Defeating the heat with a simple retrofit

Heat is one of the most significant challenges for Australia, and retrofitting buildings and transport to reduce the impact is crucial. Turns out, with the help of a little bit of rocket science, some chemistry and a spray gun, it’s possible to achieve thermal protection at scale.

The City of Adelaide has just released a University of Adelaide research report on a cool roof option that is achievable at scale around the country. The project examined the impacts of applying Super Therm coatings to two buildings that experienced major heat gain on sunny days.

The coating comprises ceramic compounds, acrylic and urethanes that can be applied with either brush or spray.

It reduces heat entering a building by a combination of reflectance and managing emissivity – in other words, it blocks over 95 per cent of visible light heat, UV heat and infrared heat, and it also does not absorb the heat and then transfer it to other materials or spaces.

Motivations for the research

The pilot project was part of the council’s development of the climate-ready Adelaide plan within the Integrated Climate Strategy 2030 adopted by the council in 2024.

The research also addresses a knowledge gap. Australia currently has no national standard for the design or performance of cool roofs, which means there are no benchmarks to determine whether a type of roof is or is not in fact a cool one.

On a technical level, the project aimed to gather temperature data for a coating that combined high reflectance (albedo), low thermal connectivity and high emissivity.

This ticks off the major sources of heat in a building – reducing direct absorption of heat from the sun, transfer of heat (thermal bridging) and radiation of stored heat by materials (emissivity).

Coatings are also relatively easy to apply, requiring no structural reinforcement or significant capital work.

The researchers also tested the theory posed by some researchers from Standford that cool roofs can increase surrounding ambient temperatures above the building, due to the reflected heat. Their temperature readings found no such increase occurred.

What they found:

• reductions in the surface temperature of the roof
• reduction in surface temperature 20 centimetres above the roof
• reduction in ambient temperature in the roof cavity
• the coating could maintain indoor air temperatures up to six degrees lower than outdoor temperatures during heatwaves

NASA was helpful

Super Therm is manufactured by US-based SPI Coatings and distributed in Australia by NEOTech Coatings.

Managing director of NEOTech Coatings, Shane Strudwick, tells The Fifth Estate that SPI founder, Joseph Pritchett developed the product through a process of experimentation.

He requested details from NASA of the ceramics used in spacecraft tiles and tested them, with four of those compounds being incorporated into the final formulation, along with acrylics and polyurethane.

It has been tested by the US Department of Energy for performance and by the USDA for non-toxicity.

Case studies

Strudwick says it has many applications beyond roofs. For example, it was painted on a sun-exposed brick wall of a data centre in Adelaide that had an issue with solar gain triggering the internal heat alarms in the data halls. The coating rectified this.

It has also been used to coat refrigerated transport, which delivers a major fuel saving by reducing the amount of time the engine needs to be idling to keep the cooling system working and counteract heat gain while a vehicle is parked.

A home in Sydney built of Modwood – a dark plastic material – was unbearably hot. Now it isn’t, and a home out in the Flinders Ranges has gone from needing air conditioning operating nine hours a day to just one hour a day.

It’s also been deployed on water tanks, pipelines and balustrades.

Physics in action

The combination of heat reflectance and extremely low transference and emissivity is the important thing, Strudwick says.  

“Heat is like water, it flows,” Strudwick says.

On a roof with solar panels for example, while the panels will convert heat to energy, the flashing will absorb it and transfer it down into the roof space. Heat in a roof space means impacts for ductwork, electrical cabling and other materials.

Where a home has a steel frame, heat entering from either roof or walls can transfer to the steel of the frame and flow right through the house. He explains he’s tested this himself using infrared photography to compare a standard steel frame and a coated steel frame

“A lot of people don’t realise, and they wonder why their home is so hot, even with insulation in the roof and walls.”

Another aspect of the product is its ceramic composition means it reduces the transfer of electromagnetic frequencies beyond the EMF of radiant heat. Sound, for example, is an EMF, and the company is currently undertaking testing of the product’s properties as acoustic insulation.

“We trade on testing, results and case studies,” Strudwick says.