graphical method, and would be typical in a library). Then demonstrate that temperature and humidity is typically held within the range indicated in Figure 22.214.171.124 during occupied hours.
Section 126.96.36.199 of ASHRAE 55 has all the details.
Thanks for respond. Follow-up question, please:
1. Does it mean, we need to provide the PMV graph or we can use the thermal comfort tool that you've shared as our support document to satisfy ASHRAE 55 section 188.8.131.52?
2. Is there a formula for air speed? How can i get the less than 40 ft/min.
3. I'm using V4.0 credit form, it's not indicated the MET and CLO values. The only info available is space design parameters and local discomfort effect.
1. I think you could use either tool. You could also xerox the graph in ASHRAE and draw a dot showing your design conditions.
2. Air speed is based on diffuser selections. 40 FPM is pretty high. Typically, the diffuser manufacturers data will show data on the "throw"; that is, the limits of different velocities in relation to the diffuser, based on different air flow rates. Ask your HVAC engineer. Unless you are specifically trying to get a cooling effect by using higher air speeds you probably are much less than 40 fpm
3. So put in the space design parameters. Make sure the temperature & humidity you list falls within the comfort zone. Make sure the air speed is less than 40 FPM. Make sure you can back up these claims. For local discomfort effects, check all the "not likely" boxes.
Sorry to bother you.
Just want to make sure that i understand what you're saying. " I can copy the graph from ASHRAE 184.108.40.206 and draw a dot showing my design conditions". What values should i reflect here; the operative and design humidity (cooling and heating) of my space design parameters? Do i need to delete other mark-ups from the graph i.e. Clo, database from ISO etc.)
How about my local discomfort? I think the reviewer want me to confirm the approach used - graphical or computer based aside from check all the boxes.
"What values should i reflect here; the operative and design humidity (cooling and heating) of my space design parameters?" - Yes
"Do i need to delete other mark-ups from the graph i.e. Clo, database from ISO etc.) " - if it makes it clearer, sure.
"How about my local discomfort? " - not sure what you mean. Make sure the air speed is less than 40 FPM.
" I think the reviewer want me to confirm the approach used - graphical or computer based aside from check all the boxes." - this is the graphical method
We submitted a single psych chart with coil conditions and comfort zone range (from 0.5 clo to 1.0 clo), and narrative. We filled out the LEED form with an operative temperature of 73°F for both summer and winter, and the operative temperature lands well into the comfort zone, but more towards the 1.0 clo side.
The project is mechanically conditioned and naturally ventilated. The project consists mainly of residential apartments. The unit has both heating and cooling capability. Humidity is not a concern in the project climate.
The comments we received state that the provided operative temperature of 73°F fall outside the comfort design criteria required by ASHRAE 55, and that we need to provide a narrative to explain why.
We did not indicate a demising line between the 0.5clo and 1.0clo, so the only response we can think of is to do a seperate psyc chart for summer, with a slightly higher setpoint/operative temperature and 0.5clo. This would indicate the deadband that occurs in T-stat settings. But, the review has not explicity stated anything regarding my assumption above, only that the operative temperature does not fall into the comfort criteriaComfort criteria are specific design conditions that take into account temperature, humidity, air speed, outdoor temperature, outdoor humidity, seasonal clothing, and expected activity. (ASHRAE 552004).
Brian, the summer condition at 73F and 0.5clo DOES fall outside the comfort parameters shown in Figure 220.127.116.11 of ASHRAE Standard 55-2004. What point(s) did you mark on the submitted psych chart? What design conditions did you specify for summer and for winter?
The summer design condition and winter design condition should each describe a single point on the psych chart, not a range. You could increase the operative temperature to fall within the 0.5clo zone, or you could use a higher clo value and interpolate using the equations in Section 18.104.22.168 of the standard. I think a 2nd psych chart (or one with both winter and summer conditions noted) should be acceptable.
The LEED-NC 2009 EQc7.1 credit template asks us to document the Project Space Design Air Speed at 3 ft above the floor. According to ASHRAE 55, this should be a maximum of 40 FPM.
However, most air terminal/diffuser manufacturers only publish data for throws down to 50 FPM.
How are project teams expected to document a design air speed at the occupant that is lower than shown the available mfr data without doing a CFD model?
