[Equest-users] Demand Controlled Ventilation

[David Frank]

James,

 

In the past I've revised the minimum flow schedule within the thermal zones
and used a ratio of 0 during unoccupied hours to make sure no OSA is being
introduced and -999 ratio for hours of occupancy.  I also do the same for
HVAC system.  Then within the HVAC system I change the minimum OA Method to
DCV return or zonal sensors.  I think the trick is making sure the thermal
zones and HVAC systems operate on the same minimum air schedule that you
specify.  Hope this helps.

 

David Frank

EMP2, Inc.

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Tuesday, November 04, 2008 9:08 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Demand Controlled Ventilation

 

I would appreciate anyone's input on this as well.  I have run 4 or 5 models
recently with DCV, and the results have almost always been either a wash, or
INCREASED energy for DCV.  Most of them are PIU systems with either parallel
or series VAV boxes.  Have used both return air sensors, zone sensors, as
well as both options for calculating the OA quantities.  I think I'm missing
something as well.and I get the same results with increased space cooling in
the winter, as well as increased heating costs.  I think it must be how I'm
defining the zone / system outside airflow rates, but I can't figure it out.

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

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

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Colleen
Nelson
Sent: Tuesday, November 04, 2008 10:12 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Demand Controlled Ventilation

 

I have created a model with DCV as a parametric run and the results are
suspect.  Comparing results for baseline and parametric run, there is
increased space cooling in the DCV model between November-March.  Also,
ventilation fans are running much more during these same months than in the
summer.  And, there are many hours where heating load is not being met.
Both models include economizer control limited by drybulb at 65 F.

 

I've attached .pd2 and .inp files.

 

I appreciate any help on this.

 

Thanks,

 

 

Colleen Nelson, LEED-AP

Mechanical Engineering

Michaud Cooley Erickson

612.673.6995

 

 

 

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