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FAQs about IEQc7.1 :

ASHRAE-55 comfort criteria ask for space air speed. Is this the same as the supply air volume measured in cubic feet per minute (CFM)?


What should I do about a warehouse space?

How can thermal conditions for areas with metabolic rates outside of 1.0–1.3 be determined? (Per ASHRAE Standard 55-2004 Section 5.2.1.1, Figure 5.2.1.1 can be used for areas with metabolic rates between 1.0 and 1.3).

There are a few spaces in my project that can’t meet these requirements. Can’t I just exclude them?

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NC-2009 IEQc7.1:Thermal Comfort—Design

Air diffuser for an office building

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Maya Karkour
EcoConsulting
LEEDuser Basic Member
549 thumbs up

Dear All, I have a couple of questions regarding this credit: a) How can I convert the air velocity at the diffuser outlet to the air velocity reaching the occupant, knowing that an open plan office will have several desks and some occupants will be closer to the diffuser than others? Do I take average location in the middle of the room? b) The diffusers for my project are located just below the ceiling level (around 9 feet above floor) whereas I need to report the air speed at the seating level of occupants (3 feet above floor). Do you think diffuser manufacturers will have these values / conversion formulas? c) The Mechanical Engineer confirmed that this is a typical project with a typical HVAC design strategy. Can I assume that the air speed is 40 feet per minute (as a default value) without further documentation to the USGBC, given that they don't ask for any documentation? Thanks! Omar

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Julia Weatherby
President
Weatherby Design & Co. Engineers
LEEDuser Basic Member
67 thumbs up

Wed, 08/27/2014 - 16:07

Omar- For a typical project in an office building with typical HVAC design, yes, I believe it is probably acceptable to presume the air speed is 40 fpm. If you want to analyze it more completely, then you can read the introductory information in a diffuser catalog like Titus to evaluate air flow patterns and throws / air velocity at various distances, heights, and supply air temperatures.
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Kathryn West
LEED AP BD+C, O+M, Green Globes Professional
JLL
LEEDuser Basic Member
112 thumbs up

Thu, 06/04/2015 - 16:21

Ghaith, What ended up happening on your project? Did you have to provide justification for the 40 fps?

Tue, 05/13/2025 - 10:55

Use air diffuser throw data or ASHRAE guidelines to estimate air speed at 3 feet. Manufacturers can help. Assume 40 fpm only if supported by typical design and engineer confirmation.

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