[Equest-users] UA Convergence Error, Design Days and Simulation Speed

[Paul Diglio]

Hi Melanie:
I thought everyone would like to know that in addition to helping resolve my convergence issues, by putting in cooling and heating design days my project simulates much faster.
Before, the simulation meter would go up to 185% before it was complete, and with the CDD and HDD defined, the simulation completes at 105%, which takes about half the time.
Thank you,

Paul Diglio
87 Fairmont Avenue 
New Haven, CT 06513 

203-415-0082 

    On Wednesday, December 11, 2019, 1:43:45 PM EST, Melanie Stachowiak <mgstachowiak at meengineering.com> wrote:  
 
 
Paul,
 
Go to project & Site and set up design degree days if they aren't already in there (one for cooling, one for heating). If you've already created them, just adjust the number of degree days. You can also isolate to a single hour if you wish instead of having a high or low. Looks like it was my cooling design degree day that was causing the problem. I still have my heating degree day set up for seven days. This was set up for Buffalo NY (ASHRAE climate 5A), so your values might be different depending on your location.  
 
See screen clips below.
 
~Mel
 
  
 
                 
 
  
 
  
 
Melanie G. Stachowiak, P.E., LEED AP BD+C, CMVP
Project Manager, Sustainability/Commissioning Services Group

M/E Engineering, P.C. 
Suite 320, 60 Lakefront Boulevard
Buffalo, NY 14202
716.845.5092 x1207 | C: 716.830.7038 
mgstachowiak at meengineering.com
www.meengineering.com


 
  
 
From: Paul Diglio <paul.diglio at sbcglobal.net>
Sent: Wednesday, December 11, 2019 1:09 PM
To: Melanie Stachowiak <mgstachowiak at meengineering.com>
Subject: Re: [Equest-users] UA Convergence Error
 
  
 
Hi Melanie:
 
  
 
I appreciate the response.  How do you set the design degree days to a single day?
 
  
 
Thank you,
 
  
 
Paul Diglio
87 Fairmont Avenue 
New Haven, CT 06513 

203-415-0082
 
  
 
  
 
On Wednesday, December 11, 2019, 11:05:55 AM EST, Melanie Stachowiak <mgstachowiak at meengineering.com> wrote:
 
  
 
  
 
Hi Paul,
 
I had the same problem recently.
 
The way I cleared it was playing with the design degree days - setting them to a single day.
 
 
 
I'm still not clear why eQuest has this issue, identifying it as a heat exchanger convergence issue when it's clearly an airside system error. 
 
 
 
We seem to be getting a lot of errors related to the design degree day choice, and the choice of the day/hour/duration seems to alter the results of the model which is really unsettling. We've had many internal discussions about if we should be using climate data for the design degree day or building peak. Still undecided.
 
 
 
I know this doesn't help explain why you're getting the UA convergence error, but at least it should help clear it.
 
 
 
~Mel
 
 
 
Melanie G. Stachowiak, P.E., LEED AP BD+C, CMVP
Project Manager, Sustainability/Commissioning Services Group

M/E Engineering, P.C. 
Suite 320, 60 Lakefront Boulevard
Buffalo, NY 14202
716.845.5092 x1207 | C: 716.830.7038 
mgstachowiak at meengineering.com
www.meengineering.com
 
  
 

 
 
   
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