Daylighting: A Residential Energy-efficiency Demand-side Management Initiative

The persistent energy crisis faced in South Africa due to ageing power plants and increasing energy demand has made energy an issue of availability rather than affordability. Utilising natural energy sources for daily needs, have been proven to minimise energy consumption and ensure energy availability. This study explores the potential energy savings and resultant economic benefit as well as environmental sustainability due to daylighting in a house. Solar global horizontal irradiance and indoor illuminance of the passive solar house was monitored using a Li-Cor photometric sensor and Kipp & Zoncn pyranometer, respectively; covering clear and overcast sky days. Between 071100 to 16h30, the average indoor daylighting was 217 lux on a clear sky day and 114 lux on a cloudy sky day. The obtained clear sky indoor daylighting is sufficient for domestic visual activities, but electric lighting is required indoors on an overcast sky day to achieve visual comfort. Daylighting implementation indoors resulted in a daily cumulative energy savings of 0.24 kWh. Also, 47% monetary savings and reduction of all environmental elements emitted or used in a coal-fired power plant were achieved. Integration and active practice of daylighting in the South African residential sector can reduce the overall energy demand in the domestic sector and promote energy security without compromising service level or occupants' visual comfort.