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?

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..

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.

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 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'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?

Hi Ismaiel,
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 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 5.2.1.1. 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 5.2.4.2. 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.

Hi Omer,
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.

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.

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.

USGBC does not officially "accept" any software tools. If the tools listed are used correctly, they can perform the analysis required by the credit.

Hi Christopher,

The link is not opening in chrome & firefox. Any other link to access this tool ?

Is it applicable for only naturally conditioned spaces?

"Graphical method" means the chart shown in ASHRAE-55 for the acceptable range of temperature and humidity. (Figure 5.2.1.1)

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 5.2.1.1 during occupied hours.

Section 5.2.1.1 of ASHRAE 55 has all the details.

Christopher,

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 5.2.1.1?
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.

thanks,
susan

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.

Hi Christopher,

Sorry to bother you.
Just want to make sure that i understand what you're saying. " I can copy the graph from ASHRAE 5.2.1.1 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.

thanks again.
Susan

"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

Brian, the summer condition at 73F and 0.5clo DOES fall outside the comfort parameters shown in Figure 5.2.1.1 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 5.2.1.1 of the standard. I think a 2nd psych chart (or one with both winter and summer conditions noted) should be acceptable.

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 5.2.4.2 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.

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.

Hi Nadja,

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.

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 6.1.1.1 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).

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.

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?

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?

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.

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.