ATTENTION painting and decorating contractors.
Fancy offering clients the opportunity to change the colour of their homes four times a year without having to go through the hassle of repainting it over and over again?
Soothing cool blue tones during the hot summer evenings could give way to vibrant reds during the long winter nights thanks to a heat-sensitive paint developed by boffins at Tongji University in China.
Yiping Ma and his research colleagues approached the idea of colour-changing paint pigments by searching out 'thermochromic' materials, substances that alter their shade under the influence of heat, capable of being mixed into domestic paint.
At first the team found that most of the pigments changed colour at too high a temperature to be useful. But they discovered a substance called crystal violet lactone, which produces a variety of hues at close to room temperature.
But in order to prevent the crystal violet lactone from reacting with chemicals in the paint, Mr Ma and his team encapsulated the pigment in a transparent polymer before stirring it into standard domestic wall paint.
When applied it has the notable side effect of increasing the internal room temperature during the winter months and decreasing it during the summer, helping to improve energy efficiency.
'The coating can decrease the temperature by about 8 deg C in summer and increase it by about 4 deg in winter, ' he said.
Estimates put the longevity of the paint at four years but Mr Ma is hoping to extend this to help provide a thermally comfortable environment without consuming fossil fuel.