Modeling Centralized Water-to-Water HPs with Geothermal HPs using EE4

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I?m using EE4 (Canadian Energy Modeling Software) to model centralized
water-to-water heat pumps system which provides hot/chilled water to make up
air unit heating and cooling coils respectively, there are also distributed
ground source heat pumps in the spaces which are connected to the ground to extract/reject heat. This combination of systems are not
supported in EE4, does anyone know of a work-around to model such system?

I appreciate any input on this ...



Ahmed Azhari2's picture
Joined: 2011-09-30
Reputation: 0

Hi Ahmed,

You can define multiple plants in EE4 - what if you created one plant for
your centralized water-to-water heat pumps and a second plant for your
distributed heat pumps?


bfountain's picture
Joined: 2011-09-30
Reputation: 201

Hi Brian, Thanks for your reply.
This is the scenario; two make up air units provide fresh air into condominium corridors. The heating and cooling coils are fed from water-to-water heat pumps. In each suite, there is a ground source heat pump.
If i follow your suggestion, I create a CombinationGSHP plant with MAU system (perhaps i should choose 2-pipe FCU system) and assign only the zones with the corridors (since fresh air is dumped into corridors).
The second plant would be Geothermal system with a dummy MAU system and assign suite zones under that system. I should set the fresh air quantities to zero in the suites since fresh air has been taken care off in the first plant?
Do you think this is a good presentation of the system?

Ahmed Azhari2's picture
Joined: 2011-09-30
Reputation: 0

You could do that. Given the interaction between the systems through the
OA, I would be inclined to keep them as 1 system. Put the capacities for
the corridor system at the "system level" of your HP system type and then
the distributed heat pumps go at the zone level. Set the system level
heating to hot water and the system level cooling to hydronic - this will be
your corridor system.

At the plant level, I would use an electric boiler to model the
water-to-water heat pump (which is what EE4 does behind the scene anyways
only it uses a EIR < 1 = 1/COP) - you are forced to set the efficiency to 1.
Outside of EE4, simply divide the electrical heating load by a reasonable
heating seasonal COP. Central cooling will be a chiller representing the
cooling from your water-to-water heat pump.

I'm not sure if that is clear - it is Friday afternoon after all.


bfountain's picture
Joined: 2011-09-30
Reputation: 201

See attached screen shot. It's not entirely clear, but it sounds like you select heat pump (normally reserved for air-to-air) and EE4 applies some sort of adjustment to approximate the performance of a water-to-air heat pump. Give it a try and see what EE4 does to the DOE file.


Kyle Fridgen's picture
Joined: 2011-10-02
Reputation: 200

Ahmed, if I understand correctly:
1. There is a ground loop that feeds
water-to-water heat pumps. These heat pumps
provide heating and cooling to the make-up air
systems - both heating and cooling coils in each
unit so there are two loops - the hot water loop and the chilled water loop?

2. There are WSHP units in each suite - the loop
feeding this units comes straight from the
ground? Or is the temperature maintained by the
water-to-water loop after the ground source loop?

The answers will help determine the best way to
model starting with EE4. You may have to finish
the modelling by editing the .DOE file.

Chris Jones's picture
Joined: 2011-09-30
Reputation: 0