Most high buildings have staircases. I wonder how we should calculate the lighting-levels to stay in accordance to 13201-regulations. I could calculate the lighting level on the ground, on table-height or even on a tilted surface. I think none of them would be correct. (I'm actually sure) One could of course calculate the lighting level for each step, which is nice to know and could be helpful but should we consider it to be the correct way to calculate stairs ? How do you, lighting colleagues, calculate staircases ? Looking forward to your feedback.