[BLDG-SIM] Variable flow laboratory exhaust systems.

[Chris Jones]

Model the system as a VAV system with preheat.  Use return fans instead of 
exhaust fans.  As the system is 100% OA the return fans act as exhaust 
fans.  Set a MIN-AIR-SACH and MIN-CFM-RATIO schedules in the system to 
specify the hours when the fans run at 40%.  Use VSDs on the fans in the 
building and in the model.  This type of system has been used successfully 
at the new BC Cancer Centre for thier lab systems.  Where possible, use 
transfer air from non-lab systems to provide some of the make-up air for 
the labs - this will save considerable energy over 100% outdoor air.


At 09:24 14/04/2005, JRR wrote:
>You have no option, the fume hoods have to run 24/7/365. In 1981 
>University of Maryland College Park -- Chemistry Department had two grad 
>students recrystalize an organic compound
>using  warmed 100% N-Octane as the solvent. They wanted to speed things up 
>so they
>put the beaker in a regular refrigerator ......... The blast wiped out 
>three lab rooms on the
>4th floor. The frig did not have a sealed explosion proof defroster fan 
>motor..........
>The classrooms were empty and the two RAs got the munchies and went  the 
>basement
>vending machines for a candy bar, still the sight of their lab coats 
>riddled with glass cuts.....
>
>You can make the fume hoods a separate heating zone, supply them directly 
>with heat exchanger
>tempered outside air, and use two fan speeds occupied and vacant- hoods closed
>john ross
>
>Peter Summons wrote:
>>OK , its Friday so I am allowed to ask for advice and guidance.
>>Firstly I am using VisualDoe, I am modeling the energy performance of a 
>>200,000 sf building which has 60,000 sf of laboratories. The labs all 
>>have fume hoods so the supply air is balanced to the exhaust air (100% 
>>OA).. Now I have the following problem: a fan system is either on or off, 
>>therefore the lab fans are on 24 hours a day. I would like to reduce the 
>>exhaust flow during unoccupied periods to exhaust air from the fume hoods 
>>at their minimum flow of 40%. Reducing the flow would also reduce the 
>>make up of outside air to balance the flow and obviously reduce energy 
>>consumption.
>>Am I missing something here or does anyone have a magic trick that will 
>>allow me to accomplish my goal. Simply said HELP
>>Peter Simmonds Ph.D.
>>Associate
>>IBE Consulting Engineers
>>14130 Riverside Drive Suite 201
>>Sherman Oaks, CA 91423
>>p:   (818) 377-8220
>>f:    (818) 377-8230
>>m:  (818) 219-1284
>><BLOCKED::http://www.ibece.com/>IDEAS FOR THE BUILT ENVIRONMENT
>>
>>This e-mail message, including any attachments, is for the sole use of 
>>the intended recipient(s) and may contain confidential and privileged 
>>information. Any unauthorized review, use, disclosure, or distribution is 
>>prohibited. If you are not the intended recipient, please contact the 
>>sender by reply e-mail and destroy all copies of the original message.
>>
>>
>>
>>======================================================
>>You received this e-mail because you are subscribed
>>to the <mailto:BLDG-SIM at GARD.COM>BLDG-SIM at GARD.COM mailing list.  To 
>>unsubscribe
>>from this mailing list send a blank message to
>><mailto:BLDG-SIM-UNSUBSCRIBE at GARD.COM>BLDG-SIM-UNSUBSCRIBE at GARD.COM
>>
>
>
>
>======================================================
>You received this e-mail because you are subscribed
>to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
>from this mailing list send a blank message to
>BLDG-SIM-UNSUBSCRIBE at GARD.COM


Chris Jones, P.Eng.
14 Oneida Avenue
Toronto, ON M5J2E3
Tel. 416 203-7465
Fax. 416 946-1005 

======================================================
You received this e-mail because you are subscribed 
to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe 
from this mailing list send a blank message to 
BLDG-SIM-UNSUBSCRIBE at GARD.COM
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20050415/99345024/attachment-0002.htm>