[EnergyPlus_Support] Re: Using AFN for windows, but with default infiltration

["allinson_louis" <allinson_louis@xxxxxxxxxxx>]

Thanks Joe, you understood my problem correctly. I cannot use zone infiltration as i can then no longer calculate air flow through windows. It seems I will have to play around with my crack objects to get an infiltration value that I want

cheers
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Joe Huang <YJHuang@...> wrote:
>
> I'm afraid you're missing the point.  The original question was how to model infiltration 
> when the AFN is being used.
> My point was that you cannot mix the infiltration object in conjunction with the AFN.  If 
> you want to model infiltration with the AFN, you have to define the leakage 
> characteristics of the space for the AFN  (this should probably be done anyway for proper 
> modeling - in fact, all these AFN programs such as COMIS and AirNet were originally 
> designed not for modeling natural ventilation, but rather infiltration).
> 
> 
> Sure, you can use a blower door test to get the leakage fraction, but that has to be used 
> as an input to the AFN, not to the infiltration object.   I've always been adverse to 
> modeling infiltration as a constant air change rate, because that's nonphysical and not 
> what really happens.  IMHO, it's always much better to define the physical characteristics 
> of the space (leakage-fraction, area of cracks, etc.) and then use a physical model like 
> the Sherman-Grimsrud or the AFN to then compute the hour-to-hour infiltration.
> 
> 
> Joe
> 
> 
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 108D
> Moraga CA 94556
> yjhuang@...
> http://weather.whiteboxtechnologies.com for simulation-ready weather data
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
> 
> 
> 
> 
> On 3/10/2013 9:25 AM, Oscar Hernandez wrote:
> >
> > There are many methods to calculate the real infiltration value...like the blower test.
> >
> > On Oct 3, 2013 6:06 PM, <josep.sole@... <mailto:josep.sole@...>> wrote:
> >
> >     In AFN models you need to assume a lot of other hypothesis it is no easier than
> >     assume the zone infiltration rate.
> >
> >     *Josep Sol��
> >     URSA Insulation S.A**- *
> >
> >     *Sustainibility & Technical Manager *
> >
> >     *M��vil +34 606 42 32 14 <tel:%2B34%20606%2042%2032%2014>*
> >
> >     *www.ursa.es <http://www.ursa.es/>***
> >
> >     *www.ursainsulation.com <http://www.ursainsulation.com>***
> >
> >     *www.uralita.com <http://www.uralita.com/>*
> >
> >     ***cid:image002.gif@...
> >     **P **URALITA / URSA se compromete con el ahorro de energ��a. Antes de imprimir este
> >     mensaje aseg��rese de que es necesario**.***
> >
> >     *De:*EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>
> >     [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> >     <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>] *En nombre de *Oscar Hernandez
> >     *Enviado el:* jueves, 03 de octubre de 2013 17:57
> >     *Para:* EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>
> >     *Asunto:* Re: [EnergyPlus_Support] Using AFN for windows, but with default infiltration
> >
> >     If you want to model an infiltration value use the zone infiltration. The AFN its to
> >     predict the infiltrattion value when you don"t know it.
> >
> >     On 3 October 2013 17:42, Joe Huang <YJHuang@...
> >     <mailto:YJHuang@...>> wrote:
> >
> >     I don't think the infiltration objects can be used in conjunction with the AFN. That
> >     would violate the mass balance of the AFN, wouldn't it?
> >
> >     Sent from my IPad
> >
> >     Joe Huang
> >
> >
> >     On Oct 3, 2013, at 8:35 AM, Oscar Hernandez <eng.ohw@...
> >     <mailto:eng.ohw@...>> wrote:
> >
> >         Hi,
> >
> >         Use the zone infiltration.
> >
> >         Oscar
> >
> >         On Oct 3, 2013 2:48 PM, "allinson_louis" <allinson_louis@...
> >         <mailto:allinson_louis@...>> wrote:
> >
> >         Hi All
> >
> >         I am using AFN to model air flow through window openings that I am controlling
> >         using EMS
> >
> >         However, when the windows are closed the only infiltration is through cracks and
> >         the infiltration is much less than 0.1ach. I want to model a 'default' 0.1ach
> >         when the windows are closed, as this is a typical value used in simulations.
> >
> >         Is this possible?
> >
> >
>




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