[bldg-sim] VAV vs. Constant volume cooling energy

[Mike Roberts]

Anna,

A PSZ (Packaged Single Zone) system is constant volume, but only has to cool
when the space calls for cooling.  A VAVS system cools the air all the time
(or may use an economizer part of the time), then reheats the air to the
temperature the space requires.  You can improve on this by resetting the
cold deck temperature, but will probably not get your cooling below a single
zone system.  For comparison, try a RHFS system.  That is a constant volume
system, but cools all the air, then reheats it to satisfy the zone.  It will
generally use more cooling than the VAVS system.

Both DOE-2.1 and DOE-2.2 have some fairly extensive documentation on
controls, related to how the programs control real world systems.

Mike

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com]On Behalf Of Zhou, Anna
Sent: Monday, April 12, 2004 6:34 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] VAV vs. Constant volumn cooling energy


The simulation software was DOE2.2.

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com]On Behalf Of Zhou, Anna
Sent: Monday, April 12, 2004 3:19 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] VAV vs. Constant volumn cooling energy


Hi,There

When doing simulation, I noticed that the cooling energy consumption from a
variable air volumn system (VAV,PVAVS) is always larger than that of a
constant volume system (PSZ). Did anybody have this problem, too? Can
anybody tell me what's the possible cause of this?

Thanks a lot.

Anna

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