Light Shelves in Sefaira


Can I use Sefaira to study the effects of Light Shelves?


The short answer is no!

The longer answer is that you can but the results will be difficult to distinguish between, in most cases, and the setup of the light shelf and other internal elements are mainly fixed and thus difficult to provide valuable feedback on the effects of the light shelf.

Material Assumptions

Sefaira daylight analysis is useful for typical rooms of offices, residential buildings and schools, using specific hours of the year, climate based modeling (sDA/ASE), average daylight factor (%ADF using CIE overcast sky) or direct sunlight (SEPP 65) but has fixed analyis inputs and so is limited in its further detail.

Analysis Assumptions



Here is an example of attempting to see the effects of a light shelf in Sefaira - 4m deep, glazed externally and internally, tagged as shading, wall and internal walls (all 0.4 reflectivity).

It is very hard to see any distinguishable daylight effects.








Here we delete the internal glazing element and the daylight factor does go up but the effect is still so small as to be indistinguishable. This may be the effect in reality but is also hard to control enough settings to derive value from the analysis.








It is possible to see changes in daylight results in Sefaira due to a light shelf but the sensitivity of the fixed analysis makes it very hard to interpret and make decisions based on the results.


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