90.1-2007 Addendum dn

Sounds like a modeling issue maybe more appropriate for the forums at onebuilding.org.

Hi, That issue occurs now in our project too. We have a heated-only production hall and warehouse with the supply air flow 150,000 cfm and 14,000 cfm. The System 11 per 90.1-2007 Addendum dn has a very low SFP (0.3W/cfm). If we simulate the baseline system with system 11, the proposed building fan power is about 2x higher than the calculated baseline fan power. I tried to find some information or suggestion at onebuilding.org, but unfortunately I don’t have found anything about this problem. Is that allowed to use another system type per 90.1-2007 (e.g.System7) and set the cooling coil ‘no duty’ or a higher upper limit of the room temperature that will never reached. Many thanks in advance!

You are not required to use the heating only systems. You can get around the requirement for installing a cooling system by citing the fact that you can simply set the temperatures so that the cooling system would never operate. So you can actually model it that way with a cooling system but this is really a waste of time. We have had success simply explaining that we have not modeled a cooling system because we could set the temperatures high enough that it would not operate and achieve the same effect without modeling the cooling system at all.