[TRNSYS-users] reg: zone voulme and capacitance

[Jeff Thornton]

 "Is there any rules and regulation for feeding those data. "

Just that the volume has to greater than zero.

"Suppose room of size  5x10x5 m (250m^2) is taken , will the zone volume be  equal to room volume for single room or vary on either extremes?."

Typically we set the zone volume to the room volume - that's the easiest and most straightforward thing to do.
 "The same case for capacitance, is there any basic  criteria for selecting capacitance?, eventhough default value  is 1.2xZV."

It depends entirely on the type of zone that you are modeling.  For residential and commercial zones I usually multiply the volume by 10 to 50 times the default value to account for non-wall capacitance.

" will it make major changes in inside temeperature or heat transfer calculation?"

Heat transfer calculation - no.  Inside temperature - yes.  The higher the capacitance the slower the building will respond to changes.  Try different values until the building behaves like you think it should to a step-change in temperature.   "Suppose if there is no furniture inside, what will be capacitance in that case?"

If you account for every interior wall/door etc with walls inside the zone.  And there is no furniture, books, television, paintings, equipment etc. then the value could be set to the default value.  Many times we'll add a "fake" interior wall to mimic the mass effects of furniture and other items.

Jeff

****************************************************************
Jeff W. Thornton
President - Thermal Energy System Specialists
2916 Marketplace Drive - Suite 104
Madison WI 53719
(608) 274-2577 

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