The latest from MIT students is a concept for color-changing roof tiles that suck up heat in winter and reflect it in summer. The prototype tile will turn dark in winter and white in the summer. While white roofs are said to be a great option to eliminate greenhouse gas emissions, some people believe that the gain in summer could be overshadowed by the loss in winter. The best thing here would be white roofs in warm weather and black roofs in cold weather. The tiles developed by the team of MIT students, also called Thermeleon, are able to change color based on the temperature. They turn white during warm weather to reflect away most of the sun’s heat, and in cold conditions, they turn black to absorb most of the heat. The Thermeleon team grabbed first place in this year’s Making and Designing Materials Engineering Contest.
When white, these tiles can reflect about 80 percent of the sunlight, while it’s just 30 percent when black. So, in the white state, these tiles are being claimed to save as much as 20 percent of current cooling costs. On the other hand, the savings from the black state are yet to be calculated. For the development of such tiles, they used a common commercial polymer in a water solution. This solution is encapsulated between layers of glass and plastic in their original prototype, and between flexible plastic layers in their latest version, with a dark layer at the back. During the low temperatures, the polymer stays dissolved and makes way for the black backing. When the temperature rises, the polymer squeezes to form tiny droplets, whose small sizes disperse light, creating a white surface.
Since the materials needed to make these tiles are easily available and inexpensive, the team hopes that the tiles can be manufactured at a very reasonable price. Durability is one area where these tiles have to be tested, and that could be done only after the material is passed through repeated hot-cold cycles.
Via: MIT News
