[Bldg-sim] eQuest - Energy consumption increasing on reducing Glass U-Value

[Joe Huang]

 From my experience, such kinds of counter-intuitive results, e.g., 
cooling energies going up with lower U-values,  are due to overlooked 
systems/loads interactions rather than arcane loads considerations such 
as spectral properties of window glazings.

The three interactions that I would look are:

(1) does the system have an economizer that vents the cooling loads when 
the indoor temperature or enthalpy exceed that outdoor ?

(2) is the system sizing the same for both runs? If not, fix the system 
size to the larger from the two autosized runs.

(3) (this gets rather arcane but explained the anomaly for increased 
heating in mild cooling climates like the Pacific Northwest) change 
Cooling Control from CONSTANT to WARMEST, i.e., control cooling control 
for the warmest zone rather than all zones.

Joe

Joe Huang 	
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
http://www.whiteboxtechnologies.com
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"building energy simulations at your fingertips"

On 11/3/2017 7:15 AM, Javed Iqbal via Bldg-sim wrote:
> In my past experiences, such problems were resolved by using detailed 
> spectral properties      (LBNL window output) in eQuest for an Indian 
> composite climate case.
>
>
> Sent from mobile, pls excuse typos
>
> On Nov 3, 2017 2:47 PM, "akshay gupta" <akshaykg at gmail.com 
> <mailto:akshaykg at gmail.com>> wrote:
>
>     Hi Javed
>
>     Thanks for helping. We were actually modelling using simplified
>     glass inputs. But I can try with detailed glass model as well.
>
>     Regards
>
>     On 3 November 2017 at 18:51, Javed Iqbal <javedvit at gmail.com
>     <mailto:javedvit at gmail.com>> wrote:
>
>         Thank you, Mr. Jim.
>
>         Apart from internal loads, it's worth looking into window
>         spectral properties. Sometime simple inputs like U value, SHGC
>         and Tvis is not enough and recommended to use whole assembly
>         window properties generated through LBNL window software which
>         could be imported directly into the eQuest.
>
>         It might help!!
>
>         Regards,
>
>         Sent from mobile, pls excuse typos
>
>         On Nov 3, 2017 1:37 PM, "akshay gupta via Bldg-sim"
>         <bldg-sim at lists.onebuilding.org
>         <mailto:bldg-sim at lists.onebuilding.org>> wrote:
>
>             Hi There
>
>             I am facing an issue in eQuest in almost all simulation
>             models for most hot and composite indian climates.
>             Whenever we reduce U-value of glass in model, from Single
>             Glazing U-Value of 1 Btu/hr Sqft F to 0.32 Btu/hr Sqft F
>             (or any other U-value lower than 1), we see an increase in
>             energy consumption.
>
>             Can someone point out principal mistake that may be making
>             in the model.
>
>             Thanks in advance.
>
>             Regards
>
>             Akshay Gupta
>
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