New paint can heat and cool buildings reducing energy use

“For both heating and air conditioning we must reduce energy and emissions globally to meet our zero-emissions goals,” said Cui, who directs the Precourt Institute for Energy and the Sustainability Accelerator, both within the Stanford Doerr School of Sustainability. 

“How to reduce heat exchange between human living and work spaces and their surroundings is getting more attention, and new materials for enhanced insulation – like low-emissivity films for windows – are in demand.”

This is not the first paint to achieve cooling and heating but current options usually come with a metallic silver or gray color, limiting their applications. The newly invented paints come in a wide range of mat colors that can be applied to buildings in an aesthetically pleasing fashion.

The researchers tested their paints in eight colors: white, blue, red, yellow, green, orange, purple, and dark gray. The results indicated that they were 10 times better than conventional paints in the same colors at reflecting high mid-infrared light.

Better yet, the paints are not reserved for building and can be applied to a variety of objects to enhance both their cooling and heating attributes.

Various shapes and materials

“Both layers can be sprayed onto assorted surfaces of various shapes and materials providing an extra thermal barrier in many different situations,” said Yucan Peng, co-lead author of the study, who completed her PhD in materials science at Stanford in 2020 and is now a postdoctoral scholar in Stanford’s Geballe Laboratory for Advanced Materials.

The paints are also water-repellant making them ideal in humid environments. Furthermore, any surface coated with the paints can be cleaned easily with a wet cloth or water flushing.

More experiments also revealed that the paints’ performance and aesthetics were not altered after being exposed to one week of high temperature (176 degrees Fahrenheit), low temperature (-320.5 degrees Fahrenheit), as well as high acidic and low acidic environments. 

“Our team continues to work on refining the paint formulations for practical applications,” said the study’s other co-lead author, Jian-Cheng Lai, a postdoctoral scholar advised by Zhenan Bao, professor of chemical engineering.

 “For example, water-based solutions would be more environmentally friendly than the organic solvents we used. That could facilitate the commercialization of the paints.”