[Equest-users] Delta-Delta-Delta

[Joe Huang]

Results change for all sorts of reasons, even if there has been no change in the fundamental algorithms. For example, there was a sizable shift from heating to cooling loads going from DOE-2.1B to 2.1C, which I traced to a change in the defaults for neighborhood-terrain-factors that changed the local wind speed, hence higher air-film-coefficients, more radiative heat gain going into the space, etc. If you're puzzled why numbers have changed, I would recommend looking through the documentation on what bug fixes and changes have been noted, and thinking  through how they might affect the numbers. I know that could be tedious and frustrating, but I know of no other way, because even the developers might not be aware of all the knock-on effects. I'm not sure averaging results from various versions of the same program gets you the most reliable results. I assume that overall bug fixes are intended to improve the program!


Sent from my IPad

Joe Huang


On Apr 8, 2014, at 8:12 AM, Melissa Crowe <MCrowe at engsolutions.com> wrote:

> John
> 
> I do know that  5% error is well within all the other assumptions I have made, and in the end it is a comparative analysis, but I assumed that since both versions of eQuest are driving the same DOE2 engine I expected the same results.
> 
> Thanks for historic reference... at least it doesn't take as long to run as it would have on my old "trash"80!
> Melissa
> 
> -----Original Message-----
> From: John Aulbach [mailto:jra_sac at yahoo.com]
> Sent: Tuesday, April 08, 2014 10:58 AM
> To: Nick Caton; Kevin Kyte; Kathryn Kerns; equest-users at lists.onebuilding.org; Melissa Crowe
> Subject: Delta-Delta-Delta
> 
> Melissa:
> This may come as a shock, but I have had the privilage of runniing DOE2 since the cave man days (1984). Every version (DOE 2.1 A, B, C, D, E, and eQuest 3.55, 3.60 thru 3.64,have ALL had different results !!!!
> This isnt one of God's 10 Commandments, its an energy estimation program. I am sure if you compare delta energy usage between windows, the Deltas between the two programs will be similar.
> And in the end, who will know you don't have the 100% best glass, as you will have have built the best buildng, and not the inefficient one.
> And I agree on your 3.64 decision.
> 
> ----------
> Sent from AT&T's Wireless network using Yahoo! Mail
> 
> ------Original Message------
> From: Melissa Crowe <MCrowe at engsolutions.com>
> To: "Nick Caton" <ncaton at smithboucher.com>,"Kevin Kyte" <KKyte at watts-ae.com>,"John Aulbach" <jra_sac at yahoo.com>,"Kathryn Kerns" <kathryn.kerns at bceengineers.com>,"equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
> Date: Tuesday, April 8, 2014 10:33:36 AM GMT-0400
> Subject: RE: [Equest-users] eQUEST v3.65 build 7163 released Mar 18 2014        -       fixes   hourly report viewer
> 
> 
> 
> After this discussion I have decided to retreat to 3.64.  I have done so with a current project, the results of the two versions were not the same!   On comparing  the sim files I see that the versions do not agree in their calculation of wall conduction, glass conduction or glass solar.  The total building peak is 5% higher in 3.64  mostly due to the glass conduction component.   I imported the inp file and even used the 3.65 TMY3 in case the file had been updated.    The particular project is a window  study so this is a bit troubling.
> 
> The Summary of eQUEST Changes & Fixes for 3.65 reports updating film properties import from Window in 3.65 but no change in the calculation algorithm.
> 
> Has anyone else seen discrepancy in end-use energy results?
> 
> [cid:image002.jpg at 01CF5314.E58C1D10]
> Melissa P. Crowe, LEED AP
> Project Engineer
> Engineered Solutions, Inc.