A CFD model is not required. If the manufacturer cannot provide the throw for less than 50 fpm, the additional throw required to further reduce the velocity to 40 fpm could be extrapolated from the available data. Another approach would be to use the methodology described in Section 22.214.171.124 to demonstrate that the local turbulence intensity is low enough that the occupants will not experience discomfort due to drafts. Another route could be to work backwards with the temperature differentials noted in Section 5.2.3 for using elevated air speed to provide comfort at increased space temperatures.
I am working on a fitness center where the temperature is maintained low and the air velocities adequate thru the use of fans.
The ASHRAE tool show that the people that are working out and have a met equal 4 will never be satisfied event with Clo = 0.
Has any one has this situation?
Is there a way to exclude the people that are working out?
Houcine, the computer model method is only applicable for met values between 1.0 and 2.0, so occupancy types such as a fitness centre cannot be calculated. The graphical method is even more restrictive, for only 1.0-1.3 met and 0.5-1.0 clo values.
See James Del Monaco's earlier comments regarding exclusion of spaces with high metabolic rates. In Canada there is a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide to exclude these spaces, but I'm not sure about what is required for a US submission.
Does anyone else have a specific CIR reference or CaGBC instructions on how to exclude spaces with high metabolic rates?
Hi Houcine, Funny...I was just checking in here to see if any new information had been posted about Fitness Centers, updating the post below from James Del Monaco. We put in a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide on a project with included six indoor tennis courts with a spectator viewing area, which was naturally ventilated. We got the following response from the CIR:
"The applicant requests clarification on how to comply with ASHRAE 55-2004 for spaces served by natural ventilation which are outside of the standard range of metabolic rates. The graphic comfort zone in the standard pertains to spaces where occupants have metabolic rates between 1.0 and 1.3 met. The metabolic rate for occupants involved in highly physically activity fall outside the range governed in the standard, therefore, thermal comfort conditions must be based on acceptable practices. The project should utilize an alternative compliance method or extrapolation of existing data to show compliance with the
credit for the spaces which fall outside the range of standard 55-2004.
ASHRAE 55-2010 has a revised computer simulation method which accommodates MET levels up to 5.0. Therefore, if the project team wishes to use that
standard as an alternative compliance method to show compliance with the credit, that would be acceptable. It is unlikely that a relative humidity of 80% would be considered acceptable for the indoor tennis courts. The ASHRAE 55-2004 graphic comfort zone, and computer modeling method show that people feel increasingly uncomfortable as humidity levels increase.
Keep in mind that this credit is meant to promote thermal comfort as measured by a defined standard. If the project cannot provide thermal comfort for a number of its occupants, it should not necessarily be allowed to exclude those occupants. The remaining spaces, including offices, locker rooms, lounge areas, and spectator seating areas should be designed to follow compliance with ASHRAE 55-2004. These spaces should be documented separately in the credit documentation."
Ultimately we decided not to mess with documenting EQc7.1 on that project based on the CIR comment about 80% humidity, which we couldn't get under without A/C. Now I'm about to document another project with a lab on the top floor and a fitness center in the basement. Before we dropped more $$ and bought ASHRAE 55-2010, I checked in here to see if anyone had new guidance on fitness centers and found your question. So I guess our best path forward is to use the revised computer simulation method from the 2010 version, which accommodates MET levels up to 5.0, based on my CIR. Based on the CIR above, it doesn't appear they are likely to allow us to simply "exclude" these areas.
I having the similar situation where my project include space with MET > 2.0. ASHRAE 55-2010 tool seems not to accommodate MET > 2.0 as this condition apprently is not covered by ASHRAE 55-2010.
Appreciate if you can share your submission approach on this situation.
Do the fitness center users occupy the space for less than an average of an hour per day per person? The IEQ Space Matrix indicates (footnote #2) that if that's the case, the space type should be considered not regularly occupied for IEQc7.1 purposes.
Can anyone point me towards a protocol for establishing correct values to be used in the MRT (mean radiant temperature) sheet of the ASHRAE Thermal Comfort Tool 2.0? It asks for the temp. and emissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature. of the “Glass/Panel Data”. There are so many factors to consider in order to establish that temperature. Do I need to do a Therm model on the window and frame and use the value the coldest point as in the PH standard? Or do I try using a weighted average of frame and glass? Or can I get by with just the glass temp. Thanks in advance.
