Is there a way to schedule maximum zone airflow in eQuest?

asked 2015-08-19 11:17:05 -0600

jkjenner

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updated 2015-11-12 16:09:06 -0600

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

I'm attempting to model in eQuest a school that uses a simplified method of DCV.

In each classroom there is a vacancy sensor that, if it does not detect motion for a set period of time, generates a signal that is used to both turn off the lights in the classroom and also shut its supply air damper.

I'm wondering: is there some sort of method that can be used to schedule zone-level airflow that I could use to model this? What I'd like to do is simply schedule these dampers to close during the school's unoccupied hours. I see that eQuest/DOE has the ability to schedule minimum airflow at the zone level, but really what I need is the ability to schedule the maximum airflow.

Any help would be much appreciated. I'd also be open to other approaches to modelling this.

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answered 2015-08-19 12:41:06 -0600

Chris Jones
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The MIN-FLOW-SCH specifies an hourly schedule - a value between 1 (maximum flow specified) and 0 (no flow). This schedule controls the supply flow at the ZONE level.

You can think of it as the maximum flow available if that helps.

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To be honest I was a bit bewildered by this answer as I couldn't understand how my perspective would affect the simulation... but I tried it, and it worked! So thanks for your help! That said, it still doesn't really make sense to me; the name of the field ("MIN-FLOW-SCH") and documentation seem to suggest that this schedule sets a minimum supply air value--i.e. one that could theoretically be exceeded if necessary--but during the hours when I put the minimum to 0, no supply air will flow, even as the zone temperature falls well below its setpoint. Do you have a sense of why this might be?

jkjenner ( 2015-08-20 10:19:46 -0600 )edit

MIN-FLOW-SCH is intended to modulate the zone supply air flow for each hour. The values in each hour are the fraction of the specified supply air flow rate. Therefore, 0 means no flow for that hour. The program will not override that value to meet the zone loads. This is the intended behaviour.

Chris Jones ( 2015-08-20 12:09:42 -0600 )edit

Weird. If the rate can't be exceeded, "minimum" seems like a bit of a misnomer. In any case thanks for your help and answer.

jkjenner ( 2015-08-27 17:05:01 -0600 )edit

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answered 2015-08-19 13:34:09 -0600

Rohini
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I think you will have to set the min flow sch at the zone level to 0 for these times, make the thermostat setpoints for these times to be outside the heating/cooling range (so that heating/cooling is not needed). I also think the outside air to this zone should be zero at these times, since the min flow is decided by the outside air also - but I am not sure on this - you will have to test it out. -Rohini

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Now I recollect - if you need the OA to be zero for a certain time period, you should change the occupancy to zero for that time, and use the OA/person keyword for entering OA data. Also check the keywords for DCV - you might have to use them to get the supply to zero.

Rohini ( 2015-08-19 15:29:23 -0600 )edit

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