[Equest-users] EE4/DOE 2.1e - VAV using 100% outdoor air

[Robin Thornton]

Hello all,

Since EE4 is really a front end for DOE 2.1e, I thought I should pose my question here:

What's the best way to model a 100% OA VAV system in DOE 2.1e?

We frequently need to model laboratories with fume hoods for LEED, which use 100% OA built-up VAV systems with exhaust heat recovery. EE4 does not handle VAV systems with 100% OA. A workaround we have used in the past is to establish a weighted average of the occupied/unoccupied air change rates, and input this value as the required OA. Then we use this same value as the minimum and maximum VAV terminal airflows. Of course, this turns the VAV into a CV system, which does not allow us to take credit for fan VFDs and limits the range of free cooling.

Any suggestions would be appreciated regarding functions or keywords I could implement in DOE to tell the VAV to use 100% OA while still allowing the VAV boxes to modulate. Using an example of a system requiring 4 OACH unoccupied, 10 OACH occupied, I've been experimenting with using MIN-AIR-SCH to schedule the OA (SCH = 0.4 unoccupied, 1.0 occupied), and would like to know if I'm on the right track.

Thanks in advance for your help.

Robin Thornton

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130417/03606947/attachment.htm>