[Equest-users] Unexpected Custom SHGC Results

[Joe Huang]

I totally agree. The suggestion that eQUEST is flawed in modeling such a basic heat transfer process as solar gain through windows is extremely unlikely. My experiences in doing such parametrics with DOE-2 over many years if not decades is not that the program  is wrong, but that it's considering many other factors often overlooked in a simplistic view of things. Chief among these are the sizing of the HVAC system, its configuration, and operations. At the bare minimum, you should make sure that you input the same system size in both runs. Furthermore, in a mild climate like San Jose, something as innocuous sounding as COOL-CONTROL=WARMEST can cause havoc in the expected savings. In all the runs I've looked at, there was always an explanation when the results  do not meet or run counter to the original expectations. In fact, I regard those as the most valuable instances for using building energy simulations.  After all, if all you want is confirmation of your back-of-the-envelope estimates, why do a simulation at all? Just do a degree-day calculation instead.

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Joe Huang
White Box Technologies
346 Rheem Blvd Suite 108D
Moraga CA 94556
(o) 1(925)388-0265
(c) 1(510)928-2683
yjhuang at whiteboxtechnologies.com

On Jul 15, 2012, at 5:53 PM, Chris Jones <cj at enersave.ca> wrote:

> I can think of a number of reasons why you might see an increase in cooling and fan "load".  Without spending some time looking at the input/output, it is pretty hard for me to offer any definite opinion.  I know for myself, it is generally an input assumption I hadn't considered, not a flaw on the modelling program.
> 
> For doing analysis on an existing building, you want to make sure your inputs are not defaulting and that the model somewhat matches the building.
> 
> 
> 
> At 02:51 PM 14/07/2012, Peter Baumstark wrote:
>> 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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> >>
> Christopher Jones, P.Eng.
> Suite 1801, 1 Yonge Street
> Toronto, ON M5E1W7
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