[Bldg-sim] ASHRAE 90.1-2007 modeling for a Baseline system with humidity control

Jim Dirkes jim at buildingperformanceteam.com
Tue Apr 24 07:09:56 PDT 2012


Dear Forums,

A recent discussion with a colleague has made me question my understanding
of the proper way to model an HVAC system when humidity control is a project
criteria.  Imagine a building in South Florida that requires the space
humidity not to exceed 55% RH. 

1.       The building might use Baseline system #4 (heat pump with electric
supplemental heating).  I have modeled that in the past simply as a normal
heat pump with sub-cool + electric reheat for humidity control.

2.       Another possibility is a System #5 or #6 (VAV fan with VAV or PFP
boxes and reheat). 

 

The question is this:

90.1 has restrictions on the amount  of air that may be reheated (It's the
greater of 0.4 cfm / sq.ft. or 30% of the peak airflow rate plus a few other
items). These are noted in Section 6.5.

Appendix G, however, does not reference the requirements of Section 6.5
anywhere (that I can see).  Do they apply to a Baseline energy model?

 

Thanks for your input!

 

 

Description: BPT BizCard JVDII Updated

Making me think..

Seek truth while you are young, for if you do not, it will later escape your
grasp

 

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