The Namaqua chameleon’s ability to regulate temperature by changing its skin color inspired an energy-efficient coating that both cools and warms buildings.
A team of researchers from the Purdue University
(Indiana, U.S.A.) have recently formulated an energy-efficient and cost-effective coating that is able to keep the buildings cool in the summer and warm in the winter. The new solution has been created by mixing thermochromic microcapsules, specialised microparticles and binders to form a suspension, which is then sprayed onto a metal surface.
The newly-developed coating is inspired by the African chameleon Namaqua, who can alter its colour to regulate the body temperature as conditions change. The team led by Fuqiang Wang has therefore studied this phenomenon and created a colour-shifting coating that adapts as outside temperatures fluctuate.
When heated, the surface begins to change from dark to light grey. Once it reaches 86°F, the light-coloured film reflects up to 93% of solar radiation. In addition, the team has analysed the new solution in outdoor tests on miniature buildings throughout all four seasons with three conventional coatings – regular white paint, a passive radiative cooling paint and blue steel tiles – getting the following results:
- In winter, the new coating was slightly warmer than the passive radiative cooling system, though both maintained similar temperatures in warmer conditions.
- In summer, the new coating was significantly cooler than the white paint and steel tiles.
- During spring and fall, the new coating was the only system that could adapt to the widely fluctuating temperatures changes, switching from heating to cooling throughout the day.