[EnergyPlus_Support] Re: Infiltration

["FrancescoP" <direzionecontraria@xxxxxxxx>]

Very interesting, Jean. I have not understood some aspects.
You divided by the "Air Mass Flow Exponent When Window or Door Is Closed". Why? I mean, I don't know what equation you referred to.
In order to get "kg/s @ 1Pa per m crack" why didn't you divide by the total length of the cracks?
What object of EnergyPlus did you use to implement the results?
Best Regards
Francesco


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais"  wrote:
>
> I'm interested in this subject. I once setup manually the air tightness in the following way: 
> 
> e.g.
> Infiltration of closed exterior windows/doors is set for a relatively tightly sealed building at 0.3 ACH at 50Pa Blower Door. This is achieved by taking the building volume 2057 m³ at 0.3 ACH = 617.1 m³/h = 0.171466 m³/s divided equally over the number of exterior window/door cracks,
> 
> i.e. Baseline Building has 119 exterior window/door x4 cracks each (top, bottom, side, side) ï?  crack Air Mass Flow Coefficient When Window or Door Is Closed (kg/s @ 1Pa per m crack) = ((0.171466)/(119x4))/((50)(0.5) ) = 0.00005092852413
> 
> where Air Mass Flow Exponent When Window or Door Is Closed (dimensionless) = 0.5
> 
> Interior doors are modeled as always closed with (both baseline and design models) the crack Air Mass Flow Coefficient When Window or Door Is Closed (kg/s @ 1Pa per m crack) = (0.024[1])/ (4 cracks x (25)(0.65) ) = 0.000725
> 
> [1] Poulsen, P.E. â??Smoke Control Doors Test Reportâ?? Danish Nat Inst for Testing of Materials, Copenhagen (1979)
> 
> All edges
> Avg Gap Thickness mm = 0.6 mm
> Gap Depth = 60 mm
> Gap Length = 6.0 m
> Flow Rate = 0.024 m³/s
> 
> Cracks are not modeled for non-openable interior windows.
> Holes are assumed to have Air Mass Flow Coefficient (kg/s @ 1Pa per m crack) = 0.1 and Air Mass Flow Exponent (dimensionless) = 1.0 for free flow without resistance.
> 
> ....................this was a simple 29 room one story building.
> 
> I have not checked the latest from designbuilder for the n50 proceedure and natural ventilation, but am looking forward to in the future.
> 
> Jean 
> 
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jeremiah Crossett  wrote:
> >
> > Thanks Ned-
> > You might check how this feature works when natural ventilation is set to
> > calculated and scheduled-- It would make since that when calculated is
> > checked the AFN infiltration  objects are used on all external surfaces but
> > when scheduled is checked than infiltration is modeled
> > ZoneInfiltrationDesignFlowRate..
> > *
> > *
> > *
> > *
> > *Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions*
> > *
> > 120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
> > www.phasechange.com
> > *
> > 
> > *
> > *
> > *
> > *
> > 
> > 
> > 
> > On Fri, Feb 1, 2013 at 10:40 AM, Edward G. Lyon  wrote:
> > 
> > > **
> > >
> > >
> > >  Thanks, we have Design Builder in the company, but I don�t use it
> > > myself.  When I have some time I�ll check out what they do exactly.****
> > >
> > > ** **
> > >
> > > *Ned Lyon, P.E. (MA, WV)**
> > > *Staff Consultant ****
> > >
> > > *SIMPSON GUMPERTZ & HEGER** *
> > > 781.907.9000 main
> > > 781.907.9350 direct
> > > 781.907.9009 fax
> > > www.sgh.com****
> > >
> > >   ****
> > >
> > > *From:* EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:
> > > EnergyPlus_Support@xxxxxxxxxxxxxxx] *On Behalf Of *Jeremiah Crossett
> > > *Sent:* Friday, February 01, 2013 1:34 PM
> > > *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > *Subject:* Re: [EnergyPlus_Support] Infiltration****
> > >
> > > ** **
> > >
> > >   ****
> > >
> > > I agree with Ned, but also think it is worth mentioning that Design
> > > Builder has a simple input from blower door to Energy Plus that might be
> > > worth looking into, and I have attached a screen shot of the input. I am
> > > not 100% sure how DB applies this to its E+ file generation but assume it
> > > uses the ZoneInfiltrationDesignFlowRate Object pasted from another file
> > > below. I think there is a better way to do it with airflow network as well.
> > > ****
> > >
> > > ** **
> > >
> > > Name Infiltration****
> > >
> > > Zone or ZoneList Name     Zone****
> > >
> > > Schedule Name       On****
> > >
> > > Design Flow Rate Calculation Method     Flow/zone****
> > >
> > > Design Flow Rate    0.018****
> > >
> > > Flow per Zone Floor Area  ****
> > >
> > > Flow per Exterior Surface Area     ****
> > >
> > > Air Changes per Hour        ****
> > >
> > > Constant Term Coefficient  1****
> > >
> > > Temperature Term Coefficient     0****
> > >
