Hello all,

I am working on a model for a LEED submission. The location is a very cold climate (northern Minnesota) and thus relies on radiant floor and FTR to handle envelope load heating (with water to water heat pump), with airside heat pump units only functioning to heat air to the space temperature. Using the proper corrections for a DOAS, outside air, etc., modeling the proposed case has not been a problem.

Appendix G says that I should select system 4 - PSZ-HP as my baseline. If I want to heat using only the airside system, the cooling design flow is actually less than the heating design flow for exterior zones because of the extremely cold climate. Should I keep the design heating and cooling flows the same as in the proposed case and just use electric baseboards to make up the envelope heating difference, or should I bump up the airflows to whatever they need to be and let the airside system do all of the heating?

Thanks in advance,

Todd Lagus, EIT