Dear all:

My project is a 84- floor super-high building with 27 floors for
office and 47 floors for residential(hotel and apartment) and others for
retail and equipment floors. When I select baseline HVAC system I?m confused
as both the two option below sounds rational:

1) The Note under TABLE G3.1.1A- Baseline HVAC System Types in Page
181 of ASHRAE 90.1 tells that : ?Where attributes make a building eligible
for more than one baseline system type, use the predominant condition to
determine the system type for the entire building.?

2) The explanation in Page G-23 of ASHRAE 90.1 MANUAL tells that : ?If
a building has both residential and nonresidential spaces with their total
conditioned floor area both greater than 20,000 ft?, for instance a
residential tower with retail and restaurants at the base, then the HVAC
system type is determined separately for the residential and nonresidential
portions.?

So if I follow option 1 I should select PTAC for the whole building which I
think unsuitable. else if I follow option 2 I should select PTAC for
residential and VAV for office and others.

Which option should I follow?

Could anyone tell me? Thanks

Zhiren ZHOU