Open Loop System Energy Modeling

[jchung]

I am wondering if there is anyone who's familiar with IES Virtual Environment that could help me out. I need to model the energy use of a chilled floor cooling system. The system is pumping ground water through a heat exchanger and distributing the "chilled" water throughout the building's chilled floor. I am not sure how to properly simulate the pumps energy usage. Has anyone tried to do this before or know how I should proceed? Thanks.

 

[GMcD]

Use these keywords in a google search:

slab pump control olesen

There are a few papers by Bjarne Olesen on thermoactive slab pump controls. The fundamental starting point is an understanding of the thermal mass and cycle/response times of the active slab. One can run the pumps constantly and modulate the water temperature going into the slab in response to a slab temperature setpoint, or, one can cycle the slab pump (and source cooling pump) based on a dead-band setpoint around the desired slab temperature setpoint (preferred).

The one thing you must make sure of is to NOT use space temperature to "control" the slab - the response time of the slab vs the controls will not work. Ideally, the slab temperature should be set up as a monthly schedule based on average local climate and heating/cooling load profiles. Then use the ventilation air system as the "quick response" local room temperature control function.

Due to the slow response time of the slab, it is essential that a high performance perimeter building envelope be used to minimize the thermal loads and levels of peak transients. If you have a crappy envelope, you'll be forced into using the slab for the steady state interior zones and use some kind of perimeter HVAC system that can deal with high/fast acting transient loads imposed by the envelope.