Breeam daylight requirement - Dirt factor

I am calculating daylight for a Breeam project and I came across a compliance note regarding a dirt factor. It states:


Dirt factors when calculating daylight - Daylight calculations should include a maintenance factor for dirt on the windows. An example is given in British Standard Code of Practice for daylighting, BS 8206 Part 2, appendix A1.3."

Does anyone here have any experience with accounting for a dirt factor? Is it perhaps included in the daylight factor component in Honeybee?

Thanks in advance!

I suggest you to follow this web site:



@mostapha Iā€™m wondering if could be an idea to develop an tool to set the glazing according to BS 8206 Part 2 and it could be useful for the other radiance user to take into account the external environmental conditions as well as the maintenance factor.


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I agree! This can be implemented under Glass material in [+] and as a component in the legacy library.


My apologies for a long overdue reply. Thank you for the link! I was not aware of this tool :slight_smile: