Interpretation of Table G-A in ASHRAE 90.1 2007

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I have an "intermediate" sized building (25,000 to 150,000 sqft) with
several systems in it. can each system be determined separately or should
each by a System type 5/6 depending on Heating source? I would like to
label some small systems as a type 3/4 and some as type 5/6 depending on the
area that is served by the system.

thanks for any opinions that people would like to share.

Rob Hudson

rdh4176's picture
Joined: 2011-02-14
Reputation: 0

Hi Rob,

If the systems serve distinctly different uses that comprise more than
20,000 sf you are fine. Otherwise, I would use the predominant heat source.
It will be interesting to hear others opinions.


cmg750's picture
Joined: 2010-10-05
Reputation: 0

Exception a of G3.1.1 looks at your proposed systems and has the noted 20,000 sf criteria.
Exceptions b & c are tied to thermal zones and are not tied to your proposed system configuration.
The planned system boundaries alone are not sufficient to trigger a separate lookup in table G.3.1.1A.
Often the mapping of system to zones is different between proposed and baseline model.
Paul Riemer

Paul Riemer's picture
Joined: 2011-09-30
Reputation: 0