I would like to know the basic formula for designing a indoor and outdoor lights. Let's suppose i am going to light a room with an area of 50m2(10*5), so the formula what i know is Illumination = Area*Lumen/Watts*Total Wattage*Light depreciation factor*Maintenance factor. But how to add height into it i mean what's the exact method or formula when considering height as well!! confused :/ Please help!!