Illuminance simulations should be perform for all the regularly occupied spaces. What if I have 20-storeys building with same geometry and same layout? Simulating each floor seems pointless, becasue results would be almost the same. External obstructions do not influence the building, so the sunlight conditions would be the same (only floor height will change). What I want to do, is perform simulations for two floors: the highest and the lowest and then extrapolate the results for the other floors. Is this approach correct?