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Energy saving with cool-roof thinking

by Ofentse Sefolo
Energy saving with cool-roof thinking

South Africa’s erratic power supply due to poor energy infrastructure development and maintenance has resulted in frustration and despair for the majority of South Africans. It has also been several years since the signing of the famous Paris Climate Change Agreement, yet we are still no closer to a more energy-efficient world.

Denise Lundall, project officer for energy-efficiency cool surfaces at the South African National Energy Development Institute (SANEDI), says while South Africa is essentially a hot country, it is easy to forget this in our winter months, when much electricity is used for heating. It is safe to say that just as much of our urban energy use is spent on cooling down buildings.

We are also facing hotter and drier summers and continued high levels of greenhouse gas emissions in comparison with our African neighbours.

“The way we cool our living and working spaces should go beyond comfort. We need to focus the attention on demand-side management actions and decrease our reliance on electrical appliances to keep us cool,” she explains.

Sustainable energy practices are vital
Passive energy cooling technology is at the heart of achieving more sustainable energy practices when it comes to lowering the temperature

Non-air-conditioned buildings and cities are increasingly becoming too hot for acceptable habitation, with air-conditioning consumption reaching 12,7% of the projected global electricity demand.

According to the International Energy Agency, electricity-to-power cooling in buildings is the fastest growing end-use sector at almost 3,5% annual growth globally.

“We need a smart solution to this demand, to play our part in keeping the global temperature from rising 1,5°C, before it becomes irrevocably unsustainable. The answer lies in cool surfaces technology,” she notes.

According to the International Energy Agency, electricity-to-power cooling in buildings is the fastest growing end-use sector at almost 3,5% annual growth globally.

Roofs offer a cool solution
Roofs are one of the targeted surfaces we aim to passively address through cooling. Cool roofs simply involve the coating of roofs with a durable, reflective membrane, which reflects the heat of the sun. It is an inexpensive and highly effective passive-energy, low-tech cooling intervention.

Cool roofs allow less heat into the building, making non-air-conditioned homes, warehouses and other buildings much cooler.

Lundall explains: “In high-rise buildings such as those in Sandton, cool roofing has the potential to decrease top-floor AC energy use by as much as 20%. Combining this with proper ventilation, provides urban areas with a low-energy cooling solution and a substantially decreased carbon footprint.

“Cool roofing also holds the potential to decrease ambient outdoor temperatures. Used comprehensively throughout an area, the solution can create a ‘cool bubble’ up to 4°C cooler than without a cool membrane on the substrate.”

Cool roofs simply involve the coating of roofs with a durable, reflective membrane, which reflects the heat of the sun. It is an inexpensive and highly effective passive-energy, low-tech cooling intervention.

Achieving sustainability
Every entity and department play a role in our country’s energy-efficiency landscape. At SANEDI role players are constantly engaging with key stakeholders, including industry bodies and local governments, to achieve a wider rollout of cool roofs in the country. The aim is to develop innovative, integrated solutions to catapult growth and prosperity in the green economy.

“If rolled out throughout a country, you can just imagine the vast aggregated benefits to be reaped from this low-tech solution. However, to make a sizable difference, we need the continued support of government,” concludes Lundall.

For more details about cool roofs, visit www.sanedi.org.

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