Note: The help menu for the thermal calculator tool does not work with my computers operating system so I apologize if this is covered there.
I haven't been able to access the ASHRAE Thermal Comfort Tool v2 software help menu either. Look for a "Final Report 1332-RP" PDF that is saved in the same folder as the software -- it appears to include text from the help menu.
I typically use the assembly (glazing and frame) U-valueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. and design indoor/outdoor conditions to calculate an inside surface temperature. I use the same equation for all exterior surfaces, each with their respective U-value. For lack of other info, I leave the emissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature. at the default values (0.90 for opaque surfaces, 0.84 for glass). If you have separate temperatures for the glass and frame, I think an area-weighted average should be fine.
ASHRAE is working on a User's Manual for Standard 55, which (if I read the RFP correctly) should be available in early 2013. It will include explanations and example calculations on how to apply the Standard. You could also send an interpretation request to ASHRAE.
Lindsay: Thank you for your reply. Unfortunately, I did not get the "Final Report 1332-RP" PDF file on my recently purchased copy of the Thermal Comfort Tool. Not sure why not.
My next hurdle is to identify the appropriate exterior boundary condition for my Therm models. I have searched the internet and have found no definitive source for that temperature value. Any ideas on that? I could see using 28.6F which is the average monthly temperature for the coldest month as calculated by NOAA.
Look in the folder on your hard drive where you installed the software, not on the CD. The PDF should be included with the installation when you ran the EXE file.
For the exterior boundary condition, what outdoor design temperatures were used to size the HVAC systems? These should be documented as per ASHRAE Standard 55 Section 126.96.36.199 and often reference published ASHRAE climatic data (99.6% heating design temperature, 1% cooling design temperature and humidity) or local code requirements. It looks like NCDC/NOAA also publishes an Engineering Weather Data CD-ROM. Use your own judgement for spring and fall design conditions -- the main concern then is high humidity and whether the HVAC systems have enough dehumidification at part-load.
As an aside, do you have radiant heating or cooling in your project? If not, and since you mentioned Passivhaus, your project may have a good enough building envelope that you can assume the operative temperature is equal to the indoor air temperature, and avoid calculating the MRT altogether (see Standard 55 Appendix C for details).
I'm facing with a question about the room Mean Radiant Temperature (MRT): Is there any spreasheet that calculates the MRT and than the Operating Temperature?
The ASHRAE Thermal Comfort Tool v2 includes a Mean Radiant Temperature calculator. The software CD may be purchased directly from ASHRAE, and the cost is $117 ($99 for ASHRAE members). There are other tools available, but I'm not familiar with them or how they handle the MRT.
The operative temperature is calculated as per Appendix C of ASHRAE Standard 55-2004. This calculation is dependant on the relative air speed, air temperature and mean radiant temperature and is pretty straightforward.
In my opinion, the decision on what values to use for the MRT calculation is perhaps the most difficult step in thermal comfort analysis.
The ASHRAE Thermal Comfort Tool V2 software is based on ASHRAE 55-2010, but LEED-2009 uses 55-2004. Does anyone know if the comfort tool software output is accepted for this credit even though it is based on 2010?
I'm also curious about this. I'm working on a number of Canadian projects and haven't been able to find feedback from US or Canadian users (or reviewers) regarding the acceptability of ASHRAE 55-2010 and the Thermal Comfort Tool v2 software in place of ASHRAE 55-2004. Does anyone here have any info?
For a building that has a specific requirements for manufacturing areas to be at temperature/humidity setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. that fall outside of ASHRAE 55-2004 is there a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide that anyone else has found that allows you to identify and exclude certain areas for IEQc7.1, yet still achieve this credit?
Keith, there are no published LEED Interpretations for this credit. I don't know how other projects have handled this. Any other input? Or have you managed this somehow since posting?
Two questions involving credit IEQ 7.1.
1- In Table IEQc7.1-2 cooling mode: when they ask for the design operative temperature in winter season what do they mean? Is the design set point for winter? (1) or is the design temperature in case of an exceptional hot day in winter in which the HVAC equipment may actually have to refrigerate? (2)
In the sample uploaded the design temperature for cooling mode is the same in the four seasons (as in the heating mode), in case this is correct then option 2 of my cuestion will be the correct answer?
2- Restrooms should be analysed for this credit?
