Cool coating technologies, also known as cool surfaces, can play a key role in making affordable housing more energy-efficient and sustainable, and buildings more habitable, says research institution South African National Energy Development Institute (Sanedi) energy efficiency cool surfaces project officer, Denise Lundall.

Cool roof coatings. Image credit: Finforum

Cool roof coatings. Image credit: Finforum

“Tests from the low-cost housing cool surfaces project in Groblershoop completed in April, in the Northern Cape, showed that the indoor daytime temperature of a low-cost, corrugated-iron house dropped from 34°C to 25°C.”

The design requirements for cool surfaces are onerous because they must reduce indoor temperatures, the cost of cooling and maintenance requirements, and must be inexpensive, fire retardant, waterproof and easy to apply.

Cool surfaces provide passive benefits by reducing heat entering structures and the energy required to keep buildings cool, which lowers the maximum energy demand. Applying cool coatings to low-cost housing and public buildings is a good starting point because it will support adoption at scale and help to meet these most pressing needs first.

“Cool coatings on public service buildings can dramatically lower the heating, ventilation and cooling costs, freeing up the maintenance budget, while providing more comfortable working conditions, says Lundall.

“Many of the public buildings we visited had inefficient or broken-down air conditioning equipment, and cool surfaces can reduce the indoor temperatures and improve the efficiency of air conditioning.”

The technology of cool surfaces, a branch of passive cooling technologies, is 30 years old, but still requires thorough assessment prior to local deployment, she highlights.

“We have been doing research on a range of projects for more than five years to determine the characteristics of cool coatings, such as formulations that are waterproof, elastic enough to accommodate often large local daily temperature ranges without peeling or cracking, are not damaged by constant, intense ultraviolet light, and can be used on concrete, tiles and corrugated roofing.”

Similarly, due consideration was given to the solvents, various additives and binders to ensure that they provide the desired additional benefits and do not contribute to pollution during application or during the coating’s life span.

Meanwhile, the 27 500m2 Groblershoop project and the USD100 000 grant the Sanedi cool surfaces projects received from the 1-Million Cool Roofs Challenge in October, have provided a welcome boost to momentum for the roll-out of large-scale demonstration projects and local use of cool surfaces, although the awareness of the technology among decision-makers is still limited, she avers.

“Using our research, decision-makers can now include cool surfaces as one of the technologies in their energy efficiency projects,” she says.

Lundall is working with insulation industry associations and serves on the South African National Bureau of Standards energy efficient buildings technical committee 204 SANS 10400 XA, with the aim of including the technology in the voluntary energy efficient buildings standards. A mandatory inclusion in the code will aid commercial and consumer adoption of the technology.

Source: Engineering News