How to utilize zone exhaust air for heatpump water heaters ?

Modeliing a premise with very high internal heat gains such as a data center, it looks reasonable to utilize the zone(s) warm exhaust air with air-to-water heat pumps for producing hot water and simultaneously cooling the air in the airloop. While IDF Editor allows inserting an air-to-water heatpump water heater into the airloop, EnergyPlus however identifies this as "invalid component" in the airloop.

Are there any good alternatives in OpenStudio or EnergyPlus to solve this problem ?

You should set the Inlet Air Configuration to ZoneAirOnly. The HPWH will affect the heat balance of the zone. As long as you also have an AirLoopHVAC supplying and retrieving air from the zone, the impact of the HPWH on the air condition of the AirLoopHVAC should be taken into account.

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Julien Marrec

answered 2018-06-18 07:51:48 -0500

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This solution is OK if the HPWH has to deal with only one zone. In order to use it as an air cooling device, it is necessary to set Minimum Inlet Air Temperature for Compressor Operation to the desired Cooling Setpoint Temperature.

OS-user-AT (2018-06-20 11:28:02 -0500) edit

Good point! I didn't really think about the case where there are several zones. Currently the HPWH is a Zonal object, so you'd have to some EMS magic to propagate HPWH effect onto an AirLoopHVAC Demand Outlet Node or something...