Agree with you chicopee, but in my opinion that would still be oversizing the system just to accommodate the exhaust requirement, essentially 133 SF/ton or 15 Air changes for a retail space.
I think the intent of the code was to not pressurize the building or, in the instance that a unit might...
Thanks for the replies.
Kiwi - The 1/3 OA is directly from the code. I was getting hung up on being told by these guys that the exhaust rate was 1 CFM/sq ft at all times.
For example, what they were saying is a 600 sq ft room would require 600 CFM of supply air. 1/3 of this, 200 CFM (min.)...
My first thought was that "exhaust" in the code perhaps meant return air, but I spoke to the building department and they gave the 1/3 - 2/3 explanation.
I can't think of a reason to require exhaust to the outside in addition to ventilation air. It doesn't make sense to me from a ventilation...
We are designing for a retail store in Chicago.
Things I know so far: The code calls for 1 CFM/sq ft supply and exhaust. The exhaust is required to go to the outside atmosphere. Also required is that 1/3 of supply air be from outside, while the other 2/3 can be recirculated.
My question is...
