[Equest-users] Unexpected Custom SHGC Results

[CleanTech Analytics]

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 LBL window does glass U-value not shading, ware-as LBL optics
can be used for film coefficients and used to create a custom glass type in
window, but do not do any calculations for "shading"

I say you try the same model in Energy Plus or TRNSYS and see if the
results differ.


*Jeremiah D. Crossett*
*CleanTech Analytics*
*503-688-8951*
*www.cleantechanalytics.com* <http://www.cleantechanalytics.com>


*

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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.
>
> Liam
>
> ------------------------------
> 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
>
>
> Hello,
>
> 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,
> Pete
> San Jose, CA
>
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