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

[Aizaz Samuel]

Reporting the g-value is a necessary requirement for compliance with 
CIBSE TM33:2006 (and later). ESP-r just reports the g-value and does not 
perform any calculations based on it like Achim mentioned. You can 
report g-values using ESP-r for user defined fenestration systems (there 
is some help available in the interface) by choosing view g-value > 
choose a construction type > user defined.

Calculation of g-value is derived from BS EN 410:1998

-Aizaz


On 01/10/2011 08:04 PM, Achim Geissler wrote:
> 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,
>> Rep. of Korea (Post Code: 121-838)
>>
>> T: +82 2 913 2585
>> F: +82 2 949 2585
>> M: +82 10 5095 8155
>>
>> www.dasskorea.com <http://www.dasskorea.com/>
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>
> achim.geissler at intergga.ch <mailto:achim.geissler at intergga.ch>
>
>
>
>


-- 
Dr Aizaz A Samuel
Department of Mechanical Engineering
University of Strathclyde
James Weir Building
Glasgow, UK

t: +44 141 548 5765
f: +44 141 552 5105
e: samuel at esru.strath.ac.uk

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