[Equest-users] eQuest Accounting for Exhaust Fan Energy for LEED

[Anthony Hardman]

I've run into the same problem too.  One thing I've tried is to decrease the
zone level EA cfm until the unmet hours are reasonable, and then increase
the kw/cfm the commensurate amount.  That way, at least there's some zone
level exhaust airflow and the SV-A report shows EA fan power equal to what
is on the exhaust fan schedule.  A narrative to the GBCI reviewer explaining
the simulation limitations would hopefully suffice.  

 

Anthony Hardman, PE

LEED AP BD&C

Building Performance Analyst

 

THE GREEN ENGINEER, LLP

Sustainable Design Consulting - Energy Modeling - LEED Project Management 

50 Beharrell St

Concord, MA 01742

O: 978/610-2801

C: 720/840-7862

 

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From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Seun
Odukomaiya
Sent: Wednesday, June 22, 2011 8:15 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] eQuest Accounting for Exhaust Fan Energy for LEED

 

eQuesters

 

I'm having some difficulty with properly modeling exhaust fans in for LEED
and I'm hoping someone can provide me with some guidance. 

 

Here's my problem: I can enter the exhaust volumes and associated KW/cfm for
each zone where necessary, but some of the spaces have design exhaust
volumes greater than design supply air volumes (negative pressure rooms). If
I select "infiltration" or "balanced infiltration" as the source of exhaust
makeup for these zones, then the unmet hours for that zone become very high.
If I select "air handler" as the source of makeup air, then eQuest increases
the design supply air volume to match the exhaust air volume for that zone.
This is problematic because the SV-A reports now have values that do not
match my mechanical schedules. Additionally, the energy consumption
associated with those systems increases as a result of the increased supply
air volume. All in all, it's just not an accurate representation of the
design. Most of these zones are expected to make up the air through zonal
air transfer (something I realize eQuest is unable to do).

 

At this point, I'm considering adding the exhaust energy as a direct load to
my meter along with appropriate usage schedules, and associating it to
"ventilation fans". I believe the net effect on energy consumption and peak
demand should be the same as if the exhaust fans were explicitly modeled.
However, I'm curious as to any dynamic system or thermal effects that I may
be circumventing by not explicitly modeling the exhaust fans for each zone.
My gut feeling is that there shouldn't be much of an effect, but I'm just
not sure. I'm also concerned that by modeling exhaust energy as a direct
load, rather than explicitly, the SV-A reports won't show any exhaust
volumes and thereby call attention as to the validity of the model.

 

At this point, I would like the guidance of some of the members on this
forum that have more experience with these issues. Is this even an
acceptable way to account for exhaust fan energy for LEED? I'm open to any
suggestions from anyone who has run into these issues and/or may have
experience in how to deal with it.

 

Thanks in advance

 

Seun Odukomaiya, EIT, LEED AP | Mechanical Engineer | L'Acquis Consulting
Engineers |(317) 706-2075 Ext. 255 |  <http://www.laceindy.com/>
www.lacquis.com | To transmit large files, please use:
<http://lacquis.leapfile.net/> http://lacquis.leapfile.net

 

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