Re: AW: [EnergyPlus_Support] radiation terms

[Frederick Winkelmann <FCWinkelmann@xxxxxxx>]

For calculating IR from the ground, the ground is assumed to have an IR emissivity of 0.9 and a surface temperature equal to
the outside air temperature. The ground temperatures from the weather file are not used.

The IR from the sky depends on the sky temperature, which is calculated from outside air temperature, atmospheric moisture
and cloud cover.

Fred Winkelmann

Alexander Beisteiner wrote:

> What about the IR heat exchange? The IR heat exchange with the sky can
> be estimated from the known sky and surface temperature. In the case of
> the IR heat exchange with the ground, do the ground temperatures from
> the weather file have to be accounted for? What is the IR emittance
> coefficient for the ground like in EPlus?
>
> Thanks
> Alexander
>
> -----Ursprüngliche Nachricht-----
> Von: Frederick Winkelmann [mailto:FCWinkelmann@xxxxxxx]
> Gesendet: Donnerstag, 19. Juni 2003 22:07
> An: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Betreff: Re: [EnergyPlus_Support] radiation terms
>
> The resported sky diffuse, ground diffuse and beam radiation incident on
> a surface are all solar quantities. They should be
> multiplied by the solar absorptance of the surface to get the amount of
> each that is absorbed.
>
> Fred Winkelmann
>
> idoebber wrote:
>
> > I am trying to calculate the total radiation incident on a surface
> that is
> > absorbed.  The outputs for radiation incident on a surface are sky
> diffuse,
> > ground diffuse, and solar beam.  Yet the absorptance constants for the
> > building material are thermal, solar, and visible.  How do I calculate
> the
> > fraction of each radiation that is absorbed.
> >
> > Thanks
> > Ian
> >
> >
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