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[BLDG-SIM] : eQuest Underfloor Air



Hello Kendra,
 
The following is a link to a blog I've started with the intent to eventually collect all the arcane but useful scraps information necessary to do these energy analyses efficiently:
 
http://elcca-exchange.blogspot.com/2006/08/equest-displacement-ventilation.html
 
There's link within this to an Energy Designed Resources paper that I used (Which another kind user in turn had pointed me to) to set up my prototype displacement ventilation system.  While doing so I also found the screenshot in eQuest 3.6 that shows the 'lighting heat to return air or adjacent space' (i.e. plenum) option that the EDR paper does not mention. 
 
Assigning the stratified heat fraction using this screen may prove useful in solving your problem... but I can't state that definitively has I haven't had the chance to really test it out. 
 
If this does indeed solve your problem and you have a moment, please let me know... I'll be getting back the simulation business soon enough.
 
Brandon
 
 


From: BLDG-SIM@xxxxxxxx [mailto:BLDG-SIM@xxxxxxxx] On Behalf Of Tupper, Kendra
Sent: Monday, September 18, 2006 3:26 PM
To: BLDG-SIM@xxxxxxxx
Cc: kevinjm5000@xxxxxxxxx
Subject: [BLDG-SIM] : eQuest Underfloor Air

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
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