Multiple fixture types in a common space

Zachary Goodnough

LEEDuser Basic Member

16 thumbs up

August 27, 2012

In each bathroom of our project building there are 5 blow-out fixtures and 1 standard water closet that is handicapped accessible. The two types of fixtures have different flush rates. In my submittal, I included both fixtures under the same fixture family and fixture group and then altered their usage rates to be proportional to the amount of each fixture. In other words, I had the blow-out fixtures being used 5 times more than the standard water closet. My LEED reviewer has said that in order for the calculator to perform correctly, there can only be one fixture from each fixture family to each fixture usage group. It sounds like they want me to figure out a how big the subset of the building population is that uses the handicapped accessible toilets, but I’m not sure how feasible getting that number is. Would another acceptable solution be to use the average of all fixture flush rates? Any other thoughts or comments would be greatly appreciated. Thanks

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Jessica Hawley

Sustainability Consultant

LEEDuser Basic Member

43 thumbs up

Mon, 08/27/2012 - 12:30

I think the issue is that you assumed the handicapped (HC) fixture would only be used by the HC population, which is often untrue. The calculator will do the math for you, so don't manipulate any of the usage rates. Just list each type of fixture within the fixture family, it's associated flush rate, and let the calculator do it's thing. I would not average the flush rates. I have been seeing this method rejected more and more frequently.

David Sheridan

LEED Specialist

USGBC

LEEDuser Premium Member

14 thumbs up

Mon, 08/27/2012 - 15:40

If you include blow-out fixtures and conventional WCs in one fixture group the water calculator will double count (it will apply the entire occupancy to both kinds of fixtures). The fixture group is intended to identify the occupants who will be using a particular type of fixture, so you need to designate the number of FTEs and transients who will be using the HC WCs. I agree with EBI that this number does not have to be the actual number of handicapped occupants, as non-handicapped occupants will also use the fixtures (unless access is restricted). So set up two fixture groups and split the FTEs and transients between them, perhaps on the basis of proximate floor area. Explain in a narrative so the review team can understand your rationale. Blow-out fixtures begs a different question: why are you using them? Are you certain that the WCs are blow-out fixtures and not conventional WCs?