NC 2009 IEQc7.1: Thermal Comfort—Design

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.

Sari, I think if you download the LEED Online form and follow the succession of checkboxes, your documentation requirements will be clear.

Ok, i have made some research in internet and it seems that to document compliance with ashrae 55, i will need to make some simulations to assess that in worst case scenarios of the year or for each mean temperature of each month (i am not sure) the interior temperature is in comfort ranges. Am I right with this? Does anybody know what software are approved by GBCI for simulations of thermal confort documentation?

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!

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.

Hello all,

Any updates on the above ?

Are there any other software program than the ASHRAE Thermal comfort tool (which cost 94$) that could be used to demonstrate compliance and output results such as the ones shown?

Many Thanks,

I am also looking for the same thing. We spoke to ASHRAE Bookstore over the phone and they stated the ASHRAE Thermal Comfort Tool is not compliant with ASHRAE 55-2004. They stated a new version of the software is supposed to come out any day now but they aren't sure when and I don't have the time to wait. Mainly I am a little lost on how to document compliance for spaces that don't have metabolic rates between 1.0 and 1.3 met, using the PMV/PPD calculation. 55-2004 5.2.1.1 states we cannot use the graphical method if we fall outside these ranges. Any help would be greatly appreciated.

Thanks,

Would be great to get some inputs from LEED User regarding the above...

I just downloaded the free tool from Climate Consultant listed under the Resources Tab, Software Tools part of this credit here on LEED user. I have not submitted this to USGBC yet, but it seems to be a fairly easy way to input CLO, MET, and expected velocity from fan-forced systems, and get a psychrometric chart with the two comfort boxes outlined (one for winter clothing and one for summer clothing).

Brandon - also scroll down to a discussion on how to show compliance for a small fitness area of a larger office building. James Del Monaco posted some helpful information on how to document since MET falls out the ranges of ASHRAE 55.

Hi all. I joined so I could see this completed LEED Online form in the toolbox with matching psych charts. My first question is: Everything on the LEED online form seems to match the ASHRAE 55 calculations EXCEPT the air velocity - noted as 200 fpm on the LEED online form, but a mere 19.7 fpm on the calculator...? What am I not understanding that would allow everything between these two to match except the air velocity? (what I'm currently hung up on my current project)

My issue is that we have become accustomed to designing per ACCA Manual D specifications to meet CalGreen standards which note recommended air velocities to be at 600 fpm. Obviously 600 fpm is extremely high compared to 40 fpm, but this project was certainly not designed for such low velocities (the diffusersIn an HVAC context, diffusers disperse heating, cooling, or ventilation air as it enters a room, ideally preventing uncomfortable direct currents and in many cases, reducing energy costs and improving indoor air quality (IAQ). In light fixtures, diffusers filter and disperse light. would have to be literally giant)? The design reviewer is requiring the "Computer Model Method must be used to evaluate draft risk for local discomfort, and make operative temperature adjustments for elevated air speed." I would prefer to not go buy more software to document this credit. I saw the "comfort calculator" but as noted it was unclear whether it would be accepted by LEED Online. Any help or feedback would be greatly appreciated, thank you so much, I'm fairly stuck and this is the last hurdle for the design phase.

Where are you measuring the air velocity? 600 FPM sounds like a duct velocity. What we care about here is the velocity at the occupant, not in the duct or at the diffuser discharge. 600 FPM = 6.8 MPH.

Eric, I just posted several sample documents for this credit (including ASHRAE 55 calcs and the LEED Online form, filled out) to the Documentation Toolkit for this credit (see the tab above). Thanks for asking!

Jill, unforutnately LEEDuser does not currently have any samples that we can post, but we are working on it. If anyone reading this would like to volunteer a sample (and attain everlasting glory), please contact me.

Jill, you can now see sample documentation above in the Doc Toolkit.

I think it's misleading that the RG says the "no calculations" are required. Clearly a bunch of calculations and numerical analysis are required.

