Cascading airflows in eQUEST

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Is it possible to cascade airflow from one zone to another in eQUEST? I'm familiar with the OA from system function. Is there an OA from Zone command? I have a situation where we have significant makeup air from one zone coming into another.

Vikram Sami
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vsami's picture
Joined: 2013-05-31
Reputation: 1

Hi Vik, no you can't. DOE2 is a static calculation and cannot exchange from zone to zone. The only way I can consider to try to mimic something would be to use one large zone for both and then reduce the amount of air changes in that zone compared to a normal input; and then try to widen the t-stat range for a lower load in that zone so it acts more 'neutraly' conditioned than a typical HVAC approach. Otherwise if you figure something out id like to learn what you did.

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Pasha Korber-Gonzalez's picture
Joined: 2011-09-30
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This is just a suggestion and I haven't had time to investigate it yet, but I would think that the zone that the air is cascaded to could be represented by a PSZ system that uses the specified amount of zone transfer supply air with supply heating and cooling temperatures around 65 F heating and 75 F cooling and heating and cooling devices that are artificially constructed so they don't consume energy since you have already paid for the energy in the first zone. Its not perfect, but it might be close enough.

Kathryn Kerns's picture
Joined: 2011-09-30
Reputation: 0

I usually just model the two zones with an air wall in between them, and split the supply CFM between the zones (not necessarily evenly - you would favor the transfer-from zone as it would have conditioning priority). I also use different thermostat schedules for the transfer-to zone (as applicable) as it is usually designed to float more than the transfer-from zone. Both zones would be assigned to whatever system supplies the air to the transfer-from zone.


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Bill Bishop's picture
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I agree with the suggestions below. As long as the transfer air is at room temperature and there are no significant heat loads in the downstream space, I don't think it makes much difference where the air is exhausted as long it is from a zone in the same system. Remember that we are not modeling the building, we are modeling the energy use of the building. Keeping this in mind can often simplify our work.

I often make the air go in and out of the same zone whenever possible. For example, if I'm transferring air from a corridor to restrooms I would either

1. Combine the corridor and restroom as a single zone, or

2. Assign outside air and exhaust air to the corridor only, or

3. Assign outside air and exhaust air to the restroom only, or

4. Divide the outside air and exhaust air proportionately between the corridor and the restroom.

By the way, Trane TRACE and other programs can model transfer air from one space to another.

Keith Swartz, PE, BEMP, LEED AP
Senior Energy Engineer | Energy Center of Wisconsin | Madison.Chicago.Minneapolis
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