[bldg-sim] how much cold air infiltration can I really expect?

[David S Eldridge]

Aaron, are these buildings in design phase, or are you modeling existing
buildings?
 
If existing, I'd suggest getting everything into the program as best you
can first, and then adjusting the infiltration parameters last until you
match whatever calibration data you have.
 
For buildings in the design phase it is difficult since the future
infiltration may depend upon many variables, including the quality of
the contractor and operations of the building which you can only
estimate at this phase.  While we understand the causes of infiltration
and the variables you mention that affect it, infiltration is still hard
to quantify based on values of factors that you don't know and whether
or not the weather data that you do have is representative concerning
wind variables.
 
One solution is to choose some moderate value.  Then you could vary that
value by +/-some percentage and see if the "answer" you are looking for
from the energy simulation changes depending on the values.
 
Hope this helps!
 
David
 


________________________________

	From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of
Dahlstrom, Aaron
	Sent: Wednesday, January 31, 2007 8:29 PM
	To: bldg-sim at gard.com
	Subject: [bldg-sim] how much cold air infiltration can I really
expect?
	
	
	I have noticed that infiltration makes up most of the winter
heating load for several high-bay single-story commercial buildings I'm
modeling. (big-box retailer, light manufacturing facility)
	 
	I've used a variety of methods - ACH estimates, CFM / so of
facade (per ASHRAE F27.10), and Area(crack) x Velocity(winter wind) - to
estimate infiltration.
	 
	Have other people stuck with these methods? Or does anyone know
of better ways to estimate infiltration?
	 
	Aaron Dahlstrom
	AKF Engineers, LLP
	1500 Walnut Street, Suite 1400
	Philadelphia, PA 19102 
	Phone:   (215) 282-2169
	Fax:        (215) 735-6706
	www.akf <http://www.akf-engineers.com/> -engineers.com



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