I am still confused about how much documentation is needed for this credit. The template states, "Upload supporting documentation with PMV/PPD calculation, ASHRAE 55 comfort tool results, and/or psychometric comfort zone chart from Standard 55." Is the PMV/PPD calculation enough or are we required to upload one of the other two also? The "and/or" makes it unclear. I'm not sure what kind of results you can get from the ASHRAE 55 comfort tool and I really don't want to spend $117 to find out that I could get the same results on my own. Can anyone give me a description of the input required and the output obtained from this tool? And is it absolutely required for this credit?

Not completely sure about the comfort tool - I don't use it personally.

Depending on climate you may want to submit psychometric charts, to show how humidity control is being accomplished, especially at part load conditions.

I think, if you can show:
1) what the comfort zone is for your space type and use,
2) the range of thermal and humidity conditions, how they are achieved, and that they match the comfort zone,
and 3) that the air distribution has been designed so that excess air movement is not a factor,
then you should be all set.

The comfort tool might help if you have an unusual space type, or are attempting to show adaptive thermal comfort, but is probably more than is needed for typical occupancies.

The ASHRAE Comfort Tool was created in 1997 and is made for a Windows 95 Operating system. It is not compatible with 32 or 64 bit machines (xp, vista, windows 7...etc.). It also pre-dates the standard 55-2004 document and so compliance is questionable.

The Credit Form asks for operative temperatures for both cooling and heating, for each season. For a mechanically conditioned building, your operative temperatures will be the same as the cooling and heating 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. unless you are doing something unusual. So use the same temperatures across all four seasons.

hi Mike,
Would you mind to share the template of psychometrics that you've submitted. I cannot finalize my IEQc7.1 template. Appreciate your support - susan

I tried to sent email to ANSI/ASHRAE on how can i do the samples they've provided under "Normative Appendix D – Computer Program for Calculation of PMV-PPD”

And here is their respond:

Your inquiry was forwarded to me in the Technical Services department of ASHRAE. The program in Appendix D references an ISO Standard 7730. ASHRAE does not publish a software program with the ability to generate these graphs or run the code. ASHRAE is developing an update to the ASHRAE Thermal Comfort CD that will allow use of the PMV-PPD method but it will not be available in the immediate future.

I apologize I cannot be more helpful.

Sincerely,
Steve Hammerling

Technical Services Engineer

Not sure anyone can post a psych chart.

I typically provide a psych chart that shows coil selections at full, and part load conditions. The purpose is to illustrate that adequate dehumidification will occur.

My advice is to only provide what has been specifically requested in the credit form on LEED Online. In this case none of what you have mentioned is required. Go look at the credit form.

Susan, what specifically are you not sure about?

You may find our tipsheet on Understanding Thermal Comfort Factors useful.

Tristan,
The LEED form requires me to fill-out the CLO and MET for Spring, Summer, Fall and Winter based on space activity type i.e. libraries, office space, etc..

Does it mean we need to make assumptions for each season based on the # of occupants? How will i categorize it for male and female? This looks tedious on our part.

thanks.

It sounds like you understand what is required.

MET should be identical in all seasons. CLO will not be. We typically don't breakdown male vs. female.

I understand the requirement, but i don't know how can i get the data for CLO.

If you don't breakdown the male vs. female, then why the ASHRAE 55-2004 standard, itemized the garment insulation between male & female?

Also, from your tipsheet of understanding Thermal Comfort Factors, it was mentioned that CLO can be determined based upon entire outfit, and/OR by summing the total CLO values for each article of clothing?

Can i just select from 0.5 to 1.5 ranges given by ASHRAE 55 standard?

So, no one can help me on this information?

Thanks.

As part of ASHRAE standard 55, in appendix B, there are tables B1 and B2. Table B1 has clothing values for typical ensembles and table B2 has itemized clothing values. If you see a clothing ensemble in Table B1 that represents the typical clothing your occupants wear then you can use the value from there, otherwise you can use an itemized list of clothing and sum those values to achieve the overall clothing level for the occupant(s). Also, depending on the project, you should consider breaking down the occupants between male and females, although this is not required. If both males and females would be wearing similar clothing levels, then there is no need to separate them. ASHRAE 55 does not state that men and women are separate. You would need to examine the clothing values and metabolic rates for all occupants, and if they happen to be different for male, female, or even some other breakdown, then that is how you break it down. Depending on where your clothing values end up (and also your metabolic rates), you can determine if you should puruse the graphical method of the computer model method. You have to evaluate if you fall between 0.5 and 1.5 Clo, because there are instances where you would fall outisde this range. Hope this helps.

