Re: [EnergyPlus_Support] solar transmittance

["Achim Geissler" <Achim.Geissler@xxxxxxxxxxxxxxxx>]

Hi,

no, the shading coefficient combines direct radiation and secondary
heat transfer (absorption and following convection). To complicate
matters, the SC refers the SHGC (solar heat gain coefficient) to that of
"a standard reference window of single-pane, double strength (whatever
that is) clear glass. SHGC_ref is approx. 0.8, so your SHGC is approx.
0.76 (0.95 x 0.8).

Achim


>>> bclwong@xxxxxxxxxxxx 08/17/04 01:05pm >>>
Achim,

Thanks a lot!
I've another question about "Shading Coefficient". The solar
transmittance 
of 0.775 of a clear glass I found form the datasets of window glass. It

indicates the shading coefficient of the clear glass is 0.95. As I know

that 0.95 means there will be 95% of solar radiation entering into the

space through the glazing, but why the solar transmittance of 0.775
is.

lee

At 12:51 PM 8/17/2004 +0200, you wrote:
>Hi,
>
>most probably your value is for normal incidence. In the simulation,
>solar radiation usually has an angle other than normal (smaller) for
>which transmittance is reduced (down to zero for parallel).
>
>Achim
>
>
> >>> bclwong@xxxxxxxxxxxx 08/17/04 12:49pm >>>
>Hi,
>
>I constructed a external wall with a window and without window
>shading device and window frame. The solar transmittance of the
>window glass is 0.775 (clear glass). But the simulated result of
>window system solar transmittance is 0.7. I wonder if someone can
>tell me why the difference was happened.
>
>lee
>
>
>
>
>
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