We created an eQUEST model for a four-story office building with a total
area of 53,000 sq. ft for LEED certification. In the baseline model we
submitted to GBCI, we used System 5 (Packaged DX rooftop VAV w/reheat
and hot water fossil fuel boiler) as the primary system in per ASHRAE
90.1-2004 Table G3.1.1.A. At the same time, the single zone packaged
rooftop air-handling unit (PSZ) with constant volume and fossil fuel
furnace was utilized as baseline for the spaces including
telecommunication rooms and electrical rooms since they had operating
schedule and peak thermal loads significantly different from other
office spaces by more than 10 Btu/Hr.Ft2. This was in accordance with
paragraph "Exceptions to G.3.1.1" on page 170 of ASHRAE Standard
90.1-2004.

However, in the recent review comment we received from GBCI, it was
addressed that System 5 "Packaged DX rooftop VAV w/ reheat and hot water
fossil fuel boiler" should have been modeled for ALL SPACES in the
baseline. No PSZ system should have been used in the baseline model.

I am confused when the "Exceptions to G.3.1.1." of ASHRAE 90.1 - 2004
should apply if not in this case. Can anyone please share your
experience and advice?

Thank you for any comments!

Sophi Feng, PE, LEED AP