Thanks James, appreciate your inputs.

Here's my follow-up questions:

1. The template requires 4 seasons, so i will make a breakdown for each of them per occupants?
2. This is a Library, we never know how many males/females should come in. So, how can we determine the values of males/females?
3. I found sample table from ASHRAE 55, do you have an idea as to how do they get those values, maybe i could use it as reference?

Susan,

1. You need to fill in the template for all 4 seasons. you would need to breakdown each season for the occupant breakdowns based on your project.
2. This credit does not care about quantity of occupants (males/females/or other breakdowns). It only cares about the different types of occupants. Like I mentioned in my earlier post, if males and females wear the same clothes and are performing the same activity levels (and therefore the same metabolic rate), there is no need to separate males and females. For example, in a kitchen, males and females may be required to wear the same chef clothes and would be performing the same activities, then they would have matching clothing values and metabolic rates, and there would be no need to separate them. Quantity of occupants is not the concern here with regards to ASHRAE 55. Other LEED credits are concerned with quantity of occupants, but not this one.
3. Refer to the tables B1 and B2 I mentioned in my previous post. Table B1 does give you sample ensembles of clothing. You can use these values if your project has similar clothing. Otherwise you can use Table B2 and sum up the clothing values for whatever clothes your occupants will typically wear. I should note that you should select the clothing values based on normal occupant attire. You should discuss with the Owner what their dress code is. You don't need to address abnormalities in the dress code, you should do what is standard based on the Owners requirements. For one office the dress code may be dress slacks and a button down shirt while for another office it may require a suit and tie. These are both offices but would have different clothing values. It's all based on the dress code for that particular project.

James, you can submit 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 GBCI, and/or use the "Feedback" link or hotline number on LEED Online to get in touch with them. Let us know what you learn!

I am working on a very large (175,000 sf) office building with a small (400 sf) gym also, so am eagerly awaiting what you find out about this!

Tristan, I actually met with one of the GBCI reviewers last week at Greenbuild and asked him how he (and the GBCI) view ASHRAE 55 with regards to gyms and similar type spaces (e.g. kitchens) that fall outside the metabolic rate and clothing ranges listed for using the graphical method and computer model method. In spaces like these, the GBCI understands that occupant comfort is not necessarily the driving factor for design and ASHRAE 55 does not give us a method of compliance, since it was generally written for office spaces. No matter what a designer does in a gymnasium, occupants working out will not be able to achieve thermal comfort according to ASHRAE 55. However, the GBCI informed me that as long as we show them that we put some thought process into thermal comfort in these spaces then they will accept that. The design in these spaces will need to address air speed, temperature, etc. One example we discussed was a gymnasium with spectator seating. Obviously if you increase the air speed too much in the gym, the sporting participants would be more comfortable, but the spectators would then be uncomfortable. The same would hold true for air temperature, if we lower the air temperature to make the sporting participants more comportable, the spectators would most likely be uncomfortable. As long as we make good design decisions in these spaces and document it including a narrative about the design intentA written document that details the ideas, concepts, and criteria that are determined by the owner to be important to the success of the project., then we should be covered. In another example we discussed, we have a 600 SF gym which is part of a 30,000 SF office TI. For this project we added space fans in the small gymspace in addition to making good decision decisions for the air speed and temperature from the house system and that would show that we thought about occupant comfort in this space and would therefore comply.

One important note from the reviewer was that providing a narrative and explaining the background and design intent was the best method of communicating with them our intent.

This is the direction I was given at the Greenbuild from a GBCI reviewer. I am submitting my project this week so I won't know for sure what the final outcome is from the actual review, but I feel better knowing I have some direction and can at least reference my discussion with the GBCI Reviewer as a reason for pursuing the credit using this path.

Hi James, I am wondering whether you received a review response to the GBCI reviewer's recommended approach for dealing with metabolic rates in the 600 sf gym? We are working with a project in which work activities for a number of employees exceed the rates designated under ASHRAE 55. We would be interested to know how the narrative approach describing background and design intentA written document that details the ideas, concepts, and criteria that are determined by the owner to be important to the success of the project. was received during an actual review.

