In case of deeper interest in daylight qualities, climate-based daylight performance metrics can be used. Climate based daylight simulations enable to consider further design factors as seasons, time of day, façade (window) orientation, location (latitude) of the building, climate circumstances, direct solar ingress, shading and glare prevention, variable sky conditions, building type and occupant requirements.

The calculation preconditions for the climate based daylight-modelling relies on the method described in EN17037 - Daylight in Buildings, Daylight provision calculation method 2. For a space with vertical and/or inclined opening with a given target illuminance of 300 lx, at least 25% of the yearly hours, the results shall be above the target value. The minimum illumination limit is 300 lx in residential buildings. In case office or other public buildings are evaluated, the limit is 500 lx.

Total average DA = total weighted score/total hours use

The total average DA is based on multiplying the DA300/50 dwelling (DA500/50 offices) for each room with the amount of hours spent and the number of people in that room during daylight hours, then dividing by the total number of people-hours (see also table 1 on page 10). In case no actual or predicted use numbers are available, use the default use hours in the table below.

This way, the rooms that are being used while there is daylight, such as the living room, will contribute with higher weight than, for example, the master bedroom, which is used by adults mostly during the night.