SA Affordable Housing January / February 2017 // Issue: 62 - Page 15

COVER STORY University of Pretoria releases energy usage study of walling in South Africa The University of Pretoria has released results of its Thermal Performance Study, which assessed operational energy use of structures built with six different walling materials. Photography courtesy of Berts Bricks. W hen selecting building materials, developers and architects of green buildings take into account the embodied energy of their raw materials. While this is an excellent start, in reality energy use over the life of the building dwarfs energy used during production. Operational energy use is an expensive, long-term cost for the property owner and a drain on South Africa’s limited resources. Annual Operational Energy is the sum of all heating, cooling and ventilation electricity costs accumulated over all four seasons in one year. This research is of particular relevance for affordable housing, as the residents do not have the money for high electricity bills. Therefore ethical housing developers should look beyond cost-cutting during construction, to take into account the long term expense of operation and maintenance. METHODOLOGY OF THE STUDY The size and use of a building influences its thermal performance. The design models applied in this study were used in prior research by the Council for Scientific and Industrial Research (CSIR) and the Department of Mineral and Energy Affairs. Best-practice construction methods were assumed, as required by SANS 10400 Part XA: Energy usage in Building and SANS204: Energy efficiency in building. Three building types were analysed: • A large 2 000m2 commercial building that is unoccupied at night and on weekends. • A middle-income residential home of 130m2. • A low-income home of 40m2 (with heating fuelled by coal or paraffin). Variables such as floor, roof, windows, doors and occupancy patterns were kept constant. AFFORDABLE SA HOUSING JANUARY - FEBRUARY 2017 13