[Equest-users] Infiltration issues whith more than one shell

Joe Huang yjhuang at whiteboxtechnologies.com
Thu Mar 1 19:32:18 PST 2018


I don't think Bruce's comment is germaine to the problem posed by Menush, since Menush is 
asking about infiltration and not heat transfer through interior walls.  As far as I know 
from DOE-2 (always have to add that caveat because I don't work much in eQUEST), 
infiltration rates are normalized per floor area, rather than external wall area, mainly 
because that's how the infiltration models have been developed, i.e., effective leakage 
areas have always been defined as per floor area.  If you don't think that's right, you 
can always adjust the input values by the ratio of the external wall area to the floor 
area, as you've described, but then you're on your own in coming up with the correlation,

Joe

Joe Huang
White Box Technologies, Inc.
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Moraga CA 94556
yjhuang at whiteboxtechnologies.com
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On 3/1/2018 6:44 PM, Bruce Easterbrook via Equest-users wrote:
> Hi Menush,
> I don't think you have the same thing.  eQuest will treat 2 shells butted to each other 
> differently than a single interior wall separating 2 zones in a shell.  It treats the 2 
> butted walls as exterior walls with a tiny space between.  They are the same wall in 
> your thinking but they are not.  You can delete one of them and make the remaining wall 
> an interior wall and assign the proper butting spaces on each side of the wall as 
> sharing the wall and transferring heating and cooling through the wall.  Or you can add 
> an interior wall to the original space and separate it into 2 zones.  As you have 
> noticed there is a difference in the way eQuest treats your 2 solutions.  It is 
> particular.  Now you need to pick the configuration that matches what you are trying to 
> model in such a way that eQuest does/treats the wall in the way you want it to work.
> Bruce Easterbrook P.Eng.
> Abode Engineering
>
> On 3/1/2018 5:23 PM, Menush Akbari via Equest-users wrote:
>>
>> Hi all,
>>
>> I’m having an issue with infiltration and wondering if anyone else has noticed this. 
>> When I’m in wizard mode, I build a very simple rectangular shell and I change the 
>> infiltration rate for perimeter zones to 0.05cfm/ft2. I leave the core zone 
>> infiltration rate to the eQuest default value (0.001cfm/ft2). From my understanding, 
>> the perimeter zone entered value in wizard mode is based on exterior gross wall area. 
>> When I move on to detail mode, eQuest changes the value to an infiltration value per 
>> floor area instead of exterior wall area. The values so far make sense and I can do the 
>> math and get the same numbers eQuest calculates in detail mode. No problems here.
>>
>> The problem however happens when I create different shells. For example, let’s say I 
>> have the same rectangular building as mentioned above, but I split this up into two 
>> different shells next to each other (two square shells), therefore one of the walls of 
>> each square shell is an interior wall, which means I should not see an infiltration of 
>> 0.05 cfm/ft2 of the gross wall area. However when I finish building these two shells in 
>> detail mode (which would be identical to one rectangular shell), the infiltration value 
>> is not accurate anymore. Instead of the same numbers as my first model (one rectangular 
>> shell), the second model calculates an exterior wall infiltration value for the 
>> interior walls that are budded up against each other.
>>
>> Has anyone come across this? Is this a quirk with eQuest and just needs to be changed 
>> manually in detail mode, or am I doing something wrong here?
>>
>> Thanks for the help.
>>
>> Cheers,
>>
>> *Menush Akbari*
>>
>> BEng, PEng, BEMP, CMVP
>>
>> Senior Energy Engineer
>>
>> Mission Green Buildings
>>
>> /(Mission Green Buildings is the trading name of Mission Green Limited)/
>>
>> t. 250 777 3380
>>
>> makbari at missiongreenbuildings.com <mailto:makbari at missiongreenbuildings.com>
>>
>> _http://missiongreenbuildings.com <http://missiongreenbuildings.com/>_
>>
>> MGB 5 Years 2
>>
>>
>>
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