[Equest-users] DCV-RETURN-SENSOR, Hourly zone OA CFM for SCV Calculation

Holt Cutler HCutler at EMEGroup.com
Wed Mar 14 06:24:32 PDT 2012


Hi Molly,

Based on what you describe, you have your eyes on all of the DCV toggles in eQUEST. One thing that you didn't mention though was the type of system you're modeling. In my experience, applying DCV to some system types results in hourly OA flow that's not responding to your OA-FLOW/PER and OA-FLOW/AREA inputs and occupancy levels. In a recent project, I had DCV operating correctly in a VAV system and a Single Zone Reheat system. Try changing your system to either of those types as a sanity check. Then if it makes sense, go ahead and model your system with that system type. DCV can have a significant impact on your space heating and space cooling, so it is important to get the OA flow sorted out and verified in the hourly report as you are doing.

Good luck!

Holt Cutler, EIT, LEED AP BD+C

[Description: Logo 2]
EME Consulting Engineering Group, LLC
159 West 25th Street, 5th Floor
New York, NY 10001
tel:  212-529-5969
www.EMEgroup.com<http://www.emegroup.com/>


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Molly Curtz
Sent: Tuesday, March 13, 2012 5:19 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] DCV-RETURN-SENSOR, Hourly zone OA CFM for SCV Calculation

Hi All,
I'm modeling a system with DCV set to "DCV-RETURN-SENSOR." The help file says: "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."

However, when I look at the hourly report for the zone, "Hourly zone OA CFM requirement for DCV calculation (cfm)" (Var 100), the CFM does not increase for high occupancy hours. My hand calculations show that when I multiply the OA-CFM/PER by the hourly occupancy, it should exceed the minimum OA ventilation rate for the zone (which I specified using  OA-FLOW/AREA.)

I have set the zone minimum flow ratios to "DCV-RESET-UP/DOWN" and the zone minimum flow is increasing according to the occupancy.

Why is the zone OA CFM requirement not increasing with occupancy? Any thoughts are appreciated.

Thanks very much.

Kind regards,
Molly



Molly Curtz
Mechanical Engineer

Arup
403 Columbia Street  Suite 220 Seattle WA 98104
t +1 206 749 9674  d +1 206 493 2234
f +1 206 749 0665
www.arup.com<http://www.arup.com>

____________________________________________________________
Electronic mail messages entering and leaving Arup  business
systems are scanned for acceptability of content and viruses
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120314/5d6e098e/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 1822 bytes
Desc: image001.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120314/5d6e098e/attachment-0002.jpg>


More information about the Equest-users mailing list