I'm modeling a multifamily building that uses a campus plant for cooling.
I'm familiar with the USGBC document for modeling DES plants, and am
currently looking at Option 1, which is an energy neutral purchased chilled
water plant. Because the building is residential, the normal baseline
system is System 1-PTAC. The USGBC document says to change this to a 4-pipe
fan coil in order to make use of the purchased chilled water. Fair enough.

My problem is how to calculate fan power for this new baseline system. FCUs
are not a normal baseline system, so there's no direction in Appendix G.
Has anyone come across this before? If so, what did you do to calculate the
fan power?

For what it's worth, I see three options:
1) Since I'm replacing System 1, use the formula for System 1,
Pfan=CFMs*0.3. The resulting fan power is much lower than my proposed,
which is a bummer, though it's primarily due to 5 DOAS fans that of course
aren't in the baseline.

2) Allow TRACE to calculate the fan power using its built-in 90.1 features.
This number comes out much higher than the proposed fan power, which is
what tipped me off to this issue. I'm currently trying to back out how
Trace arrived at the fan power it did.

3) The proposed building uses fan coils. Since the new baseline also does,
set the fan powers equal and only receive credit from reduced run hours due
to improved envelope and such. This sounds like a nice way to guarantee
reviewer comments.

Any thoughts?

Thanks,

*Jason Kirchhoff*