[Equest-users] eQuest - outside air heating issues

[David Bastow]

If you are entering the min. OSA intake through the air handler or
system level then you need to zero out the OSA items in the zone level
to get the system OSA control to work, the only exception to this is if
you are doing something with demand control ventilation.  This will
bring in the min. OSA through the air handler whenever the the air
handler fan is on, unless you set up a schedule to vary the min. %
amount of outside air that is to be brought in through the air handler
at different times.  Anything that you set up for OSA at the zone level
will override what you put in through the system.  The eQUEST program is
set up to automatically do this override  If your air handler was set up
to cycle off at night when unoccupied or you had some schedule to vary
the outside air intake through the air handler, then the amount of OSA
with the system method would be reduced at times.  While, unless you set
up some schedule, the zone level OSA method would continue to bring in
OSA, thus increasing the heating gas consumption.  While there are many
factors on a program this complex that could be causing this gas
increase to happen, I would guess that it is this or something related
to this, as I have experienced this in the past.
 
David A. Bastow 
McClure Engineering, Inc.  

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
Tomlinson, Scott
Sent: Wednesday, May 26, 2010 7:35 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] eQuest - outside air heating issues



Hello all,

 

I have a question regarding outside air input.  For my design building I
enter my outside air at the system level, as the minimum outside air
ratio, which I get from my equipment schedules.  90.1 requires that the
outside airflow be the same.  To do this I take my summary report from
my design building and enter the values from that report into the
baseline model zones.  When I run my baseline model the outside airflow
rates from the summary report match those of my design model, and my
unmet heating hours are good in both models, but the heating gas
consumption in my baseline building triples.  The result is I am getting
great, but unrealistic, energy savings.

 

Does anyone know why this is happening?  Why would entering the OA at
the zone level cause such increased heating for the save total CFM
entered at the system level?  How are you folks typically handling your
outside ventilation air.

 

Any help would be greatly appreciated, thank you.

 

__________________________________________

Scott Tomlinson, PE, LEED-AP

Mechanical

Symmes Maini & McKee Associates, Inc.

1000 Massachusetts Avenue, Cambridge, MA 02138

t: 617.520.9438

 

 

f: 617.354.5758

stomlinson at smma.com <mailto:STomlinson at smma.com> 

www.smma.com <http://www.smma.com/> 

 

 

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