It took a decade to perfect, but the newly-developed “liquid window” can block out sunlight to keep a building cool, while also being able to absorb heat that can be released to cut heating costs.
The invention by researchers at Nanyang Technological University, Singapore (NTU) uses a gel liquid between glass panels, which can reduce energy consumption by up to 45 percent compared with normal windows.
This is good news, since buildings account for about 40 percent of global energy usage to keep them cool or warm, according to a UN report.
Reuters quoted one of the scientists as saying the new product could be used in both small and large applications.
"Previously people only talked about blocking the sunlight in the summer and letting the sunlight come in in the winter, but nobody talked about heat storage - we're the first to do this," said lead researcher Long Yi.
The liquid mixture in the "smart window" turns opaque or frosted in appearance when exposed to heat, blocking sunlight.
When temperatures cool, it returns to its original clear, transparent state, letting in light and heat.
The product works best in areas where it is extremely hot during the day, but where temperatures plummet at night.
The researchers hope to attract commercial interest in the “smart window”.