[Bldg-sim] Large Unmet Heating/Cooling in Baseline

[Michael Rosenberg]

Rob,

You should be modeling one PSZ for each thermal zone.

Mike

Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> "Rob Bialobrzeski" <rbialobrzeski at dmiinc.com> 3/14/2008 12:30 PM >>>

I am modeling a school gymnasium building that has two gyms and a two story office/locker room wing.  The office/locker room wing has several zones that have very different loads, but are designed to all be served by the same packaged, constant volume, 100% outside air ERV.  In the design case model, heating is supplied to these zones primarily by HW baseboards, while cooling loads are satisfied by the supply air.
Appendix G dictates that the baseline HVAC system be Type 3, PSZ-AC with constant volume DX cooling and furnace heating (no reheat).  When modeling this system type, I am getting a large amount of unmet heating and cooling hours (as many as 1,500 hours for a given zone) in the office/locker room zones.  My guess is that this is happening because the baseline HVAC system has no heat source at the zone level (where the proposed case has baseboards), and many of the slave zones have very different heating/cooling loads than the control zone.  I am not sure how I can adjust the model to eliminate these unmet hours while still being consistent with Appendix G.  The only method that has worked for me so far is to drastically increase the system supply flow, but this creates large fan savings that may not be reasonable.  Is it appropriate to add zone reheat even though it is not called for in Appendix G? 
 
Hopefully I’ve presented my problem clearly enough.  Any help would be much appreciated!
 
Thanks,
 
Rob Bialobrzeski
 
DMI
35 Walnut Street
Wellesley, MA 02481
Phone: 781-431-1100 x17
Fax: 781-431-1109
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20080314/7c7e9344/attachment-0002.htm>