Energy modeling- DOAS units with reactivation air

Matt Hollenbeck

Mechanical Engineer

ARCADIS

LEEDuser Basic Member

0 thumbs up

December 7, 2017

I have an HVAC system that will use a DOAS unit to supply neutral temperature air in a humid climate (climate zone 2). The proposed DOAS unit utilizes a dessicant wheel with reactivation air. Do the reactivation air and reactivation fan need to be explicitly modeled and included? If so, how? I'm using Trane Trace 700 and there is really no acknowledgment of such a thing- just heating or reheat. The main cooling/heating is via hydronic air handler (chilled and hot water).

Post a reply

Matt Hollenbeck

Mechanical Engineer

ARCADIS

LEEDuser Basic Member

0 thumbs up

Thu, 12/07/2017 - 15:33

I should amend this question, as I did find options for dessicant wheel. But is the reactivation air/heating considered a process load or part of the HVAC system energy usage?

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Thu, 12/07/2017 - 16:02

For LEED yes you must include this energy use in your modeling results. The how tends to be very specific to the software you are using. For Trace you should be albe to contact them for help. There is also a Trace Users discussion forum at onebuilding.org where you can post questions. In general if the software you are using cannot explicity and directly model something then you must use a work around. Ideally this work around is recommended by the software developer or has been published and peer reviewed. You must then provide a full description of the work around and why it accurately represents what you are trying to model. 90.1 Appendix G, Section G2.5 addresses the use of work arounds. LEED uses the exceptional calculation method for other issues beside this one too.

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Sat, 12/09/2017 - 19:31

HVAC energy usage in the Proposed only.