App G system type 6 story 100,000 sq ft building

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I searched thru the archives but couldn't fiind an answer to this.

Why is there a direct conflict in the required Baseline system type between the App G chart in 90.1 and the wording in the 90.1 user manual?

I have a 6-story building that is 100,000 sq ft. If I read Table G3.1.1A of 90.1, it says:

"Nonresidential & More than 5 floors OR > 150,000 sq ft", that I should use System 8 (VAV with PFP boxes).

Even Table G-A in the User Manual says the same thing.

In addition, the requirements for using System 6 say:

"Non residential, 4 or 5 floors or less than 75,000 sq ft OR 5 floors or less and 75,000 - 150,000 sq ft".

Both of these facts would lead me to believe that anything over 5 stories should be System 8. However, the wording in the User Manual goes on to say that:

"For intermediate-sized buildings that are 4 or 5 floors and less than 75,000 sq ft or more than 5 floors and between 75,000 and 150,000 sq ft, the baseline building HVAC system for electric heat is packaged VAV system."

I've finished modeling the Baseline building with System 8, but now that I've read the User Manual, it would appear that I am supposed to use PVAV. I really hope I don't have to go back and change the baseline system again.

Any thoughts?

Thanks

James Hansen

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James,

I'd stick to Table G3.1.1A and use System 8. The wording in the 2004
User's Manual looks like a mistake. The wording in the Standard
90.1-2007 User's Manual, p.G-23, is changed to, "For intermediate-sized
buildings that are 4 or 5 floors and less than 25,000 sq ft or less than
6 floors and between 25,000 and 150,000 sq ft, the baseline building
HVAC system for electric heat is packaged VAV system."

Regards,

William Bishop, EIT, LEED(r) AP

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