[Bldg-sim] LEED and CO2 DVC

[Nick Caton]

eQuest can model demand-control ventilation in a few ways, without you
having to define a custom schedule.  There are two options for
MIN-OA-CONTROL... everything is do-able through the detailed interface
(maybe the wizards too, can't recall), without jumping into the .inp
file.

 

Following is a copy/paste from the DOE2 help file giving the full
behavioral explanation:

 

DCV-RETURN-SENSOR This codeword instructs the program to model a DCV
device that uses a CO2 differential between the SYSTEM return air stream
and OA intake air stream to determine the hourly minimum OA fraction.
The program calculates the OA minimum requirement and sets the minimum
damper position hourly based upon the sum of the ZONE requirements. Each
zone OA requirement is calculated based upon the hourly maximum of
either OA-CFM/PER (times the NUMBER-OF-PEOPLE adjusted by the hourly
PEOPLE-SCHEDULE) or a minimum OA ventilation rate. The zone minimum OA
ventilation rate is either MIN-OUTSIDE-AIR if specified or the maximum
of OA-CHANGES (times the zone VOLUME/60), OA-FLOW/AREA (times the zone
AREA.)

 

DCV-ZONE-SENSORS   This codeword instructs the program to model a DCV
device that uses the highest CO2 differential between the each ZONE air
and OA intake air stream to determine the hourly minimum OA fraction.
The program calculates the OA minimum requirement and sets the minimum
damper position hourly using the "critical" zone requirement; the
critical zone requirement is defined as the zone having the highest
fraction of OA relative to its hourly supply air flow rate. Each zone OA
requirement is calculated based upon the hourly maximum of either
OA-CFM/PER (times the NUMBER-OF-PEOPLE adjusted by the hourly
PEOPLE-SCHEDULE) or a minimum OA ventilation rate. The zone minimum OA
ventilation rate is either MIN-OUTSIDE-AIR if specified or the maximum
of OA-CHANGES (times the zone VOLUME/60), OA-FLOW/AREA (times the zone
AREA.). The value of the zone minimum OA ventilation flow rate is
divided by the specified/calculated zone supply flow to calculate hourly
zone OA fraction; the zone with the highest hourly flow fraction value
is the "critical" zone.  Setting the sum of the ZONE OA flow
requirements divided by the system total supply fan flow to X, and
letting the critical zone OA fraction be denoted as Z, the system hourly
minimum OA flow fraction is then X/(1+X-Z)

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Jones
Sent: Wednesday, November 04, 2009 1:43 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] LEED and CO2 DVC

 

Is there a generally acceptable way to model CO2 demand ventilation 

control for a LEED C&S project?

 

On other LEED projects (not Core & Shell), I have used the occupancy 

schedule to set the outdoor air flow.

 

 

 

 

Chris Jones

14 Oneida Avenue

Toronto, ON M5J 2E3.

Tel.  416-203-7465

Fax. 416-946-1005

 

 

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