Re: [EnergyPlus_Support] Two AirloopHVAC serving the same zones

On Tue, Jul 12, 2011 at 1:53 PM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

I think I may have known that what Karen suggests is possible, but never actually considered that approach. Great suggestion!

The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Martin Gogov
Sent: Tuesday, July 12, 2011 12:13 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Two AirloopHVAC serving the same zones

Thank you so much for this idea, Karen! I didn't know that!

I think this scenario might work if it is possible to assign different fan types and ADUs to each main branch of the Air loop since I need constant air volume for the ventilation and variable air volume for the cooling.

Could I kindly ask you to give me a short IDF example how to set two branches on the same loop? I'm struggling to find one in the example files..

Thanks!
Martin
On Tue, Jul 12, 2011 at 5:34 PM, Karen Walkerman <kwalkerman@xxxxxxxxx> wrote:

Is there any way to add the packaged VAV with Reheat to your existing outdoor air system airloop? You can't have two airloops, but the airloop itself can have more than one main supply branch, and unlike a plantloop can have more than one outlet node and zone distribution. You could set up one branch of the airloop with the as-designed outdoor air system serving your terminal boxes in the zones, and another branch of the airloop (with a separate exit node) serving a different terminal reheat box.

Good luck!

--
Karen

On Tue, Jul 12, 2011 at 11:10 AM, Martin Gogov <mgogov@xxxxxxxxx> wrote:

Dear EnergyPlus experts,

I'm preparing a model for LEED for a building with multiple zones which has ventilation system for fresh air and a separate heating system.

By design, there's no cooling system in the building.

I've used a single AirLoopHVAC to model the system for fresh air since it serves more than one zones.

I think that the ERV and Outdoor Air Unit systems are not applicable for my case since this would be a major difference with the project docs.

Since by design the building doesn't have a cooling system, it's necessary that in the Proposed and Baseline cooling systems are the same: a Packaged VAV with Reheat.

And here is the problem!

In order to model a Packaged VAV with Reheat, I need to use one more AirLoopHVAC, correct?
This shouldn't work since each zone has only a single Return Air Node and in the zones which have a ventilation system for fresh air, this Return Air Node is already used by its AirLoopHVAC!

And I don't know how to handle Two AirloopHVAC serving the same zones...

I've already spent a few days on this problem but yet I cannot find of a suitable solution.
Any ideas on how to proceed greatly appreciated!

Thank you very much,
Martin