> > > Velocity Term Coefficient   0****
> > >
> > > Velocity Squared Term Coefficient          0****
> > >
> > > ** **
> > >
> > > ** **
> > >
> > > ** **
> > >
> > > *Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions*
> > > ****
> > >
> > > *120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951***
> > >
> > > *www.phasechange.com ***
> > >
> > >   ****
> > >
> > > ** **
> > >
> > > ** **
> > >
> > > ** **
> > >
> > > ** **
> > >
> > > On Fri, Feb 1, 2013 at 10:15 AM, Edward G. Lyon  wrote:***
> > > *
> > >
> > >   ****
> > >
> > > In my opinion, the answer to your question is very complex.  I am not sure
> > > what you mean precisely by 50Pa test.  Usually this means ACH50 (air
> > > changes per hour at 50 Pa), but you could have a complete test that reports
> > > Coef and Expon for the flow equation Flow = Coef*Pressure^Expon.****
> > >
> > >  ****
> > >
> > > In either case there is no short cut way I see to put this data directly
> > > into EnergyPlus.****
> > >
> > >  ****
> > >
> > > I also think different procedures may apply to different types of
> > > buildings.  If you have a small house, and ACH50 result divided by 20
> > > (sometimes other factors) is a fair approximation of the infiltration air
> > > exchange rate for a small building.  You could define Infiltration as an
> > > ACH and juggle the coefficients to give you a better guess for seasonal
> > > temperature and wind conditions.  Or you could study the research on ACH50
> > > correlations to infiltration and schedule something appropriate for your
> > > location.  If you have a commercial building, your test data should be unit
> > > area based and you would use Infiltration with a surface area calculation.
> > > ****
> > >
> > >  ****
> > >
> > > Infiltration in EnergyPlus has a sophisticated set of input parameters
> > > intended to vary infiltration by site conditions, and I have done a lot of
> > > whole building testing.  Perhaps others can provide a good reference for
> > > integrating measured data into the energy model, but I have not seen it.  I
> > > think there may a way to approximate the pressure from the temperature and
> > > wind in order to recalculate coefficients for Infiltration in EnergyPlus.
> > > Perhaps I need to study this in more depth myself.****
> > >
> > >  ****
> > >
> > > From my testing work I also know that not all parts of the building leak
> > > the same.  There may be different results for different zones (roof to wall
> > > edges leak more than field of wall).  This is likely to influence some
> > > zones more than others.  Also a very leaky roof above very tight walls will
> > > give you a very leaky test result, but the actual infiltration affecting
> > > energy could be much less.      ****
> > >
> > >  ****
> > >
> > > For a recent model that looked at temperature conditions and not energy, I
> > > was able to use an air flow network.  The equations there are more easily
> > > adaptable to the results of a building blower door test and the analysis
> > > automatically calculates pressures based on wind and temperature.  This can
> > > get complicated for larger buildings, and may not work with other fans in a
> > > mechanical system.****
> > >
> > >  ****
> > >
> > > Now it is not my intention to offend all the serious and dedicated energy
> > > modelers out there who put infiltration into their models.  I just don�t
> > > see how it is currently much more than a guess or accepted practice, and I
> > > would be interested in any available information on correlating test data
> > > to models.  I get asked that question a lot, and each energy model
> > > calculates infiltration in a slightly different way. ****
> > >
> > >  ****
> > >
> > > *Ned Lyon, P.E. (MA, WV)
> > > *Staff Consultant ****
> > >
> > > *SIMPSON GUMPERTZ & HEGER** *
> > > 781.907.9000 main
> > > 781.907.9350 direct
> > > 781.907.9009 fax
> > > www.sgh.com****
> > >
> > >   ****
> > >
> > > *From:* EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:
> > > EnergyPlus_Support@xxxxxxxxxxxxxxx] *On Behalf Of *FrancescoP
> > > *Sent:* Friday, February 01, 2013 12:09 PM
> > > *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > *Subject:* [EnergyPlus_Support] Infiltration****
> > >
> > >  ****
> > >
> > >   ****
> > >
> > > I wonder what the best ways to model infiltration in these two cases are:
> > > 1. you know the result of the blower door test (50Pa)
> > > 2. no blower door test was made but you know how the building was built
> > > Any idea?
> > > With Regards****
> > >
> > > ** **
> > >
> > > ****
> > >
> > >  
> > >
> >
>



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