Thanks a lot
Hi, im working in version 4.0 of this credit template. The opportunity to choose between the following is given:
"provide outputs from Load Calculation software or design spreadsheets that incorporate, at a minimum, space type, activity level, design operative temperature (heating/cooling), design humidity range (heating/cooling), and design air speed."
“Project will use Table IEQc7.1-1 to document space design parameters. Each room type in the project is only required to be listed”
When choosing the first alternative the following is required:
Upload IEQc7.1-1. Upload appropriate Load Calculation Software outputs or design spreadsheets. See Credit Resources for acceptable programs and the required outputs.
But the Credit Resource tab does not provide any further information.. Do anyone have knowledge regarding what kind of programs that is acceptable.
If possible, can information from the energy program used for EAp2/c1 be used?
If the second alternative would be our compliance path, we would have to list around one thousand different room types. Would it be possible to only list a sample of rooms to show compliance due to these circumstances?
The documentation requirements vary based on the type of HVAC systems and building occupancies. With either alternative, it is reasonable to group together spaces with similar activity levels, design temperatures, and anticipated attire. For example, a typical office building may include offices, conference rooms, workrooms, break rooms, corridors, storage rooms, and restrooms. Although the metabolic rate will be higher in the some spaces (e.g. corridors and workrooms) than others (conference rooms and offices), the anticipated attire and design temperatures are likely similar and the information can be provided as a range of conditions. Even in an office environment, the typical clothing allowance for male and female employees is likely to vary. Alternatively, a school may contain spaces with significantly different activity levels, clothing allowances, and/or space design temperatures and require reporting different design criteria for several space types (e.g. gymnasium, classrooms, cafeteria, etc.).
Generally, it is sufficient to provide the design parameters used to determine the indoor design conditions (activity level, clothing allowance, etc.), the program with summer and winter indoor and outdoor design conditions used to size the HVAC systems. Additional information on how humidity will be controlled during low cooling load conditions may be required for packaged single zone equipment and facilities using natural ventilation strategies, but in some climate zones humidity is not an issue. The acceptable load calculation software would include programs that can perform the simulations required for EAp2/c1, but is not necessarily limited to those programs.
Does anyone have any experience or guidance for documenting compliance with ASHRAE 55 with a mechanically conditioned, naturally ventilated building? When windows are open, the required humidity levels may not be achieved depending on the time of the year. Humidity control with natural ventialtion is the only issue we are having with this credit.
Hi Carly, have you received any comments on this. I have the same problem with a residential tower that uses natural ventilation but Mitsubishi split system for space conditioning. The LEED form does not adequately address this situation. Any guidance would be appreciated. Thanks!
There is a new ASHRAE 55 Compliance app for the iPhone/iPad, similar to the ASHRAE Thermal comfort tool. It calculates PMV and PPD for the LEED IEQc7.1 submittal. At only $8 its much more affordable than the previous software. I was wondering if anyone had used it and has any feedback?
Is it possible to show a sample calc for credit 7.1. I am not sure how to calculate this and would welcome any insights as to how about providing this calculation. I was hoping to not have to pay the membership fee.
Robert, our content is made possible by everyone's membership fees—and we appreciate the support. There is a sample available in the Doc Toolkit, and I can't give it away.
1) Thanks to LEED User for uploading sample documentation. This was very helpful.
2) the M&E working on the project would like to demonstrate compliance using a software program. Are there any programs (best if free) you recommend?
Any idea as to where can thet get the ASHRAE Thermal Comfort Program from ?
3) From the documentation provided, I noticed one called "Psychrometric Analysis for Induction System, that is an output of HAPv 4.4 . Would this suffice to document compliance ? Or do we need to upload the results from the ASHRAE program tool as well?
Many thanks for your help,
This brief guide introduces some of the key variables involved in designing for thermal comfort.
Principal & Founder
The Green Engineer, LLP
Teams must achieve IEQc7.1 in order to earn IEQc7.2. IEQc7.2 offers an opportunity to confirm that the system design and ASHRAE-55 requirements are working to deliver occupant comfort.
Providing thermal comfort controls will help occupants be comfortable on a space-by-space basis.
Commissioning will help confirm that equipment set points and operating ranges will create system performance that is consistent with the design intent.
Ongoing measurement and verification of mechanical systems will confirm that systems are operating as designed and at levels that maximize efficiency and occupant comfort.
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