I would like to confirm if flush-out calculations should be based on gross or net floor area of the building. In the reference guide it is written that we should "perform a building flush-out by supplying a total air volume of 14,000 cubic feet of outdoor air per square foot of gross floor area". However in the example section of the reference guide in the table "Example 1. Option 1, Path 1, flush-out before occupancy calculation" Net office area is provided. Net floor area seems to be more resonable for flush-out calculations. Could you confirm that?
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium for
Calie Gihl
Design EngineerLEEDuser Expert
19 thumbs up
May 31, 2018 - 12:23 am
Hi Agata,
On page 688 of the reference guide, under the Step by Step guidance for Option 1, Step 2 - it says "Use the gross square footage to calculate the total cubic feet of air required." I see where you're talking about where it says "net" in the table - but I'm not sure what their definition of net is there. Can you describe why you think net might be more reasonable, and for your example what the differences between gross and net might be?
Agnieszka Rylska
GO4IT SP Z OO SP K29 thumbs up
June 5, 2018 - 6:07 am
Hi Calie,
I assume that gross floor area is a square footage including the area covered by interior and exterior walls. In my understanding net floor area (without inclusion of walls) is more reasonable for this credit because only the net floor are can be flushed-out. What do you think?
Calie Gihl
Design EngineerLEEDuser Expert
19 thumbs up
June 5, 2018 - 12:05 pm
Agata -
I had not heard of that definition before, so I just did a quick search and found this: "Net Area is the actual occupied area not including unoccupied accessory areas such as corridors, stairways, toilet rooms, mechanical rooms and closets." I do not see a definition including or discluding the area under wall thicknesses, but to me this seems like a trivial area. You can count all of the space as defined by LEED without including the area under wall areas.
Dionisio Franca
DirectorWoonerf Inc.
30 thumbs up
July 19, 2018 - 8:04 pm
Hi Calie and Agata,
It seems to me that net area is used in the UK. You will need it if documenting a BREEAM project. Small discrepancies in area are usually accepted by LEED reviewers, if it is small in percentage, so excluding the walls probably will not be an issue. It is good to explain to the reviewers why the areas are different though.