Infiltration baseline for modeling

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Hi all,

If I'm using Ashrae 90.1 2004, where building leakage hasn't been
defined yet, what should a 'baseline' level of infiltration be? Any
thoughts / experience with this?

Jim Crockett, P.E.

Crockett, Jim's picture
Joined: 2011-09-30
Reputation: 0


I am not a modeler, but I interacted with the experts at TRANE using a
demo package they provided me.

I told them I wanted to use one of their building design templates and
change only the parameter for infiltration. We used an elementary
school in Wisconsin with a CMU back-up wall and brick cladding. TRANE
showed me where the default air leakage parameter for that building
design template was located, and they showed me how to change it to
match the air leakage rate called out by the Air Barrier Association of
America. We ran the model before and after, and it showed a 58%
decrease in natural gas consumption and a 22% decrease in electricity
consumption. Right in line with the NIST study. They confirmed to me
that no matter what design was created for the model, a default air
leakage rate would be generated by the software.

Paul Grahovac, LEED AP

Paul Grahovac's picture
Joined: 2011-10-02
Reputation: 0


I would draw your attention to the following resources:

The Air Infiltration & Ventilation Centre (AIVC) - great set of reading
resources for this sort of stuff - my PhD and subsequent work has loads of
references that are held by their central library.

Also worth checking out the International Journal of Ventilation, useful
stuff there too:

Edited by essentially a who's who of ventilation research, it's an excellent
resource, albeit very academic based. Also has a useful online combined
natural & mechanical ventilation calculation tool :

Also worth using the tables in the CIBSE Guide A.

Hope this helps.

Dr Paul Carey

Paul Carey's picture
Joined: 2011-10-02
Reputation: 0

Dear Paul,

I was very interested by your email and want to enquire whether, in the
TRANE model, they define a fixed assumption of air leakage rate for the
baseline building.

If so, would you know what that figure is?

Tariq Abbas's picture
Joined: 2011-10-02
Reputation: 0