[Equest-users] How to model a DOAS serving corridors with a Chilled Water Coil

[Julien Marrec]

I'm in no way an expert here, otherwise I wouldn't be asking for help.

But I don't think it does anything you can't do otherwise. Last time I
switched between a PVAVS and PSZ and was able to recreate the same results
(PSZ with dummy zone, and PVAVS with some more complex steps to set
discharge temp correctly. The PVAVS solution is more flexible though).

It's just easy to use a dummy zone, it's what comes up mostly when
searching for "equest" and "doas" keywords, and there's even a tutorial
video <http://energy-models.com/make-air-equest>.


Do you think differently Bill?


--
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>

2014-12-08 17:16 GMT+01:00 Bishop, Bill <bbishop at pathfinder-ea.com>:

>  How does using a dummy zone give you extra capability and/or accuracy
> modeling discharge air temperature control, and how is the simulated energy
> consumption more accurate?
>
> Thanks,
>
> Bill
>
>
>
> *From:* Julien Marrec [mailto:julien.marrec at gmail.com]
> *Sent:* Monday, December 08, 2014 11:06 AM
> *To:* Nathan Miller
> *Cc:* Bishop, Bill; Nicholas Caton; equest-users at lists.onebuilding.org
>
> *Subject:* Re: [Equest-users] How to model a DOAS serving corridors with
> a Chilled Water Coil
>
>
>
> Bill,
>
> There is nothing fancy in my AHU. Just a fan and a coil. Always 100%
> outside air, the same amount of CFM (no economizer), and no return airflow.
> Discharge temperature is fixed (Tstat in discharge air stream is
> controlling a three way valve on the coil). The system doesn't know and
> doesn't care about what's happening in the space it serves.
>
> As Nathan was saying, I was thinking about using a Dummy zone to control
> the discharge temp indeed, like I usually do with PSZ systems: you have to
> give it a control zone, and the dummy serves this purpose.
>
> But as I'm trying to switch from VAVS to 2pipe FC right now, I realize
> this isn't the way it works with FC. I think I'll keep my VAVS solution for
> now. It seems too cumbersome to change it now and I'd have to attribute an
> outdoor air CFM numbers to all my zones served by the system.
>
> Thanks all,
> 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
>
>
>
> 2014-12-08 16:38 GMT+01:00 Nathan Miller <nathanm at rushingco.com>:
>
>  I personally use dummy zones on corridor units when I’m trying to model
> a system that uses discharge air temperature control rather than one that
> responds to a thermostat in the corridor. On single zone systems with
> control given to a dummy zone (with no internal or envelope loads), you can
> force the system to discharge air with-in a specific temperature band
> year-round. Of course you then have to give the actual corridor spaces a
> t-stat schedule that is rather accommodating or else you might end up with
> lots of unmet load hours.
>
> *Nathan Miller, PE, LEED AP BD+C** – **Mechanical Engineer/Senior Energy
> Analyst*
>
> *RUSHING* | *D* 206-788-4577 | *O* 206-285-7100
>
> *www.rushingco.com* <http://www.rushingco.com/>
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Bishop, Bill
> *Sent:* Monday, December 08, 2014 10:28 AM
> *To:* Julien Marrec; Nicholas Caton
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] How to model a DOAS serving corridors with
> a Chilled Water Coil
>
>
>
> Julien,
>
> Why would you model this with a dummy zone? If your DOAS is only supplying
> the corridor, just model the corridors as separate zones and assign the
> DOAS system to them.
>
> You didn’t say whether or not the DOAS has heat recovery. That will
> further dictate which system type you select. FC does not allow heat
> recovery, but VAVS and Single Zone Reheat do.
>
> Regards,
>
> Bill
>
>
>
> *William Bishop, PE, BEMP, BEAP, CEM, LEED AP **|** Pathfinder Engineers
> & Architects LLP*
>
> *Senior Energy Engineer*
>
> [image: cid:image001.jpg at 01D012D2.77E28370]  [image:
> cid:image002.jpg at 01D012D2.77E28370]
>
>
>
> 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
> <equest-users-bounces at lists.onebuilding.org>] *On Behalf Of *Julien Marrec
