[Equest-users] Unmet hours in residential building

[Joe Huang]

Mike,

Allow me to jump in here a bit.  Have you looked at the SV-A report to see what DOE-2.2 
has sized for the HVAC system, particularly the supply-cfm and heating/cooling capacities 
for the bathroom ?

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 10/28/2015 1:17 PM, Michael Campbell wrote:
> I've tried different values for the degree day multipliers, into the hundreds.  I'm 
> trying out different scenarios now to see what works, but I'm still getting unmet 
> heating hours in the bathroom.
>
> On Wed, Oct 28, 2015 at 3:57 PM, Julien Marrec <julien.marrec at gmail.com 
> <mailto:julien.marrec at gmail.com>> wrote:
>
>     Mike,
>
>     You have set a zonal exhaust with make up air defined as infiltration? And your
>     space linked to the thermal zone has an infiltration defined as ACH with a higher
>     value for design days? How much higher?
>     Your HVAC is autosized for the zone?
>     Do you still have unmet hours for the bathroom?
>
>     If this is not doing anything, your HVAC system might be already autosized to a
>     greater value due to another parameter such as sizing factor so that the added
>     infiltration does nothing.
>     Or maybe your zonal fan doesn't actually run? Try and request some hourly variables
>     to understand what is going on.
>
>     Julien
>     Envoyé de mon iPhone
>
>     Le 28 oct. 2015 à 20:27, Michael Campbell <mcamp1206 at gmail.com
>     <mailto:mcamp1206 at gmail.com>> a écrit :
>
>>     Julien,
>>
>>     Regarding the infiltration method... I am currently trying to do this with a small
>>     bathroom with 50cfm exhaust.  This is a core zone.  Adjusting the design day values
>>     as described in the write-up does not appear to be doing anything.  Any thoughts?
>>
>>     Thanks,
>>     Mike
>>
>>     On Thu, Oct 15, 2015 at 11:45 AM, Julien Marrec <julien.marrec at gmail.com
>>     <mailto:julien.marrec at gmail.com>> wrote:
>>
>>         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 <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>
>>
>>         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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>>
>
>
>
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