[EnergyPlus_Support] Re: AFN - how to set up air tightness of envelope

["Jean marais" <jeannieboef@xxxxxxxxx>]

Thanks Jason,

Actually, I had read that the first time about 2 months ago. It's the best I've found. Works very well with the infiltration objects, this approach. I guess calculating infiltration is a 2 edged sword. On the one hand we want to simulate it accurately, and on the other hand we're too lazy to calculate all the input parameters properly.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jason Kirkpatrick <jason.alan.kirkpatrick@...> wrote:
>
> All,
> 
> There is also some additional guidance for calculating the wind-driven
> infiltration coefficients found here:
> 
> http://www.pnl.gov/main/publications/external/technical_reports/PNNL-18898.pdf
> 
> -Jason
> 
> 
> On Mon, Oct 31, 2011 at 9:15 AM, Jim Dirkes <jim@...
> > wrote:
> 
> > **
> >
> >
> > Dear Jean,****
> >
> > A mon avis�..Infiltration is impossible to define in a way that matches
> > reality unless you have a LOT of measured data along with the corresponding
> > wind speed and direction data.****
> >
> > I generally decide that infiltration is acceptably modeled using:****
> >
> >  ****
> >
> > *ZoneInfiltration:DesignFlowRate*
> >
> > Name****
> >
> > Infiltrn_ZoneName****
> >
> > Zone Name****
> >
> > 02-12-North****
> >
> > Schedule Name****
> >
> > SchCpct_AlwaysOn****
> >
> > Design Flow Rate Calculation Method****
> >
> > AirChanges/Hour****
> >
> > Design Flow Rate****
> >
> > MT****
> >
> > Flow per Zone Floor Area****
> >
> > MT****
> >
> > Flow per Exterior Surface Area****
> >
> > MT****
> >
> > Air Changes per Hour****
> >
> > 0.3****
> >
> > Constant Term Coefficient****
> >
> > 0.606****
> >
> > Temperature Term Coefficient****
> >
> > 0.03636****
> >
> > Velocity Term Coefficient****
> >
> > 0.1177****
> >
> > Velocity Squared Term Coefficient****
> >
> > 0****
> >
> > ** **
> >
> > The �Air Changes per Hour� value is a *guess* based on the construction
> > quality, but I will normally use <= .3 for new construction. For interior
> > zones, I�ll sometimes use 0 or delete the infiltration object.****
> >
> > The coefficients came from the IO Reference (I think) and are leftovers
> > from the DOE or BLAST programs which modify the infiltration amount based
> > on wind speed.  Since infiltration is affected by wind speed, it seems
> > appropriate to vary infiltration according to wind speed.****
> >
> > ** **
> >
> > *The Building Performance Team
> > **James V. Dirkes II, P.E., BEMP , LEED AP
> > *1631 Acacia Drive NW
> > Grand Rapids, MI 49504
> > 616 450 8653****
> >
> > ** **
> >
> > *From:* EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:
> > EnergyPlus_Support@xxxxxxxxxxxxxxx] *On Behalf Of *Lixing Gu
> > *Sent:* Monday, October 31, 2011 11:07 AM
> > *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> > *Subject:* RE: [EnergyPlus_Support] Re: AFN - how to set up air tightness
> > of envelope****
> >
> > ** **
> >
> >   ****
> >
> > Jean:
> >
> > I am curious to know what is your definition of "a real life realistic
> > infiltration character of the building". Do you know a real building has a
> > constant infiltration rate of 0.3 ACH?
> >
> > Lixing
> >
> > -----Original Message-----
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> > Sent: Saturday, October 29, 2011 4:34 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Re: AFN - how to set up air tightness of
> > envelope
> >
> > That answer is good, but now I should build in a fan to pressurize my
> > building to 50 Pa and monitor what volume flow is reported, gradually
> > increasing the parameter you suggested until the volume flow equals 0.3 ACH
> > for the building which reflects a realistic building envelope sealing?
> >
> > I guess what I'm saying is that even with knowing which parameters will
> > increase or decrease the infiltration rates, I still have no idea how to
> > set
> > up the system to reflect a real life realistic infiltration character of
> > the
> > building.
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> > >
> > > If the AirflowNetwork:MultiZone:Component:DetailedOpening objects are
> > used,
> > > you may adjust the values of the Air Mass Flow Coefficient When Opening
> > is
> > > Closed field.
> > >
> > > Hope this helps.
> > >
> > > Lixing
> > >
> > > -----Original Message-----
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> > > Sent: Thursday, October 27, 2011 2:09 PM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > Subject: [EnergyPlus_Support] AFN - how to set up air tightness of
> > envelope
> > >
> > > Design Builder has generated me a wonderfully large AFN. As default, all
> > my
> > > windows are closed all the time.
> > >
> > > 1) How do I realistically define an "air tightness" for windows that
> > don't
> > > open?
> > > 2) For windows that do open, but are closed.
> > >
> > > using AFN object fields such as minimum crack opening factor, etc.
> > >
> > >
> > ----------------------------------------------------------
> > > ---
> > >
> > > I'm thinking of increasing the minimum crack width untill my zones are
> > > reporting infiltration rates of about 0.35 ACH (well sealed building).
> > > Then I can add extra infiltration by playing with the openable windows
> > and
> > > their schedules.
> > >
> > >
> > >
> > > ------------------------------------
> > >
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> > >
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> > >
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> >
> > ------------------------------------
> >
> > Primary EnergyPlus support is found at:
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> >
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> >
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> >
> > ****
> >
> >  
> >
>




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