[Equest-users] Unmet cooling hours

[Charles Land]

For one, I noticed that your outside air fraction for all of your vav systems is 1.  Do none of them have any return?  I see that you specified 20,000 CFM for your MAU but its actually supplying 75,000 because all the vav systems are calling for 100% outside air.  You also specified the MAUs supply flow and the oa cfm for your dummy zone at 20,000 cfm.  I would restore both of these to default and allow the MAU to size itself off of what your vav systems are calling for.  It looks like if you specify the vavs for ~17% oa it will get you in the ballpark of 20,000 CFM through your mau.  You can look at your summary tab to check this.  I would also make your dummy zone smaller. .1 by .1 is what I usually go with so it will call for as little airflow as possible.

But even after reducing the outside air the unmet hours are still there.  Your chillers are too small.  If you let the chillers auto-size, or specify larger capacities,  the unmet cooling hours go away.  That is, before or after, making the adjustments above.

I hope this helps



-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Erik Weiss
Sent: Saturday, November 13, 2010 5:14 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Unmet cooling hours

I seem to be having a problem with unmet cooling hours, the majority of the zones are significantly outside the set points. It seems to be a control issue, if someone can please take a look at my model i would greatly appreciate it.