[Equest-users] EMS Control System Modeling

[Charles Welch]

Thank you very much to those who helped me out with this... Finally made some good headway.

Quick question....

Modeling the DCV for my location (AZ) I shows only a very small improvement in energy consumption for my HVAC, does this sound correct?
I have always been "led to believe" by the local control companies that DCV is a huge improvement?
Myth, sales "exaggeration", or have some of them found a way to control the DCV in a manner that I am not modeling correctly? 
Opinions or pointers appreciated.

----- Original Message ----- 
  From: Karen Walkerman 
  To: MatthewRLarson at eaton.com 
  Cc: GCollins at glumac.com ; cwelch at capitalreviewgroup.com ; equest-users at lists.onebuilding.org 
  Sent: Wednesday, March 09, 2011 2:48 PM
  Subject: Re: [Equest-users] EMS Control System Modeling


  Regarding DCV there are a few things to know:



  1.  demand is based on the number of people in the space and the outdoor air per person specified at the zone level.  If your outdoor air rate is not entered as a per person air rate, then DCV will not work properly


  2.  If your fans are not constant volume, ie they can cycle or they are variable speed, then you need to make sure that the proper ventilation air is supplied in your base case.  Usually, I set the fan flow to 'variable'.  If, in reality, the fans cycle on and off, I change the fan curve to linear.  Then, i set the minimum flow to be equal to the outdoor air rate fraction.  Otherwise, implementing DCV can actually RAISE energy.


  On Wed, Mar 9, 2011 at 10:59 AM, <MatthewRLarson at eaton.com> wrote:

    Charles,



    Regarding the DCV, you need to specify the “Minimum OA Control Method” under the Outdoor Air tab for the system to state whether the CO2 sensor is in the return or in the space.  Then at the zone level, specify the “Minimum Flow Control” under the Air Flow tab to state if the minimum OA resets up or down depending on occupancy level.  To ensure the amount of OA going into a space doesn’t go below the ASHRAE 62.1 minimum, I always input the OA Flow per Person and/or Flow per Area at the zone level as well.  DCV has always been something I’ve been a little dicey about so any additional suggestions/comments would be great.



    Thanks,



    Matthew Larson, LEED AP BD+C
    Project Engineer

    Energy Solutions Group

    E M C Engineers, Inc.
    Eaton’s Electrical Services & Systems 
    143 Union Blvd, Suite 350
    Lakewood, CO 80228
    tel: +1 303 328-3419
    mobile: +1 303 668-2511
    fax: +1 303 974-1239

    MatthewRLarson at Eaton.com 
    www.eaton.com/energysolutions  





    From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Greg Collins
    Sent: Tuesday, March 08, 2011 5:53 PM
    To: Charles Welch; equest-users at lists.onebuilding.org
    Subject: Re: [Equest-users] EMS Control System Modeling



    Charles - A quick suggestion for the setback is to try setting your system fans to "cycle on any."  Otherwise, your system might not kick on to maintain setback temperatures. 



    Greg Collins
    GLUMAC | (949) 833-8190



    From: Charles Welch [mailto:cwelch at capitalreviewgroup.com] 
    Sent: Tuesday, March 08, 2011 4:24 PM
    To: equest-users at lists.onebuilding.org
    Subject: [Equest-users] EMS Control System Modeling



    I am doing an quick estimate for adding EMS control to an existing HVAC system (schools) which incorporate the following measures



    1)    Automatic thermostat setbacks for building occupation

    2)    Demand controlled ventilation

    3)    Economizers



    Here are my "challenges"
    1)    Simulation with setback temperatures shows no reduction in energy

    2)    I am unsure how to handle DCV

    3)    Simulation with economizers show very little reduction



    I would appreciate any pointers, suggestions, etc. on what to do here.

    I would especially appreciate any example files to see how you input the data to get proper results.





    Thanks in advance for any help.

      




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