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

[Javed Iqbal]

Hello,

Its worth trying detailed DOAS modeling methodology shared by Mr. James
Hess some time back. This requires bit of extra postprocessing but it gives
you most realistic work around within the limits of eQuest.  You can search
with this subject line ( Baseline PTAC Fan Energy for a Proposed Merv13 +
Return Duct System - Goodness Me I had No Idea).
On 23 Sep 2014 21:21, "Bishop, Bill" <bbishop at pathfinder-ea.com> wrote:

>  Julien,
>
> I have never spent much time trying to use dummy zones as an eQUEST
> workaround. Maybe it can be made to work but for me it looks like it
> creates more problems than it solves. I'll leave it at that.
>
> Prior to the "plenums" method I described, I always modeled DOAS as best I
> could using the heat recovery features available to some of the system
> types. It can be a challenge to capture all heating, cooling, fan energy,
> heat recovery, and heat recovery penalties (especially added fan energy and
> sometimes pumping energy, but also added heating and/or cooling energy
> depending on the heat recovery/system controls).
>
> For OA, the important thing is to make sure your total annual OA CFM is
> what you want it to be, and that it is the same in the baseline (if you
> have a baseline). One of the potential issues with the DOAS workarounds is
> that you may not be conditioning the OA using the actual designed
> combination of heating and cooling plants and their corresponding
> efficiencies, though that is not usually a problem for the plenums
> workaround. A good way to force the OA to be what you want is to enter it
> at the ZONE level, and/or use a MIN-AIR-SCH. Also, using OA-FROM-SYSTEM can
> be tricky and there have been many comments on equest-users describing
> pitfalls and warnings. I avoid using it, preferring to lump OA into
> different zones and systems according to what the eQUEST system types can
> handle, but always making sure total building OA is accurate. I also like
> to create airwalls between zones whenever I model a zone's OA by shifting
> it to an adjacent zone (such as when air is transferred between zones), to
> minimize unmet load hours and make the return air temperature more
> realistic.
>
>
>
> Regards,
>
> Bill
>
>
>
> *From:* Julien Marrec [mailto:julien.marrec at gmail.com]
> *Sent:* Tuesday, September 23, 2014 11:09 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'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
>
>
>
> 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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