[Equest-users] Night time setback

David Eldridge DEldridge at grummanbutkus.com
Mon Apr 14 12:33:19 PDT 2014


The setback strategy you are describing sets a minimum airflow, not a maximum. I don’t believe the actual control sequence would limit the ACH to a maximum value – if there was heat gain in the space, the system would ramp up to meet the demand. Because the OR suite is unoccupied, the 6 or 10 ACH requirement should set the requirement instead of cooling load.

Set a report variable to monitor the airflow quantity to verify that the system is behaving the way you expect – if the airflow is limited to a low level according to ACH and not heat gain, then changing the minimum as suggested will model the actual system.

Similarly when the OR is occupied, both ACH and cooling requirements are higher – most likely the airflow will still be limited by the 20 ACH.

David


David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bosch, Crina
Sent: Monday, April 14, 2014 2:06 PM
To: Jeremy McClanathan; 'John Aulbach'; 'equest-users at lists.onebuilding.org'
Subject: Re: [Equest-users] Night time setback

The system is actually a mixed air system with 25% OA.  The zone control is a good idea but I need to set up a maximum flow instead of a minimum. Any thoughts?

Crina Bosch
Designer, Sustainability
karpinski
ENGINEERING
3135 Euclid Avenue
Cleveland, OH  44115
P  216.391.3700 ext 3087
F  216.391.0108
E  cbosch at karpinskieng.com<mailto:cbosch at karpinskieng.com>
W www.karpinskieng.com<http://www.karpinskieng.com>

From: Jeremy McClanathan [mailto:jmcclanathan at CDiengineers.com]
Sent: Monday, April 14, 2014 1:41 PM
To: 'John Aulbach'; Bosch, Crina; 'equest-users at lists.onebuilding.org'
Subject: RE: [Equest-users] Night time setback

If it is a recirc unit, a second option would be to use a zone min flow schedule.
Jeremy

___________________________________________
Jeremy McClanathan, P.E., BEMP, HFDP, LEED® AP
[CDi_Engineers_logo_color.jpg]
19203 36th Avenue W, Suite 200, Lynnwood, WA 98036
P 425-672-1071 | F 425-778-8769
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From: John Aulbach [mailto:jra_sac at yahoo.com]
Sent: Monday, April 14, 2014 10:37 AM
To: Bosch, Crina; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Night time setback

Crina:

If your system is 100% OSA (whicI i believe it is), you can use the MIN-FLOW-SCH to set an hourly air flow(and thus outside airflow) for your space.

John R. Aulbach, PE

From: "Bosch, Crina" <CBosch at karpinskieng.com<mailto:CBosch at karpinskieng.com>>
To: "equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>" <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>>
Sent: Monday, April 14, 2014 10:19 AM
Subject: [Equest-users] Night time setback

I am running a model for an operating room.  My goal is to show the system savings for a night set back.  I am using a VAV system that is currently running 24/7 at 100% flow.  My goal is to show the benefit of running this system at different maximum airflow levels while maintaining constant flow during unoccupied times.

If my OR schedule is 5am to 5pm, I would like the fan to run at 20 ACH during occupied time, 10 ACH during the first 3 hours of unoccupied time, and 6 ACH for the remaining unoccupied time.

Can I achieve this by adjusting fan schedules, or fan parameters for different occupancy settings?  Any advice that may point me in the right direction would be helpful.

If three different levels of fan speed are too much to ask, I would be happy with being able to run at 20 ACH during occ. And 6 ACH during unocc.

Crina Bosch
Designer, Sustainability
karpinski
ENGINEERING
3135 Euclid Avenue
Cleveland, OH  44115
P  216.391.3700 ext 3087
F  216.391.0108
E  cbosch at karpinskieng.com<mailto:cbosch at karpinskieng.com>
W www.karpinskieng.com<http://www.karpinskieng.com/>


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