[Equest-users] Unexpected Custom SHGC Results

Paul Diglio paul.diglio at sbcglobal.net
Sun Jul 15 17:02:50 PDT 2012


I agree.  I find the comment to be more than mildly offensive.  

I have the same experience that funky modeling results usually are the result of 
flawed inputs or depending on too many eQuest defaults.

 Paul Diglio, CEM, CBCP

87 Fairmont Avenue
New Haven, CT  06513


From: Joe Huang <yjhuang at whiteboxtechnologies.com>
To: CleanTech Analytics <jeremiah at cleantechanalytics.com>
Cc: equest-users at lists.onebuilding.org
Sent: Sun, July 15, 2012 7:21:54 PM
Subject: Re: [Equest-users] Unexpected Custom SHGC Results

I've found this comment to be mildly offensive as well as showing a     lack of 
understanding about how heat gains ultimately get translated     to cooling 
energy consumption.  It's extremely hard for me to     believe that eQUEST or 
DOE-2 has been flawed for 25 years in     modeling something as fundamental as 
solar heat gain through     windows.  In all the decades I've used DOE-2 to 
analyze window     performance for DOE's EnergyStar Program as well as numerous 
other     projects, whenever the results did not match or ran counter to     
first-principle expectations, it was always because there was some     other 
factor that have been overlooked or ignored, chief among them     being the size 
of the HVAC system, its configuration, and control     strategy.  Locations with 
mild cooling loads, such as San Jose,  are     particularly sensitive to such 
system interactions.  Were both runs     done using "autosizing"?  What
kind of a system was modeled - VAV or CAV ?   Did the model have an     
economizer?   What were the HEAT-CONTROL and COOL-CONTROL strategies     ?  
etc.   It's far too early to lay blame on the DOE-2 algorithms.


On 7/14/2012 1:41 PM, CleanTech Analytics wrote: 
Just           admit it- eQuest is flawed, you don't have to make up things           
to protect it-  

>If it is a             mistake to use the percent points rather then percent             
>reduced from the abrataty eQuest assumption from 1999 window             specs 
>than the it should have reduced solar heat gain by             more then his 
>product even provided- Using the 33 percentage             points but used the 
>33% should have provided him over stated             cooling reduction, (and 
>extra added heating consumption             tradeoff) 
>O-             and FYI LBLwindow does glass U-value not shading, ware-as 
>LBLoptics can be             used for film coefficients and used to create a 
>custom glass             type in window, but do not do any calculations for 
>I say you             try the same model in Energy Plus or TRNSYS and see if the             
>results differ.
>Jeremiah D. Crossett
>CleanTech Analytics
>This document may contain                     valuable information proprietary 
>to CleanTech                     Analytics which is private and confidential. It 
>may                     not be shared, copied, stored or transmitted in any                     
>form without the prior written consent of CleanTech                     
>On Sat, Jul 14, 2012 at 12:42 PM,             Liam O'Brien 
><obrien_liam at hotmail.com> wrote:
>Hi Pete, 
>>I don't have a ton of experience with detailed                     modelling of 
>>shades in eQUEST, specifically, but two                     things that could be 
>>at play:
>>- The claim from the manufacturer sounds like                     it's not 
>>intended to universal in absolute terms.                     Also, it would be 
>>more conservative to reduce the                     SHGC by 33 percent than                       
>>33 percentage points(as you did) if you're going to take                       
>>this simplified approach. Therefore, it would be                       closer to 
>>SHGC=0.44. Subtle but significant. You                       could try using 
>>software that specializes in                       window/shade performance like 
>>LBNL Window or                       Parasol to try to characterize the 
>>performance of                       your specific shade-glazing combination
>>- Depending on the operating conditions and                     construction of 
>>the building, there's a chance your                     results 
>>aren't ridiculous. If shades intercept                     transmitted solar 
>>radiation, then a lot of that                     energy will almost immediately 
>>transfer to the air                     via convection. If you have thermally 
>>massive                     interior surfaces, there's a chance your building                     
>>could actually perform better without those shades                     because 
>>the air conditioning won't kick in till                     later. 
Date: Sat, 14 Jul 2012 11:51:02 -0700
>>From: pbaumstark at sbcglobal.net
>>To: equest-users at lists.onebuilding.org
>>Subject: [Equest-users] Unexpected Custom SHGC                       Results 
>>I have an "L" shaped building with the                               point of 
>>the "L" facing North.  The inside                               of the "L" has 
>>both NE and NW surfaces,                               that include a high 
>>amount of glass, which                               heats up the perimeter 
>>building spaces                               considerably during the summer.  
>>Glazing                               is single pane tinted.
>>The customer wants to install some Verisol                               
>>SilverScreen shades in these windows.                                According 
>>to the manufacturer, the SHGC                               will reduce by about 
>>33%.  I modeled in                               eQUEST, window properties in 
>>these windows                               to have an SHGC of 0.67 and ran an 
>>EEM                               reducing SHGC to 0.34, and got an increase                               
>>in cooling load and fan load year round,                               even in 
>>the summer months.
>>Am I seeing this wrong?  I can't figure                               out how I 
>>could possible get results like                               this?
>>Thank you,
>>San Jose, CA
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Joe Huang       White Box Technologies, Inc.       346 Rheem Blvd., Suite 108D       
Moraga, CA 94556       (o) (925)388-0265       (c) (510)928-2683 
www.whiteboxtechnologies.com "Building energy simulations at your fingertips"
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