Hello,

I've been trying to understand how ERV works because I am finding the energy savings to be somewhat less than I had expected. Ottawa has a very cold climate in the winter and a warm, humid climate in the summer and I would expect enthalpy wheels to be a very good energy saving strategy. Instead, I am finding that in many cases the building uses more energy and in the best case scenario (OA exhaust DH, mixed air reset, modulate HX) on a VAV system saves only 0.15%. I have built a simple box model with one system in a two-storey office building and tried a number of different control strategies (see attached tables for results). I have tried a VAV and a SZ system. The ERV is able to save marginally more energy in the SZ system, but in neither case are the results what I was expecting.

My question is this: are these results to be taken at face value and believed or is there a better way to model ERVs in a Canadian climate? It seems very unlikely to me that ERVs cannot be controlled in such a way as to save significant energy in a climate of extremes. (.inp file attached as well).

With thanks and best wishes,

Daniel Knapp, PhD, LEED? AP O+M