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

Julien Marrec julien.marrec at gmail.com
Tue Sep 23 08:08:59 PDT 2014


Bill,

I'm inexperienced with eQuest, and all I've seen so far for DOAS + Dummy
Zone is that you should use a PSZ and assign the control zone to be the
Dummy Zone. So I guess there's no way for me to use the COOL-CONTROL
keyword, right? (I had checked if I could do that with PSZ right from the
start, but it doesn't allow it indeed...).

I've been using a workaround and I was hoping someone might tell me if they
see a problem with it.
If created an annual schedule made of 8760 hourly values that correspond to
the setpoint calculated based on the weather file outdoor temp. I
calculated each value in excel with the pseudo-code I wrote earlier (thus
being a midpoint controller), and created the schedule using RMI's EMIT
tool, and imported it in my inp file.
I then assigned this schedule to my dummy zone on both COOL-TEMP-SCH, with
a DESIGN-COOL-T = 55 and on HEAT-TEMP-SCH with a DESIGN-HEAT-T = 70.
My throttle range is 2°R, kept it here and not lower because I'm afraid off
simulatenous heating and cooling (see below)

I requested "Temp of air leaving cool coil - cold deck temp (deg F)" to my
hourly report (somehow both cooling and heating are actually reported under
this one... something I read in another thread in the archive). I'm indeed
getting the temperature I wanted.

Aside from the fact that I'm clearly not satisfied that I have to use this
manual method, having the same schedule under both heating and cooling
makes me nervous that I might have simultaneous heating and cooling. What
do you think?

Best,
Julien

PS: I've got an additional problem, I think this one is even bigger. my
"Ratio of outside air to total supply air" is always 0.54 instead of being
1. This probably has to do with the fact that I'm delivering air to both
ventilation grilles in corridor and to VRV indoor units... I don't want to
pollute this thread (full info for now if you're curious here:
https://unmethours.com/question/218/how-do-you-model-in-equest-a-doas-that-supplies-air-to-registers-corridors-as-well-as-other-hvac-systems/
)

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

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

2014-09-23 15:54 GMT+02:00 Bishop, Bill <bbishop at pathfinder-ea.com>:

>  Julien,
>
> 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.
>
> Regards,
>
> Bill
>
>
>
> *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)
>
>
>
> Bill,
>
> 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
>
> Else
>
>   SAT = 125-OAdb
>
> End if
>
>
>
> Thanks,
>
> Julien
>
>
>
>
>   --
> Julien Marrec, EBCP, BPI MFBA
> Energy&Sustainability Engineer
> T: +33 6 95 14 42 13
>
> LinkedIn (en) : www.linkedin.com/in/julienmarrec
> LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
>
>
>
> 2014-09-22 20:22 GMT+02:00 Bishop, Bill <bbishop at pathfinder-ea.com>:
>
>  Julien,
>
>
>
> 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
>
>
>
> Regards,
>
> Bill
>
>
>
> *William Bishop, PE, BEMP, BEAP, CEM, LEED AP **|** Pathfinder Engineers
> & Architects LLP*
>
> *Senior Energy Engineer*
>
>
>
>
>
> 134 South Fitzhugh Street                 Rochester, NY 14608
>
> *T: (585) 698-1956*                        F: (585) 325-6005
>
> bbishop at pathfinder-ea.com <wbishop at pathfinder-ea.com>
> www.pathfinder-ea.com
>
> [image: http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon
> Fee and Dividend - simple, effective, and market-based.
>
>
>
> *From:* Equest-users [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
> *Subject:* [Equest-users] eQuest Supply temperature as function of
> outside air (55°F in summer, 70°F in winter)
>
>
>
> Hi,
>
> 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
>
> --
> Julien Marrec, EBCP, BPI MFBA
> Energy&Sustainability Engineer
> T: +33 6 95 14 42 13
>
> LinkedIn (en) : www.linkedin.com/in/julienmarrec
> LinkedIn (fr) : 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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