[BLDG-SIM] Simulation of Demand Controlled Ventilation

[Steve Gates]

In DOE-2.2, the values in the MIN-AIR-SCH should not be a repeat of the occupancy schedule, but should instead be the product of the occupancy schedule times the normal minimum outside air ratio.  For example, consider a system designed for 25% outside air.  At 100% occupancy, the value in the MIN-AIR-SCH should be 1.0*0.25 = 0.25.  At 20% occupancy, the value should be 0.2*0.25 = 0.05  

This schedule does not override the economizer operation; it simply establishes the minimum outside air fraction.  

Note that, while a minimum outside air ratio of 0.05 may be sufficent to dilute CO2 at low occupancy levels, the building may have other internal sources of air pollution, such as carpet outgassing, that may require that the outdoor levels always be kept above some minimum.  This is particularly true when the building is new, or when the building has been rennovated.

I suggest you set up an hourly report looking at total supply airflow and the outside airflow to confirm the program is modeling as you intended.


  ----- Original Message ----- 
  From: Varkie Thomas 
  To: BLDG-SIM at gard.com 
  Sent: Thursday, March 20, 2003 12:10 PM
  Subject: [BLDG-SIM] Simulation of Demand Controlled Ventilation


  In order to vary the outdoor air with occupany (with CO2 sensors in the return air that controls the OA dampers), I repeated the occupancy schedule in the MIN-AIR-SCH also.  The energy use went up compared to the same input (which also specified airside economizer) that did not have MIN-AIR-SCH.  I assume the schedule was applied during the intermediate season also when it should be using 100% OA.  In this situation the OA must vary independently of the supply air which would be based on the cooling load in a VAV system

  Varkie.

    -----Original Message-----
    From: Aulbach, John [mailto:JAulbach at semprasolutions.com]
    Sent: Thursday, March 20, 2003 12:16 PM
    To: Varkie Thomas; BLDG-SIM at gard.com
    Subject: RE: [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 



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