[Bldg-sim] EnergyPlus - Surface Outside Face Sunlit Fraction for Shading Devices

Michael J Witte mjwitte at gard.com
Thu Oct 4 12:10:15 PDT 2018


Correct. Sunlit area applies to direct (beam) solar and is the result of 
the surface (building and shading) shading calculations.

Shading devices (blinds, shades, and screens) are modeled as part of the 
window system, because there can be more interactions than just 
impacting sunlit area. There can be inter-reflections between the 
glazing and the shading device, beam can be changed to diffuse, etc. 
There are many output variables that report various details of the 
window system and shading device. Search the RDD output for "Surface 
Window".

Mike


On 10/3/2018 10:12 AM, Spyros Akritidis via Bldg-sim wrote:
>
> Hello everyone!
>
> I am using EnergyPlus in order to calculate the sunlit fraction (by 
> unreflected beam solar radiation, as specified in the Input-Output 
> Reference) of window glazing areas with the presence of external 
> shading devices (e.g. venetian blinds, shades). The output values of 
> Surface Outside Face Sunlit Fraction seem to be unaffected by the 
> presence of these shading devices.
>
> I also tried another case: I removed the shading devices and added an 
> overhang (through the Shading:Building:Detailed object in EnergyPlus). 
> This time I get variable output values of Surface Outside Face Sunlit 
> Fraction, indicating that the overhang was taken into account.
>
> So, is it safe to suppose that, at the moment (at least), EnergyPlus 
> cannot calculate the sunlit area of external surfaces that are shaded 
> by shading devices like blinds, shades, screens etc.(I guess it has to 
> do with the polygon clipping algorithms) ?
>
> Or is there a way that can be calculated in EnergyPlus?
>
> Thanks,
>
> Spyros
>
> Spyros Akritidis
>
> Research Student
>
> School of Architecture, Building and Civil Engineering
>
> Loughborough University
>
> m: +44 077 6399 5008
>
> e: S.Akritidis at lboro.ac.uk <mailto:S.Akritidis at lboro.ac.uk>
>
> Linkedin-logo 2 <https://uk.linkedin.com/in/spyrosakritidis>photo 
> <https://www.researchgate.net/profile/Spyros_Akritidis>
>
>
>
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