[BLDG-SIM] Simulation of Demand Controlled Ventilation

[Steve Gates]

Mostly correct; item #3 below calculates minimum outside air at design conditions, and then uses this value all hours; it does not adjust hourly for the actual number of people.
  ----- Original Message ----- 
  From: Sheila Sagerer 
  To: BLDG-SIM at gard.com 
  Sent: Thursday, March 20, 2003 1:28 PM
  Subject: [BLDG-SIM] Simulation of Demand Controlled Ventilation


  Hello,

  There are three options for values in the min-air-sch.  

  1.  A fraction value (ex:  0.36) in any given hour sets the MINIMUM air as a fraction of total system air flow for that hour.  The economizer is enabled in this case  so the actual outside air could be greater than the minimum if cooling is needed and outside conditions favor the use of the economizer.  NOTE:  Be careful, even if you set the minimum OA ratio in the system screen, you should still use that same ratio in the schedule.  Using a value of 1 will give 100% of the total system OA, not 100% of the minimum OA.

  2.  A zero (0) value closes the outside air damper AND disables the economizer.  This is usually used for optimum start periods.

  3.  A Flag value (-999) asks DOE to calculate the minimum amount of outside air needed based on the number of people in the occupancy schedule and the OA cfm/person specified in the thermal zone.  The economizer is enabled in this case so again the actual outside air could be greater than the minimum if cooling is needed and outside conditions favor the use of the economizer.  

  For demand controlled ventilation, I've used an OA schedule flagged 24/7 (except during optimum start periods = 0).  For constant OA during occupied periods and closed OA dampers when unoccupied, I use the minimum OA fraction during occupied periods, "0" during optimum start, and Flag all unoccupied hours to ensure economizer availability.

  Hope this helps.

  Sheila Sagerer
  Energy Opportunities, Inc


  -----Original Message-----
  From: postman at gard.com [mailto:postman at gard.com]On Behalf Of Aulbach, John
  Sent: Thursday, March 20, 2003 1:16 PM
  To: BLDG-SIM at gard.com
  Subject: [BLDG-SIM] Simulation of Demand Controlled Ventilation


  What does -999 do in the Min-Air-Sch? Doesn't that "vote" on what OSA is needed, and also yield to the economizer as well?
    -----Original Message-----
    From: Varkie Thomas [mailto:Varkie.Thomas at som.com]
    Sent: Thursday, March 20, 2003 9:59 AM
    To: BLDG-SIM at gard.com
    Subject: [BLDG-SIM] Simulation of Demand Controlled Ventilation


    We tried scheduling the outdoor air fraction in the Systems component of the DOE2.1E program by using the occupancy schedule in the Loads component.  This would vary the outdoor air based on occupancy using CO2 sensors in the Return Air.  However the schedule overrode the air-side economizer.  Can this problem be fixed in DOE2.1E?

    Varkie Thomas
      -----Original Message-----
      From: Bob Ramirez [mailto:bob at rer.com]
      Sent: Wednesday, March 19, 2003 4:53 PM
      To: BLDG-SIM at gard.com
      Subject: [BLDG-SIM] Simulation of Demand Controlled Ventilation


      Hello group



      Does anyone out there have experience with simulating demand controlled ventilation in DOE2?  I am especially interested in any work that validates the use of such a model for estimating energy savings from this control scheme.  Any advice or information would be greatly appreciated.  Thanks!



      Bob





      Bob Ramírez, P.E. 
      Senior Engineer 
      Bob at RER.com  , Bob.Ramirez at Itron.com 



      RER is now Itron!
      http://www.RER.com/Consulting 
      11236 El Camino Real  San Diego, CA 92130    USA

      VOICE:858.481.0081X427  FAX:858.481.7550 





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