[esp-r] Re: G-value of the glazing system in ESP-r

[Achim Geissler]

Dear Hee

the g-value of a glazing is a "derived quantity" and is not explicitly entered in the construction (or anywhere in an ESP-r model). You enter solar absorption and transmission for each glass pane for a given glazing system for 5 angles of radiation incidence (the values for an IGU of interest can be generated by "3rd programs" such as LBNL Window or WIS). The (effective) heat gain through the glass is then calculated during run-time depending on the time step solar radiation incidence angle and surrounding air and surface temperatures. This will usually never be the same as the g-value you get from a glass supplier due to the fact that the supplier value is for perpendicular radiation on the glazing surface and also disregards air temperature differences either side of the glass.

Hope this helps.

Best
Achim


On Jan 9, 2011, at 1:19 PM, 한세희 wrote:

> Hi all
> 
> I have tried to get the G-value of the glazing system in ESP-r.
>  
> But I haven't been able to find it.
>  
> In fact, I found the 'view g-value' of the construction database and opened it. 
>  
> But, it showed  me different values such as emissivy, ref, o-ref, etc, not the g-value.
>  
> Could you tell me how I can find the g-value or calculate it based on those values mentioned above?  
>  
> Any prompt comment will be really appreciated.
> 
> Regards,
> 
> Hee
> -- 
> Han Sehee / Team Manager
> 
> Design and Simulation for Sustainability(DASS) Solutions Ltd.
> 4F WooAm Building, #355-22 Seogyo-dong, Mapo-gu, Seoul,
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> 
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> 
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achim.geissler at intergga.ch




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