[Equest-users] [External] Re: Unmet hours in residential building

[Porter, Frederick NOR]

Since I’m on a roll, I’ll add to Michael’s observations;
The HVAC is all auto-sized. The design cool t in the attached model is set to 75F in all zones, including unconditioned attics and heated only spaces. The design heat t is 75F in the “roof zone.” Any cooled space adjacent to these could be undersized for cooling; since the cooling design interior wall/ceiling heat flows are based on the difference in the cooling design ts. You can arbitrarily increase those temps, or turn on zone reports for those zones (defaults to NO for unconditioned and plenum zones) and look at their actual peak temps and use the numbers from the zone reports. Similar for heating, and the attic,  except the model design heat t = 75F and zn max heat setpt = 72F which results in a little hidden safety factor.

VERY common issue. It’s so nice to look at DOE-2 files that I can understand; I’m now wading into E+, OS, Simergy…

Fred

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Julien Marrec
Sent: Thursday, October 15, 2015 9:46 AM
To: Michael Campbell
Cc: equest-users at lists.onebuilding.org
Subject: [External] Re: [Equest-users] Unmet hours in residential building

Michael,
First, you're under 300 hours so indeed it's a minor problem.
I've only looked at your model very briefly but:

  *   HW loop operation is set to "SNAP" at OA of 60°F. This is causing some minor underheating in shoulder season.

  *   You have local exhaust fan with makeup = infiltration. Basically equest ignores this added infiltration during the sizing, so you have to trick it to take it into account by having a different schedule for sizing (heating AND cooling design days). I've put together my findings on the subject on Unmet Hours here<https://unmethours.com/question/3102/how-do-you-model-exhaust-fans-in-equest/> in some kind of tutorial that I hope is helpful.



Do the above and your unmet hours disappear.



Additionally:

  *   Throttle range of 0.3°R seems pretty aggressive to me.
  *   when you use baseboards and want to oversize, use the system's sizing ratio

Hope this helps,
Julien


--
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>

2015-10-15 16:30 GMT+02:00 Michael Campbell <mcamp1206 at gmail.com<mailto:mcamp1206 at gmail.com>>:
I mistakenly attached the PRD file instead of PD2.  Correct files are attached.

On Thu, Oct 15, 2015 at 10:16 AM, Michael Campbell <mcamp1206 at gmail.com<mailto:mcamp1206 at gmail.com>> wrote:
Hello,
I'm having what appears to be a minor issue with unmet hours in a model that I've inherited.  My INP and PD2 files are attached.  I've tried adjusting the cool sizing ratio and and adjusted infiltration rates and equipment loads with no real effects.  Anybody have any ideas?
Thanks,
Mike Campbell


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