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How to model GSHP with radiant floor heating in OpenStudio?

asked 2015-04-30 17:36:53 -0500

Jlove gravatar image

updated 2018-10-19 09:01:55 -0500

BORM gravatar image

I design a small house, using OpenStudio 1.7.2, with a ground source heat pump (GSHP) for space heating, cooling, and hot water use. But I've got a serious trouble in modeling HVAC. Overall scheme is like this:

(1) the main system is GSHP (2) space conditioning is supplied by underfloor radiant heating and cooled air from a terminal unit mounted on the ceiling. That is, water heated by GSHP circulates underfloor tubes, and chilled water coil exchanges heat with outdoor air to cool the air during summer.

I think water-to-water GSHP is desirable for heating, and water-to-air for cooling. However, I have no idea of how to combine those water-based loop and air loop to support for a single thermal zone. Please let me know if you possibly know how to construct GSHP with radiant floor heating without implementing "district heating or cooling" plant object.


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answered 2015-04-30 18:45:27 -0500

updated 2015-04-30 23:06:50 -0500

Welcome @Jlove. Here are some resources to get you started with a GSHP plant loop serving radiant zone systems.

GSHP Plant Loop: Vertical Ground Heat Exchanger sizing with GLHEPro (OpenStudio Documentation)

Radiant Zone Systems:


I just ran a model successfully with the following GSHP loop configuration serving WSHPs in the zones. The only change I made was to the plant loop type (condenser), the rest of the inputs are defaults and may need to be changed depending on your specific use. You also may want to consider a bypass on either the supply or demand side by adding an adiabatic pipe to the respective drop zone.

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Thanks so much, Matthew. I appreciate your quick response and detailed illustration. The tutorial you linked was so helpful that I could model GSHP, GLHEPro seems not for free though. However, there still remains a problem, like plugging radiant heating system into the WSHP. It seems to me yours also doesn't look like low temp radiant heating/cooling. A tutorial for radiant conditioning suggests to use HW boiler as a supply equipment. That said, I thought WSHP could also make sense, and attempted to connect the radiant equipment to WSGP, but heat/cooling load resulted in blank....

Jlove gravatar imageJlove ( 2015-04-30 22:51:37 -0500 )edit

I'm not sure you'll be able to successfully run a model with a condenser loop connected to hydronic systems. I've typically seen these connected to zone heat pumps, do you have a particular design that specifies this configuration? . You could try building the radiant system using the link I provided above and then connect it to the condenser loop. However, if the model runs successfully the HVAC system may not be capable of heating/cooling adequately due to the relatively steady condenser water loop temperatures which are typically 80-90F.

MatthewSteen gravatar imageMatthewSteen ( 2015-05-01 00:25:19 -0500 )edit

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Asked: 2015-04-30 17:36:53 -0500

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Last updated: Oct 19 '18