Struggling to decide on the most energy-efficient colour for his home, designer Joe Doucet created a climate-adaptive paint that shifts from white in the summer to black in the winter, changing at 25 degrees Celsius.
Inspired by childhood mood rings, Doucet recalled their color-changing ability, which he later learned was due to a thermochromic response—liquid crystal chains reacting to temperature changes. “I recall a fascination I had with a mood ring I received as a child and really trying to dig in and understand what it was,” he told CNN. “I knew, even as a 7-year-old, that (the ring’s changing colour) had nothing to do with my mood, that there was some type of chemistry at play.”
To create the paint, Doucet used thermochromic pigments made from these crystals, mixing them with standard house paint and additives. The result is a paint that shifts color when it absorbs ultraviolet light and reaches a specific temperature. He tested the concept using 3D-printed small models of his house, designed to match its insulation levels, and painted them in different colors. Within a year, he found that in winter, black models were about 4 degrees Celsius warmer inside than white ones, while in summer, white models were around 6.7 degrees cooler.
This aligns with common knowledge: light-colored buildings, like the white homes of the Mediterranean, reflect heat and stay cooler, while dark ones, like black houses in cold Scandinavia, absorb warmth. Doucet’s innovative paint leverages this principle to optimize energy efficiency year-round.
Despite the promising results of his early tests, which he described as a “great success,” Joe Doucet discovered that his thermochromic paint degraded under sunlight. After another year of experimentation, he resolved this issue by incorporating a protective additive. His climate-responsive paint, as he calls it, appears “very, very dark gray” below 25 degrees Celsius and gradually lightens as the temperature increases. Doucet has since applied for a patent for this technology.
With 2024 being the hottest year on record, surpassing 1.5°C above pre-industrial levels, the need for such solutions is clear. The paint could cut household energy costs by 15–30%, significant given that 88% of U.S. homes use air conditioning and buildings account for 30% of global energy use.
Applicable to homes, schools, and factories, it offers broad potential, though Doucet notes it’s less effective in consistently hot or cold climates. Nevertheless, Doucet sees his creation has a potentially huge market. Not only could the paint be used on homes, but also larger buildings like schools, factories and other structures requiring a controlled internal environment.
“There is no single solution to climate change. It’s a series of steps and small actions,” he remained cautious. “But this could be a meaningful one.”
