Axalta’s new POLAR coatings reduce surface temperatures of buildings by up to 20ºc. We spoke to EMEA specifications manager Mercè Berengueras to find out how.

Cool buildings

For centuries the wisdom on keeping building facades cool has centred around the use of pale colours. But a new product from Axalta is changing all that. POLAR is a range of powder coatings for metal substrates with trademarked ‘Cool’ properties, part of the Alesta SuperDurable range. Launched in 2019, POLAR now offers a palette of six darker-hued coatings with a formulation specifically designed to reduce heat gain.

“In a way you can think of POLAR as a bit like putting sunscreen on your face”, says Berengueras. “POLAR is formulated with special pigments that reduce infrared light from the sun. The infrared part of the radiation spectrum is what’s largely responsible for heating. POLAR protects against the absorption of that infrared light, and that’s what helps mitigate against heat.”

“It’s good news for design because a deeper-hued architectural expression is now perfectly possible without jeopardising a cooler façade – that’s why we say that dark buildings can now be as cool as white ones.”

The concept behind POLAR began as part of a quest to make outdoor furniture more comfortable, with Axalta researching a solution that meant you could sit without discomfort on a dark metal chair, for instance, even when it had been baking in the sun all day.

“But we were very aware from day one that it could be a transformative solution for buildings and cities too,” she adds. “A façade surface that absorbs less heat will of course transmit less heat into a building and that, in turn, reduces demand for mechanical cooling.” 

POLAR is also good news for the environment because a cooler façade will have less heat impact on the temperature of surrounding streets and surfaces – something that is becoming increasingly important in our cities as architecture adapts to the demands of climate change and the urban heat island effect.

Putting POLAR to the test

To really put the new technology to the test, Axalta took to the streets of Barcelona in high summer, constructing a pair of identical sculptural forms in steel. Resembling mini Seagram Buildings, one form was coated in POLAR, the other in a standard black coating.

“We called the exercise ‘Alesta Cool on Tour,’ says Berengueras, describing how the sculptures were installed side by side at sun-baked locations across the city, such as alongside Gaudí’s La Sagrada Familia and among the architectural icons of the Olympic Port, including Gehry’s fish sculpture. The temperatures of the respective forms were monitored by Axalta from early morning through the heat of the afternoon and into the evening.  

“The surface temperature of the POLAR-coated form proved up to 20ºc cooler than that of the structure with the standard coating,” remarks Berengueras.

Attention to detail

Another important application for POLAR is the aluminium or steel profiles that form part of many façade systems. “The façade systems of today employ increasingly slim components; part of a general tendency to lean buildings that use less materials,” says Berengueras. “But as designers know, heat gain can have a significant effect on very fine tolerances, particularly in relation to any moving mechanical element like the operation of a window.”

In response, POLAR coatings were developed in part to reduce the thermal stress that leads to the expansion – and subsequent contraction – that occurs when building components are subjected to extreme heat.

“It feels really positive to be part of a solution for architecture and environments of the future,” says Berengueras, “The team here is very proud of its work.”