Re: [EnergyPlus_Support] infiltration

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The question of typical values for these coefficients is subject to 
debate.  Ideally, one should do a detailed analysis of the 
infiltration situation and then determine a custom set of 
coefficients using methods such as those laid out in Chapter 26 of 
the ASHRAE Handbook of Fundamentals.  The EnergyPlus defaults are 
1,0,0,0 which gives a constant volume flow of infiltration under all 
conditions.  

BLAST used the following values as defaults:  0.606, 0.0202, 
0.000598, 0.  These coefficients produce a value of 1.0 at 0C deltaT 
and 3.35 m/s (7.5 mph) windspeed, which corresponds to a typical 
summer condition.  At a winter condition of 40C deltaT and 6 m/s 
(13.4 mph) windspeed, these coefficients would increase the 
infiltration rate by a factor of 2.75.  

In DOE-2, the air change method defaults are (adjusted to SI units) 
0, 0, 0.224 (windspeed), 0.  With these coefficients, the summer 
conditions above would give a factor of 0.75, and the winter 
conditions would give 1.34.  A windspeed of 4.47 m/s (10 mph) gives a 
factor of 1.0.  

The source of the BLAST defaults is noted in the BLAST documentation 
as:  

"Empirical equation and the coefficient default were determined from 
ASHRAE journal articles and other data on the effects of outdoor 
weather conditions."  

The source of the DOE-2 defaults is based on examining the 
infiltration relationships decsribed in the ASHRAE Handbook of 
Fundamentals.  

Mike  


On 19 Nov 2002, at 16:48, nuno lourenço wrote:

> 
> 
> 
> 
> In the input-output reference manual (pag 161) you give some values
> for the parameter A-Constant term coefficient, B-Temperature Term
> coefficient, C-Velocity Term Coefficient, D-Velocity Squared Term
> Coefficient. How do you obtained this values? I found my error in the
> cooling and heating loads. My values for this Parameter were "quite"
> different and I obtained very high loads.But if I put "our" values the
> loads are quite similar to those I am expecting.
> 
> Best regards,
> 
> Nuno Lourenço
> 
> _________________________________________________________________ MSN
> Messenger: converse com os seus amigos online.
> http://messenger.msn.com.br
> 
> 
> To unsubscribe from this group, send an email to:
> EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> 
> 
> 
> 
> 
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/ 
> 



========================================================
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx


To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/




 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/