[BLDG-SIM] : eQuest Underfloor Air

[Tupper, Kendra]

I'm trying to use eQuest to compare an Underfloor Air System and
conventional VAV system.  I have modeled the Underfloor case according
to the Addison/Nall paper, and am having some issues with the return air
temperatures. 

 

I have modeled two stratified zones (a lower occupied 5' zone, and an
upper 8' plenum space).  A portion of the internal gains and window
conduction is modeled in the plenum space, and the return air path is
set to PLENUM.  I expected a portion of the cooling loads to be
transferred to the return air, raising the return air temperatures, and
allowed the loads in the occupied zone to be met with a higher supply
air temp (SAT).

 

However, when I increase my SAT for the underfloor case, my cfm and fan
energy increases accordingly.  I output hourly return air temps for the
two cases and found that they were the same - adding heat gains to the
plenum space did not increase the return air temps.  Further, I adjusted
my heating and cooling setpoints for the zones, and found that the
return air temps are equal to these zonal setpoints, regardless of what
load is imposed on the plenum spaces.

 

Has anyone experienced this problem?  

 

Thanks!

 

Kendra

 

Kendra Tupper 
LEED(r) AP                
 FLACK + KURTZ  
405 Howard Street               415.398.3833 Main 
Suite 500                       415.402.5840 Direct 
San Francisco, CA 94105         415.433.5311 Fax 
http://www.flackandkurtz.com    kendra.tupper at sf.fk.com
<mailto:kendra.tupper at sf.fk.com>  
 

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