[Equest-users] eQuest Supply temperature as function of outside air (55°F in summer, 70°F in winter)

Bishop, Bill bbishop at pathfinder-ea.com
Tue Sep 23 06:54:33 PDT 2014

Yes, I’m also curious to hear if anyone else is modeling DOAS using the method I described, and any feedback they might have. (Model the DOAS as a separate system, use the plenums above conditioned zones as additional conditioned zones, assign all OA to the plenums, assign plenums to the DOAS, create air walls between plenums and conditioned zones below.)
I assume DOE-2 puts a system into heating or cooling mode based on the space temperatures and thermostat schedules. For system types with zonal heating capability, I’m guessing system air handlers stay in cooling mode until and unless all zones call for heating, as the air handler can then satisfy zones that need cooling while the zonal reheat and/or baseboards satisfies heating demand. For system types designed for serving multiple zones, there must be code that determines when the mode changes based on number of zones demanding heating vs. cooling. Now that I’m thinking about it, the COOL-CONTROL keyword does this. Now, as for setting the supply air temperature based on OA temperature, you can do this by setting the system COOL-CONTROL to RESET and using a COOL-RESET-SCH. The COOL-CONTROL keyword is not applicable to all system types. Some TYPEs that use it include Induction Unit, Variable Air Volume and Pkgd Var Vol. Some that don’t include PTAC, PSZ, Fan Coil, Water Loop HP and Single Zone Reheat.

From: Julien Marrec [mailto:julien.marrec at gmail.com]
Sent: Tuesday, September 23, 2014 3:49 AM
To: Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] eQuest Supply temperature as function of outside air (55°F in summer, 70°F in winter)

I've read the thread with attention, and it seems like a clever way to model it, one I would certainly consider in the future.
(Here I don't have individual plenum spaces and I'm not planning on redoing my geometry). This thread is from November 2013, so almost a year ago, I'm curious about what people who have been using this method for a while have to say about it?
I guess my problem is even deeper. I really don't see how I'm supposed to be modeling a midpoint or hysteresis controller (such as the ones I attached to my previous email), no matter which type of system I'm using. Can someone enlighten me please? What dictates whether my DOAS is in heating or cooling mode?
Do I have to create a weird heating and cooling schedule manually by looking at my weather file in excel or something?

Also, is there any way to add custom controllers and write your own logic (IF Sensor THEN Actuator...) similar to the EMS in EnergyPlus? If I could write this pseudocode for the midpoint one I'd be ok...
If OAdb < 55°F then
   SAT = 70°F
Elseif OAdb > 70°F then
   SAT = 55°F
  SAT = 125-OAdb
End if


Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en) : www.linkedin.com/in/julienmarrec<http://www.linkedin.com/in/julienmarrec>
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr<http://www.linkedin.com/in/julienmarrec/fr>

2014-09-22 20:22 GMT+02:00 Bishop, Bill <bbishop at pathfinder-ea.com<mailto:bbishop at pathfinder-ea.com>>:

I have had luck modeling DOAS by creating separate systems (as they are designed) and assigning them to the plenum spaces above the occupied spaces. The description of how to do this, and the merits and potential drawbacks, can be found in the “NEW (?) eQUEST DOAS workaround using plenum spaces” thread in his archive: http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/2013-November/thread.html


William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Julien Marrec
Sent: Monday, September 22, 2014 1:54 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] eQuest Supply temperature as function of outside air (55°F in summer, 70°F in winter)


I'm modeling a DOAS system in eQuest, and the HVAC control sequence basically calls for delivering 55°F in cooling mode and 70°F in heating mode. The heating/cooling mode is dictated by outside air temperature. This is basically in order to deliver "temperature-neutral"* outside air to the subsystems (VRV indoor units mostly - and a few corridors with simple ventilation grilles. This way the corridors some cooling, and the VRV are always only going to handle the thermal load of the space, and not the outside air load which is completely handled by the DOAS.

(*I'm more used to see OA being delivered at room temperature, say 70°F, but I didn't write the control sequence)

I've been struggling on how to properly do this in eQuest.

Right now I've got a PSZ system with a control zone being a "dummy zone" for which I've assigned a cooling schedule at constant 55°F and a heating schedule at constant 70°F. But the hourly output indicates that it's basically always providing roughly 62.5°F, so the average of my cooling and heating setpoints.

I've tried multiple ways, and read through the archives of the list, but I didn't find a working answer (maybe I'm not using the right keywords...)

Basically, is there a way to model either of these two scenarios in attachment (or online here <https://unmethours.com/upfiles/unmethours.com/14114068008016042.jpg> and here<https://unmethours.com/upfiles/unmethours.com/14114068157894564.jpg>), in eQuest for a DOAS system?

(aside from manually creating an annual schedule that would turn heating or cooling off?)

Thanks a lot,
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13<tel:%2B33%206%2095%2014%2042%2013>

LinkedIn (en) : www.linkedin.com/in/julienmarrec<http://www.linkedin.com/in/julienmarrec>
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr<http://www.linkedin.com/in/julienmarrec/fr>

PS: Original post on Unmet Hours: https://unmethours.com/question/221/equest-supply-temperature-as-function-of-outside-air/

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