[BLDG-SIM] eQUEST: Displacement Ventilation in offices

[Mark Case]

I'd take the 15-20% with a grain of salt. It all depends. 
We found that the fan energy penalty from running constant volume vs.
VAV was significant, which led the designer to modify the air
distribution system to further reduce pressure losses. Assuming
underfloor air distribution, the pressure drop in the supply ductwork
and the plenum itself may not be lower than a comparable VAV system.  If
the designer is careful about duct design and coil selection, fan
pressure may be reduced, maybe not. It all depends.
Marlin Addison and Dan Nall have a paper discussing modeling underfloor
systems. Their solution with DOE2 is somewhat complex but seems to deal
with many of the issues surrounding where the loads `appear' with
respect to the supply air.
One issue they brought up is heat gain within the underfloor plenum. No
easy answers but definitely a concern.  

Cooling via Underfloor Air Distribution:
Current Design Issues and Analysis Options: Cooling Frontiers: The
Advanced Edge of Cooling Research and Applications in the Built
Environment. 2001. College of Architecture and Environmental Design,
Arizona State University



-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com] On Behalf Of Peter
Simmonds
Sent: Monday, July 12, 2004 9:32 AM
To: BLDG-SIM at GARD.COM
Subject: [BLDG-SIM] eQUEST: Displacement Ventilation in offices


What you are doing is in the generally correct direction. I wouldn't
remove the lighting load from the equation just set the percentage of
heat going to the plenum at say 50%. I would calculate the ESHG for a
typical space and use the space operating temperature from the ESHG
calculations for the space operating temperature in DOE 2. Make sure the
supply temperature is 63F and check the calculated return temperature.
Don't forget to reduce the static pressure of the AHU down to about 2"
external. Compared to a conventional VAV your supply air volume will
increase but fan power will be reduced. You can also reset the chilled
water supply temperature to say 48F which will decrease chiller energy
consumption. You overall results should be about 15-20% less than a
conventional VAV.

Peter Simmonds Ph.D.
Associate,
IBE Consulting Engineers
5910 Lemona Ave. 3rd Floor
Van Nuys, CA 91411
USA
tel: 818-947-0000 #246
fax: 818-947-0047
Mobile USA: 818-219-1284
Mobile Europe: +44-7947-837-588
 
e-mail: peter.simmonds at ibece.net
 

-----Original Message-----
From: Gerald Pde [mailto:geraldpde at yahoo.com] 
Sent: Friday, July 09, 2004 3:02 PM
To: BLDG-SIM at GARD.COM
Subject: [BLDG-SIM] eQUEST: Displacement Ventilation in offices

Hi All,
I am looking for a method for modeling displacement
ventilation in offices using eQUEST.
I could set supply air higher then the conventional
hvac and also cut off heat gain from lights.
Is there more advanced modeling methods on how to
model the plume in equest.
thanks,
Gerald



		
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