Habitable rooms must have windows, where suited to the room's use, so that available natural light gives an average daylight factor of at least 2%. Artificial lighting giving at least 20 lux must be installed to allow occupants to move safely; this applies to sanitary compartments, bathrooms, shower rooms, airlocks, laundries and similar spaces where suitable natural light is not available. Verification Method H4V2 calculates the average daylight factor of each window from its net glazed area, the room's total internal surface area, the glass's diffuse transmittance, the visible sky angle and the area-weighted average reflectance. Deemed-to-Satisfy route: H4D6, light to Housing Provisions Part 10.5 (window area as a proportion of floor area, borrowed light, roof lights and artificial lighting).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.