I am working on a LEED model for a fully designed building. The model
attempts to incorporate a ground-source heat pump system (modeled as a
Lake/Well loop with temp schedule) with water-to-water heat pumps
(chiller type = heat pump) serving a dual temp loop going to active
chilled beam (induction unit system) zone conditioning. Zones on this
system have envelope loads covered by baseboard heaters on a separate
boiler loop. The baseboard loop is scheduled to be available from
September through May, while the dual temp loop is set to "snap" between
heat/cool at 58oF OA. The design intention is for the water-to-water
heat pumps to provide all outside air conditioning for this system -
first tempering to neutral at the system level, and then further
conditioning at the zone level.

During much of the winter, even when the building is occupied and zones
are receiving outside air, heat pump operation is very low. GSHP loop
flows are inconsistent day-to-day during most of the winter. When I try
different weather locations, the profile of heat pump operation varies
significantly, but electric heating energy and GSHP loop flow remains
low.

Why do I see erratic heat pump operation and loop flows?

I realize this is a complex model and not an easy question to dive into,
but I would appreciate it if anyone has any advice from experience with
a similar model. I can attach model files if that would help.

Thanks,

Eric

Eric Boxer, EIT