Modeling a 2 mill. sq. ft. hospital facility in Trace

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I'm modeling a very large hospital complex in Trace. The facility is
located in New Orleans, and like a hospital uses a substantial amount of
OA, and is a 24-7 operation in many areas.
Does anyone know if Trane (or any other program) can accurately model room
exhaust and OA rates? I want my OA and room exhaust to be accurate so I can
get accurate energy numbers and accurate ventilation CFM (and thus energy)
numbers. The AIA defines some rooms to be totally exhausted and does not
require OA to the rooms, of course our air handler will in reality put in
say 30% into the room, but all that air is exhausted out of the building.
Trace will reduce the exhaust rate to whatever the OA has been set to for
the room. Trace does not do a system level air balance, it balances each
individual room. This requires an engineer to use 100% OA for totally
exhausted rooms, and exaggerate the energy used for ventilation which would
be cooling, reheat, and fan energy, or you can use your 30% OA and have a
reduced exhaust rate - if you are using say .. a total energy wheel, your
out of luck because now you've reduced your exhaust CFM...

Is there any program that models this accurately? I've been told to use
Trace's adjacent air transfer feature - it does not work. I've tried this
on a small file, and also on a patient tower with 600 rooms. This feature
does not transfer air across a whole system and is terribly cumbersome to

This is just one problem I'm having with Trace, there are many others, I'm
seriously considering going to E+, Designbuilder, or VE...
Anyone else fedup with Trace?

Oh - another issue - anyone try modeling airborne isolation rooms which are
on different AHU's but are connected to one common exhaust fan? I figure I
could go through and add up the CFMs for the individual rooms and manually
size the thing, but again I'm looking for energy..

Shariq Ali, LEED AP

Shariq_Ali at's picture
Joined: 2011-10-01
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