Modeling Questions

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A few questions I have regarding my trace model:

1) If a space have several fan coil units served by a chiller, do I
have to create each FCU as a separate system? (i.e. FCU-1, FCU-2,

2) The building I'm modeling has a hot water boiler that pretty
much runs year round with a relatively flat natural gas profile (reheat
coils, etc)....but Trace seems to be simulating boiler system heating
with a typical heating season profile (winter peaking). How do I model
this so that it reflects boiler operation year round (to coincide with
actual natural gas bills)?

Thanks in advance.


James Pagliaro, CEM, CMVP, LEED AP

Jim Pagliaro's picture
Joined: 2011-10-01
Reputation: 1

I am not a Trace expert but I will say that Energy Modeling does not work
so well on existing buildings- as actual utility bills are hard to match
with any of the software currently available.

*Jeremiah D. Crossett*

CleanTech Analytics's picture
Joined: 2012-02-09
Reputation: -1

Yes. If you are modeling an existing system, then yes each FCU is a separate System. You'd do the same if it were PTACs in a hotel. You can however, combine all the similar spaces onto one FCU, and place the coil in the Room as opposed to the system.

Best of luck getting the loads to match actual. At best you can be 85% accurate, so aim for the best that you can put into the model, but don't expect 100%. I'm also saying don't give up on getting as close as possible. Are you running Full Year 8760hrs models with the corrected weather profile imported in? Do you agree with the equipment loading/unloading graphs?

Be Sustainable -- Never let today use up tomorrow!.

Bobba_Fett's picture
Joined: 2010-10-01
Reputation: 229