[Equest-users] Demand Controlled Ventilation

[Victor Yeung]

Otto,

 

Thanks for the reply.  The problem I see with dividing the total OA cfm
by the number of people and inputting that number into OA-FLOW/PER is
that this method doesn't address the space cfm requirement.  For
example, if the building is only 10% occupied at a particular hour, then
the OA supplied will be 10% occupant requirement and 10% of space
requirement, not 10% occupant and 100% area as it should be.

 

Victor

 

From: Otto Schwieterman [mailto:oschwieterman at fhai.com] 
Sent: April 28, 2010 1:44 PM
To: Victor Yeung
Subject: RE: [Equest-users] Demand Controlled Ventilation

 

Victor,

 

If you do not have DCV, you must specify the amount of CFM per room (or
per SF) because if you simply put CFM/person, you are essentially using
DCV due to the occupancy change in the schedules. 

 

If you want to utilize DCV, I would calculate the total outside air CFM
required and divide the total by the number of people and input that
number into OA-FLOW/PER.

 

Otto

 

From: Victor Yeung [mailto:Victor at invirosystems.ca] 
Sent: Wednesday, April 28, 2010 12:30 PM
To: Bishop, Bill; Rob Hudson
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Demand Controlled Ventilation

 

Hello all,

 

I also have a similar question related to minimum OA settings for DCV,
particularly with OA-FLOW/PER and OA-FLOW/AREA.  Say I am using ASHRAE
62.1 for my OA rates, there are minimum requirements for cfm/person and
cfm/area.  However, the way eQuest calculates min zone OA is by taking
the higher value of either OA-FLOW/PER or OA-FLOW/AREA, not the combine
total.  To correctly model the OA requirement, I have to calculate the
combine OA rate (i.e. {[cfm/per * max # of person] + [cfm/area * floor
area] } / floor area) and input that value in OA-FLOW/AREA.  Now, the
problem comes in when we include DCV into the model, at which eQuest
cannot calculate the savings because the OA-FLOW/PER value is not
entered.  I would greatly appreciate it if anyone can clarify this.

 

VICTOR YEUNG, BASc, LEED(r) AP

EIT - LEED(r)/Sustainable Development

victor at invirosystems.ca <mailto:victor at invirosystems..ca> 

 

 

From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
Sent: April 28, 2010 11:16 AM
To: Rob Hudson
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Demand Controlled Ventilation

 

Rob,

 

You need to set up an hourly report. See attached.

 

Bill

 

________________________________

From: Rob Hudson [mailto:rdh4176 at gmail.com] 
Sent: Wednesday, April 28, 2010 11:06 AM
To: Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Demand Controlled Ventilation

 

How can i tell if the system is using a lower OA CFM during the less
occupied times? 

On Wed, Apr 28, 2010 at 10:43 AM, Bishop, Bill
<wbishop at pathfinder-ea.com> wrote:

Rob,

 

I recently modeled DCV successfully for the first time. (I showed
savings anyway.) You need to enter zone-level OA as OA-FLOW/PER and/or
OA-FLOW/AREA. The OA flow/per (person) is what will get you the savings,
based on your occupancy schedule(s). I also created a MIN-AIR-SCH,
coinciding with the fan schedule, set to zero when fan is off and -999
when fan is on.

 

Regards,

Bill

 

William Bishop, EIT, BEMP, LEED(r) AP | Pathfinder Engineers &
Architects LLP

Mechanical Engineer

 

134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005

wbishop at pathfinder-ea.com

www..pathfinder-ea.com <http://www.pathfinder-ea.com> 

P Please strive to live sustainably.

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Rob
Hudson
Sent: Wednesday, April 28, 2010 9:55 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Demand Controlled Ventilation

 

I am having some trouble with setting up DCV in my model.  if i select
DCV in Zone Sensors for the Min OA Control Method and a min outside Air
Ratio, do i need any Zone level OA inputs?
Any help or insight as to what inputs are necessary for DCV would be
great!

-- 
Rob Hudson




-- 
Rob Hudson

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