> *Sent:* Monday, December 08, 2014 9:58 AM
> *To:* Nicholas Caton
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] How to model a DOAS serving corridors with
> a Chilled Water Coil
>
>
>
> Thanks for your message Nick.
>
> I now have a 2-pipe loop with the SNAP-T, thanks for pointing it out.
>
> David Elridge also wrote that I could just subsitute PSZ for a 2pipe FC.
>
>
>
> I've got something working right now that is based on VAVS.
>
> I have read the help file before posting.I understand there are many ways
> to skin a cat in eQuest, but I'm still confused what fundamental difference
> it would make between using a VAVS or using a 2pipe FC with a dummy zone.
> Aside from the fact that the dummy zone setup is easier to implement I
> guess... Is there a wrong way to do this? Or just a better way?
>
> 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
>
>
>
> 2014-12-08 13:20 GMT+01:00 Nicholas Caton <ncaton at catonenergy.com>:
>
>  Hi Julien,
>
>
>
> I think there are multiple options that could fit the criteria you’ve
> provided, more than one could work depending on circumstances of your
> project…
>
>
>
> *General* advice for “what system should I use” queries follows.
>
> 1.       Ask a few questions of the system equipment/design:
>
> -          How the actual system is controlled – is it constant volume
> with heating/cooling triggered via one space/duct thermostat only, or
> something more complex?
>
> -          Do you have just one central fan or additional fans in each
> zone for independent circulation?
>
> -          One set of central heating/cooling coils or are there separate
> reheat / cooling coils occurring at individual zones?
>
> 2.       QC your work:
>
> -          Answer for yourself how the system’s fans/cooling/heating
> should operate, and when/to what degree ventilation OA is delivered
>
> -          After initially setting up your systems/zones (or perhaps the
> first set of many), perform some test runs to QC your efforts
>
> -          Verify each intended behavior/output via hourly reporting
>
>
>
> Considering you can generally force 100% OA and constant volume  with
> system and/or zonal minimum OA/flow ratio inputs, as appropriate, peruse
> the help file diagrams for systems of interest that include features of
> interest.  You probably want to consider/review the articles for FC, VAVS,
> and PIU.
>
>
>
> From your coil description, you may further consider an airside system
> type to leverage a 2-pipe loop set to an outdoor snap temperature (or
> perhaps a seasonal schedule) – see the operation tab under the loop in
> detailed edits.
>
>
>
> Hope that helps get you started!
>
>
>
> ~Nick
>
>
>
> *NICK CATON, P.E.*
> *Owner*
>
>
>
> *Caton Energy Consulting*
>   1150 N. 192nd St., #4-202
>
>   Shoreline, WA 98133
>   office:  785.410.3317
>
> www.catonenergy.com
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Julien Marrec
> *Sent:* Monday, December 08, 2014 3:29 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] How to model a DOAS serving corridors with a
> Chilled Water Coil
>
>
>
> Hi,
>
> I've got a building with a DOAS (AHU with 100% outside air) serving
> corridors (no reheat, no fan in there, just ventilation grilles). The DOAS
> has one coil, served by hot water in winter and cold water in summer.
>
> There is no economizer, and the supply temperature is simply set by a
> thermostat set as 70°F year round.
>
> I have modeled DOAS before but I was using a PSZ or a PVVT. Those have DX
> cooling coils, so it's not an option.
>
> Seems like I could use MSZ or VAV for example, but I'm not sure which
> would be more appropriate.
>
>
> What type of system do you recommend using in my case?
>
> How would you control it in order to get the proper supply temperature
> (70°F) and avoid simultaneous heating and cooling (Is using an availability
> schedule the only option?)?
>
>
>
>
>
> Also, if you have an .inp snippet I could use to set it up correctly, I'll
> greatly appreciate it!
>
>
>
>
>
> 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
>
>
>
>
>
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