"Can I exclude the warehouse from consideration for this credit?" - No

You may want to keep a look out for the Warehouse "adaptation" coming soon. I believe it addresses this issue.

What is the Warehouse "adaptation"? Is this going to be part of ASHRAE Standard 55 or a LEED ruling? Where would we look for this?

Is it a High BayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. warehouse ?

The LEED Adaptations are basically versions of LEED for specific building types. Think "LEED for Warehouses"

Is there an update on the status of alternative compliance for warehouses? Controllability of systems and thermal comfort have both been very hard to achieve in all of our large mixed-use spaces like this. I am working with a client in food and beverage on a large manufacturing and high-bayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. warehouse base, with a multi-story office in the plant. All spaces will comply with at least the minimum 30% over ASHRAE 62.1, offices will comply with ASHRAE 55, but the energy required to condition the warehouse and production space would make this not be advisable. The mechanical ventilation in the warehouse and production area is zoned, based upon occupancy, and the dual-speed fans are controllable VIA a hand switch or by the BMS. I have read the 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:

http://www.usgbc.org/LEED/Credit/CIRDetails.aspx?RequirementID=709

And even though they had a similar problem, GBCI really sidestepped the issue as it assumed natural ventilation, which in food processing is not an option due to strict pest control.

In our opinion, the dual speed fan would comply with the intent to provide increased thermal comfort, but it is a hot/humid climate near the equator, so without conditioning, we would never get in the right range of comfort for ASHRAE 55. Any input?

You should take a look at the current public comment versions for the next (2012) LEED Update (available at USGBC.org). They include draft language for all the proposed adaptations (Warehouse, Hospitality, Data Centers). You might want to try to use the draft 2012 language as an alternative compliance path.

I think you are talking about EQp1, rather than EQc7.

But yes, the form does the calc wrong, applying both zone level and system level adjustments to each zone entered.

We just check the alt compliance path box, and upload our spreadsheets.

The template is looking for the airspeed experienced by the space occupants. If there is wide variation I would either use the maximum, or split a space into two different space types.

Thank you for the response Chris, but I have a mechanical engineer that is desperately confused. I proposed a rate for the People Outdoor Air Rate of CFM/Person, and he responded with the following: The ventilation airflow rate and the air speed within the space are two entirely different subjects. The outdoor airflow rate is the volume of air being introduced into the supply air stream. This is dependent upon the number of occupants estimated for a given space. The design air speed that we are looking for is what the linear rate of movement of air within the space is, independent of volume.
Can you please clarify how this occupant air speed is determined? I appreciate the help!

Your mechanical engineer is correct. For this credit, we care about air movement, as it has a direct impact on comfort. So air speed, not volume.

The engineer should be able to estimate air speed, based on diffuser selection.

So for an open office it would be ok to use airspeed at one interior diffusser and one at perimter and both at seating level or standing level in the office.

Thank you for the detailed answer. Am I interpreting this right, that it is an average from multiple diffuser points within the breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.1–2007)? This is a Federal project with a complex program, but most of it is open office. Will this rule apply similary in all spaces?

Thanks!

Aplogies my comment was supposed to be a Question if one can use 2 diffuers and average the velocity

I think y'all are overthinking this one. ASHRAE 55 allows "elevated air speed" to be used as a way to reduce the "operative temperature". In other words, you can tolerate higher temperatures by increasing air speed. But practically no effect occurs until you are in the 100 + FPM range.

Diffuser manufacturers usually show the "throw" of the diffuser at different air speeds. Unless, you are trying to use elevated air speed to shift the comfort zone, just make sure you select the diffusersIn an HVAC context, diffusers disperse heating, cooling, or ventilation air as it enters a room, ideally preventing uncomfortable direct currents and in many cases, reducing energy costs and improving indoor air quality (IAQ). In light fixtures, diffusers filter and disperse light. to keep the air speeds where people are nice and low, then enter a nice round number in the table - something below 50 FPM. At that range it doesn't really matter if it is actually 20, or 30, or 42.8. As long as the air speed is low enough to have no effect on the comfort zone, it doesn't much matter for this credit.

Clear as mud?