[BLDG-SIM] DOE-2/eQUEST Exhaust Flow & Outdoor Air Warning

Andy McNamara andyjmc at gmail.com
Mon Aug 27 12:58:16 PDT 2007


Hello,

I am creating an eQUEST baseline for a multifamily residential building in
New York City.  As such, all the HVAC systems are set to PTAC and as per NYC
building code, the ventilation rate is set ~3 times as high as ASHRAE 62.  I
receive warning messages in the SIM file for each system (see below for a
representative warning message).  I am not sure what eQUEST is trying to
tell me, but I suspect that it is saying that it has increased the amount of
outdoor air intake in order to equalize that with the unusually high exhaust
CFM specified.  I pasted the language from DOE-2 help on "EXHAUST-FLOW"
below.  Can anyone confirm or deny if my suspicion is correct?

Thanks in advance for your help.

Best,
Andy


 **WARNING**********************************************************************
             ZONE EL1 NW Perim Zn (G.NW6)          in SYSTEM EL1 Sys1 (PTAC)
(G.NW6)
             has unused EXHAUST-CFM specified.
             This has been converted to outside air.
....

FROM DOE-2 Help:
EXHAUST-FLOW

Flow rate (in standard, or sea level, cfm) of direct exhaust from the zone.
This data entry can be omitted if there is no exhaust from the zone, or if
there is only central exhaust by way of the system return. The SYSTEMS
program does not simulate heat recovery from zone exhaust, but only from
central exhaust. If heat is to be recovered, zone exhaust should not be
entered but rather allowed to default to the central system. Return fan
static should be adjusted, on a weighted average basis, to reflect zone
exhaust fan conditions. The program will not allow MIN-OUTSIDE-AIR to be
less than the sum of EXHAUST-FLOWs for all zones divided by the sum of
supply cfm's for all zones. That is, MIN-OUTSIDE-AIR will not restrict the
operation of exhaust fans.


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