[Equest-users] Cooling Increase DCV and ERV Measures

[Daniel Knapp]

I don't know if this is relevant to your situation, but we recently ran into a problem where turning on DCV increased the OA intake for a VAV system.  The model is at an early design stage for core and shell and the OA hasn't been specified yet so we were using eQuest OA autosizing.  The OA without DCV was sized to meet the critical zone requirement at the full design supply flow rate.  When using DCV, the OA is sized to meed the critical zone on an hour-by-hour basis, and as the supply flow rate drops, the outdoor air requirement can go up if the OA fraction for the critical zone approaches 1 leading to an increase in overall OA.  Lesson learned: don't rely on eQuest to autosize the OA as it does the OA sizing against the full design supply flow rate which may not be the worst case condition. 

Cheers,
Dan

—
Daniel Knapp, PhD, P Phys, LEED® AP O+M
danielk at arborus.ca

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca
76 Chamberlain Avenue 
Ottawa, ON, K1S 1V9 
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740




On 2013-05-30, at 10:23 PM, Netty Nina <nnina at ers-inc.com> wrote:

> Hi eQuesters,
>  
> The next two questions have been asked on here multiple times, but I have scourged the list and haven’t found a resolution. My building is a school in New England.
>  
> I have a DCV measure that shows an increase in cooling. My thought is that DCV is taking precedence over the economizer. Is there a way to force eQuest to have economizer priority or is there another issue going on?
>  
> The other issue is in the Heat Recovery. It also shows an increased cooling load for the building. I tried setting it on an ERV Schedule and limiting it to the heating season. I tried playing with the different controls. I know it’s not due to the increase in fan energy needed since the majority of units already have ERVs, but the efficiencies are better than code (and I also tried messing with the fan energy). Someone on the bldg-sim list even suggested controlling the ERV with Exhaust DT and increasing the delta-T to 20F.
>  
> I couldn’t get any suggestions to work.  How can I avoid overheating? Or is there another issue?
>  
> Thanks in advance for any help you can give me.
>  
> Sincerely,
>  
> Netty
>  
>  
> Netty Nina, LEED® AP BD+C
> Project Engineer
> ERS
> 120 Water Street, Suite 350
> North Andover, MA 01845
>  
> Ph: 978-521-2550 ext. 224
> Fax: 978-521-4588
> nnina at ers-inc.com
> www.ers-inc.com
>  
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG