[bldg-sim] Fan energy and cooling energy for VAV system

[Paul Riemer]

For air side sizing discussions relevant to App. G, the oversize ratio
(G.3.1.2.2) and delta T (G 3.1.2.8) sections seem to be pretty key.
Paul Riemer

________________________________

From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Renee J.
Azerbegi
Sent: Friday, November 18, 2005 11:07 AM
To: bldg-sim at gard.com
Subject: [bldg-sim] Fan energy and cooling energy for VAV system



I was just having a similar problem using Appendix G. For the proposed
design you are to use the CFM of the design; for the base design you are
supposed to let eQuest autosize with a supply air reset delta T of 10 F.
eQuest still predicts much lower CFMs than the design engineer, so it
results in a net energy penalty. 

Renee

 

________________________________

From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Martin
YIP
Sent: Thursday, November 17, 2005 11:38 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] Fan energy and cooling energy for VAV system

 

Dear Sirs/Madams,

 

I am using eQuest to model an existing office zone with VAV system and
have performed a parametric run with different shading coefficient for
the glazing.  My problem is the large inconsistency when I model the
case with the VAV supply air fan design CFM defined and when I model the
case with the VAV supply air fan design CFM not defined.  For the run
that have the design flow rate defined, the fan energy (SS-L report) and
cooling energy (SS-A report) of the VAV system stays relatively constant
for different parametric scenario.  However, when the supply flow rate
is not defined, the fan energy and cooling energy varies significantly
with different parametric scenario (in which I think it is more
reasonable).  Does anyone have similar experience or comments on the
case.

 

Regards

Martin YIP

 

 
 
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