3 Recommendations for electric lighting with daylighting

If electric lighting is not normally to be used during daytime hours, the average daylight factor should be not less than 5 per cent. The internal reflectances and the positions of windows should be such that inter-reflected lighting in the space is strong and even. When the shape of the room causes the distribution of daylight to be very uneven (such as when a large area lies behind the no-sky line – see section 3.1.1, Initial appraisal of daylight quantity), supplementary electric lighting may still be necessary.