[BLDG-SIM] Demand Controlled ventilation in eQuest

[Dahlstrom, Aaron]

Karen,
 
not sure I totally understand eQUEST options either... here's my shot:
 
the relevant keywords are: 
 
- MIN-OUTSIDE-AIR
- OA-SIZING-METHOD
- MIN-OA-METHOD
- MIN-AIR-SCH
 
and
 
- OA-CONTROL
 
if you search on these in the "DOE22Vol2-Dictionary.pdf" document from
doe2.com, you'll see options for OA CFM control, which include fixed
quantity, increased vent for economizer, and decreased minimum
ventilation for CO2 control.
 
Under DOE-2.1e, often the default was fixed quantity OA; I modeled DCV
by correlating a minimum outside air schedule to the occupant schedule.
 
If you look at your BDL file you can see how what defaults eQUEST is
generating and the relevant differences between your systems.
 
Aaron Dahlstrom
AKF Engineers
 

-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Karen
Walkerman
Sent: Friday, August 24, 2007 8:46 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Demand Controlled ventilation in eQuest


Hello all,
 
I'm a little confused by eQuest's options for ventilation air and
control.
 
When I specify OA-FLOW/PER, this value seems to become my minimum
outdoor air flow.  I would expect this entry to follow the occupancy
schedule and modulate with demand, or at least to have the option to
schedule the OA flow. 
 
When an economizer is specified, the total energy use drops
significantly and the loads seem to modulate with the OA flow (although
there may be some other effects going on here too).
 
Any ideas on why this happens?  Is there any way to model a
demand-controlled system that does not have an economizer attached?
 
Thanks,
 
~karen~


-- 
Karen Walkerman
Second Law Consulting
802-238-0980
kwalkerman at gmail.com 



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