Some govt buildings, houses are getting ‘cool roofs’ – which can cut indoor heat by more than 25%
The technology is very simple: Roofs are painted with special thick white, durable coatings that reflect sunlight.
“It is an inexpensive and highly effective passive energy, low-tech cooling intervention,” says Denise Lundall, project officer of energy efficiency at the South African National Energy Development Institute (SANEDI), a government agency.
Last year, SANEDI won a R1.7 million grant from the Million Cool Roofs Challenge to assist in covering roofs in South Africa. The challenge is a global initiative to reduce air conditioning, which is already consuming almost 13% of international electricity demand – and air conditioning power use is growing by almost 3.5% a year, according the International Energy Agency.
One of SANEDI’s first cool roof projects was a low-cost housing project in Groblershoop in the Northern Cape province. The roofs were painted with reflective coatings, which reduced the daytime indoor temperatures from above 34°C to 25°C – a reduction of almost 27%.
“In high-rise buildings such as those in Sandton, cool roofing has the potential to decrease top-floor air-conditioning energy use by as much as 20%,” says Lundall.
SANEDI has added cool roofs to three schools in Sharpeville, Gauteng, and has started to cover 9,500m2 of roofing at the Makhado municipality buildings in Limpopo.
Elsewhere in Limpopo, working in collaboration with the Department of Defence, 15 000 m2 of roofing will be coated at a military site. SANEDI is also exploring the application of “cool paving” at the site.
In the Western Cape, SANEDI will be coating a total of 26 000m2 of roofing on low-cost houses. “Of these, the temporary housing settlement of Masonwabe will be both cool coated, as well as insulated. This forms part of a proof-of-concept project to investigate the interaction and mutual benefits that cool roofs and insulation can achieve, when combined,” says Lundall.
SANEDI was supposed to spend the R1.7 million on cool roofing by December this year, but Lundall says the Covid-19 pandemic "resulted in unfortunate and unavoidable delays in our implementation plans". It has now been granted an extension, and a further R400,000 to get it "back on track".
"Heading into what is sure to be a scorching summer, we are excited to resume projects across the country,” says Lundall.