Sefaira - NEN 2057 daylight norm


I’m currently using the Sefaira plugin in Sketchup to do some daylight simulations. I would like to calculate the equivalent daylight surface area (DUTCH: equivalent daglichtoppervlakte) according the norm NEN 2057 as Sefaira states that they cope with this Dutch norm.

However, I have not found a way to do this.

Anyone else that tries this or that has a solution for this?

Thanks in advance!


Hi Stefan,

Thanks for your question.

I’m not familiar with the standard - are you able to summarise what it actually measures in a bit more detail please? How does it measure natural light and where?




It measures the surface area of the windows that receive direct sunlight independent from time and date. It uses specific rules to define which part of the window can be included and which part not; depending on shading objects such as an overhang above the window and balcony fences etc.

It’s very specific, so I cannot describe the entire norm/standard, but this is a general explanation.


Thanks Stefan.

So based on your description, the short answer is no, we don’t currently include a way to help with that kind of calculation.

However we’re very interested in understanding more about other standards people want to use for studying daylight. It also sounds like the sort of thing that would not be difficult to calculate automatically within our engine. I’ll be in touch separately to find out more about how you are using it and how it works.





It is the standard we use in The Netherlands nowadays, so I can imagine that more people would be interested in it.