[Equest-users] EMS Control System Modeling

[Paul Diglio]

I never heard of DCV implemented with cycling fans.  Per 90.1 and our CT State 
Code the fan needs to run continuously when the space is occupied.  Most codes 
require compliance with  90.1 whether we are modeling to that standard or not.

How can you provide the necessary ventilation air if you do not know how long 
the fan will run each hour?  Do you model the fan to run 3 times per hour and 
bring in additional ventilation air so that the hourly average meets 62.1 
standards?

My experience is with modeling DCV in both eQuest and using exceptional 
calculations via Excel.  I have verified the energy savings after the DCV 
measure has been installed.  You might expect a 6-8% savings in cooling and 
heating energy attributed to the air handling units that have implemented this 
measure.  Often the simple payback is over 5 years because DDC CO2 sensors are 
expensive. Of course, it depends on the unit size and the occupancy load.

Paul Diglio





________________________________
From: Charles Welch <cwelch at capitalreviewgroup.com>
To: equest-users at lists.onebuilding.org
Sent: Fri, March 11, 2011 2:14:17 PM
Subject: Re: [Equest-users] EMS Control System Modeling

 
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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>
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