Re: [EnergyPlus_Support] Ventilation/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.

Perhaps some other users have better values to offer.

Mike





On 23 Sep 2002, at 16:30, alexander.beisteiner@fh-pinka wrote:

> 
> Dear Sir/Madam
> 
> In the Input/Output reference the objects Ventilation and Infiltration
> refer to the following coefficients: Constant Term Coefficient (A)
> Temperature Term Coefficient (B) Velocity Term Coefficient (C)
> Velocity Squared Term Coefficient (D)
> 
> Where can I find typical values for these coefficients for both
> ventilation and infiltration.
> 
> Regards
> Alexander Beisteiner
> 
> ----------------------------------------------
> Alexander Beisteiner
> Forschungs- und Technologietransfer
> Pinkafeld GmbH
> Steinamangerstrasse 21
> 7423 Pinkafeld
> 
> Tel.: 0043/3357/45370-1324
> alexander.beisteiner@xxxxxxxxxxxxxxxxxx
> http://www.fh-pinkafeld.ac.at
> 
> 
> 
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