Daylighting in residential districts undergoing urban renewal

The quality and quantity of natural light entering a building depends on both internal and external factors. In Hong Kong, many buildings are high-rise blocks constructed close to each other and hence the external factor plays a significant role in daylighting designs. The situation is particularly acute in "old" districts, where existing low-rise buildings (usually 5-storey) are overshadowed by new high-rise (20-storey or more) apartment blocks. This study examines the effect of external obstruction on the indoor illuminance in existing low-rise buildings. The indoor daylighting levels for different floors were investigated in terms of daylight factors. It has been found that the daylight level of residential flats can be severely reduced due to neighbouring buildings. With severe external obstruction, the daylight factors for rooms on the ground floor can be as low as 0.1%.