Cool Surfaces Project uses cool coating technology to mitigate climate change and protect South Africa’s fragile electricity grid.
The residents of Groblershoop in the Northern Cape had no choice but to sleep outside at night. With the temperatures in their corrugated iron homes soaring as high as 42°C in the evenings, it was too hot to remain indoors.
“It was bad during the day, too,” recalled Desmond Dube, the acting municipal manager of the !Kheis local municipality. “When you come home from work, you can’t go into the house immediately. You have to sit outside and wait for the house to cool off by opening the doors.”
Residents were using their homes as a “storage space”, said Denise Lundall, a project officer at the state-owned South African National Energy Development Institute (Sanedi), which is mandated to promote and advance energy efficiency. “That’s where they would lock up their possessions because they could not stay in that house … Imagine sleeping outside because inside your house is too hot.”
Pilot programme
Between 2015 and 2017, in a pilot programme, Sanedi’s Cool Surfaces project coated 27 500 square metres of roofing, spanning 425 homes, with cool roof coatings that incorporate high solar reflecting properties.
The benefits were immediate, with tests showing indoor daytime temperatures dropping from 34°C to 25°C.
“People were saying, ‘Oh my goodness, my baby can sleep in the house during the day’,” said Lundall, who runs the Cool Surfaces project. “One lady was so amazed that she could actually do ironing in the middle of the day because it was so much cooler.”
Cooling South Africa down
She said cool coatings are specialised paints that reflect heat and light away from the surface — a “paint-on solution” to cool buildings down. As a passive energy, it doesn’t use generated energy to keep buildings cool.
The project started in 2013 as a collaboration between the then-department of energy and the department of energy in the United States under the Clean Energy Ministerial, in response to South Africa’s need for a “low-carbon, low-cost, low-maintenance cooling technology for buildings”.
The initial focus was on roofing, but the project has since moved into coating walls, awnings and paving “because we’re finding out how absolutely useful it is”, Lundall said, adding that Sanedi wants to substantially improve the cooling effect nationally by tackling a pilot project to make road surfaces cooler.
Climate mitigation
The project works to alleviate the harmful effects of climate change by reducing greenhouse gas emissions and to help keep the global temperature from rising more than 1.5°C. For every 100 square metres of roofing that is “cool coated”, there is a reduction in the heating of 0.6 tonnes of greenhouse gas emissions annually for the lifetime of the roof.
Lundall said energy efficient cooling helps reduce the negative effect on South Africa’s “fragile” electrical grid by reducing consumption and demand for electrical cooling such as ventilation and air conditioning systems.
South African National Energy Development Institute
“The grid needs protection for the economy to run and for us to remain employed and alive … If our grid goes down South Africa will come to its knees,” she said.
The costs of electricity for cooling buildings are reduced, with Lundall citing how the municipal offices of !Kheis realised a 21% reduction in its electricity bill.
Thermal comfort is increased for people living in unelectrified buildings, which includes schools, warehouses and informal settlements, “thus improving health especially for the sick, the elderly and infants who struggle with heat exhaustion”.
Urban heat islands
According to a recent study, cities are warming 29% faster than rural areas, partly because of “urban heat islands”.
Solar energy reaches the Earth as heat and light, Lundall explained. “In cities, the buildings and roads absorb and accumulate that energy, holding onto it for long periods of time.”
South Africa’s cities are “superheated”, she said. “You actually see a shimmer over our cities — the urban heat island effect — and because of that, we’re trying to reduce the impact of solar heat from the sun on these urban spaces. If we can cool down the urban spaces, we give ourselves more time to find the solutions to our dependence on coal.”
Several factors affect how much heat a building gains. The darker the colour of the building, the more energy it will attract, while white or pastel colours make cool coatings more effective. The building materials of the roof or wall also play a key role.
“Some materials, like metals, allow for excessive heat gain and will gain heat even if painted white. While just painting surfaces white can assist in cooling, the addition of reflective substances like titanium dioxide substantially increases the albedo [reflect light and heat] making it a cool surface once coated.”
Cooling schools
At the Mgomoco Primary School in Sharpeville, Gauteng, classrooms have been cooled by between 8°C and 10°C through the project.
“Children are more alert, focused, and productive,” Lundall said.
The same benefits are being felt at Emmanuel Primary School in Sharpeville.
“The children can’t concentrate when it’s too hot as it gets especially after lunch,” said the school’s principal, Gloria Lebeoana. “We’re having a cool atmosphere now, which is more conducive to learning.”
Funding problems
Since 2015, Sanedi has “cool coated” about 200 000 square metres of roofs across South Africa and plans to complete a further 800 000 to one million square metres over the next three years. The bulk of these installations are being completed with the department of defence.
Lundall said the greater the surface area covered, the more effective the technology is at cooling. “Immediate relief can be obtained from extreme heat — three seconds after application.”
The project is funded through international grants, donations of materials and labour from manufacturers for charity events and the treasury. “While this project really should be rolled out nationally by the government as soon as possible, South Africa has strongly competing priorities for the fiscus, resulting in scant government financial support at the moment.
“Funding directly from the national government is a challenge to roll these out on a sufficiently large scale to affect a tipping scale of momentum to make implementation substantively impactful and sexy or fashionable”, Lundall said.
This means Sanedi must approach local municipalities individually, which delays low-income people benefiting from the project.
She said political unrest, social dissatisfaction and service delivery protests often prevent their work from keeping schedule. “An enormous amount of time and other resources must be spent on getting buy-in from the community beneficiaries.”
Sanedi’s employees do free energy efficiency awareness training, showing people “how to do more with much less electricity” and provide free professional, certified training and assessment on cool coating applications to residents of the project site. Graduates are then hired, under supervision, receiving skills development and jobs with valid experience.
Future plans include the addition of a fire retardant additive that will reduce the risk of property damage and loss of life from fires in informal settlements. “The earlier rollout of a fire-retardant cool reflective coating could have prevented the 122 houses in Masiphumelele being destroyed at the weekend,” Lundall said.
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