[BLDG-SIM] Variable flow laboratory exhaust systems.

Graham & Megan hamnmegs at ozemail.com.au
Fri Apr 8 14:16:41 PDT 2005


Peter S,
The only thing I would add to what has been said is stating the obvious, that fume hood exhaust diversifies across a building and through the day so a single system OA schedule is likely sufficient rather than attempting something zone by zone.  Where we had a case of VAV fume hoods, we assumed an average use (50%) and then ran sensitivity studies to bound the likely performance ...  At the time this worked for us.
Regards,
Graham
----- Original Message ----- 
  From: Peter Alspach 
  To: BLDG-SIM at GARD.COM 
  Cc: Building Sim Email (bldg-sim at gard.com) 
  Sent: Saturday, April 09, 2005 5:43 AM
  Subject: [BLDG-SIM] Variable flow laboratory exhaust systems.


  Peter,

  I don't have VisualDOE, but in eQuest at the zone level you can set a min. flow schedule. You could use this to emulate the 2-position flow you desire. During the day the min. flow would be 1 (full design) and at night it would be 0.4. The SA flow rate should only go higher than the min. flow if the load requires it, doubtful for the labs under either condition. If memory serves me those commands are also available in 2.1E. With this and a VFD fan you can simulate variable position hoods and even cover a mix of CAV and VAV labs.

  Peter



------------------------------------------------------------------------------
  From: postman at gard.com [mailto:postman at gard.com] On Behalf Of Peter Simmonds
  Sent: Friday, April 08, 2005 9:25 AM
  To: BLDG-SIM at GARD.COM
  Subject: [BLDG-SIM] Variable flow laboratory exhaust systems.


  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
  IDEAS FOR THE BUILT ENVIRONMENT

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