Color-Changing Roof Tiles: Dark In Winter & Light In Summer

If you have ever been in an attic in the summer, you know it can be incredibly overheated. In the winter, on a sunny day, it can be surpisingly warm. A group of students are working on a way to have the best of both worlds.

Physorg.com reports:

"The ideal situation, then, would be to get the advantage of white roofs when it's hot and black roofs when it's cold. Now, there may be a way to have both. A team of recent MIT graduates has developed roof tiles that change color based on the temperature. The tiles become white when it's hot, allowing them to reflect away most of the sun's heat. When it's cold they turn black and absorb heat just when it's needed.

The team's lab measurements show that in their white state, the tiles reflect about 80 percent of the sunlight falling on them, while when black they reflect only about 30 percent. That means in their white state, they could save as much as 20 percent of present cooling costs, according to recent studies. Savings from the black state in winter have yet to be quantified." See full article.

Roofs That Generate Electricity

Roof tops are a huge potential source of power and using solar roof "shingles" show great promise. Photo by Pam Owen RLEP.org

The Energy Harvesting Journal Reports:

"A transparent thin film barrier used to protect flat panel TVs from moisture could become the basis for flexible solar panels that would be installed on roofs like shingles. The flexible rooftop solar panels - called building-integrated photovoltaics, or BIPVs - could replace today's boxy solar panels that are made with rigid glass or silicon and mounted on thick metal frames. The flexible solar shingles would be less expensive to install than current panels and made to last 25 years.

'There's a lot of wasted space on rooftops that could actually be used to generate power,' said Mark Gross, a senior scientist at the Department of Energy's Pacific Northwest National Laboratory. 'Flexible solar panels could easily become integrated into the architecture of commercial buildings and homes. Solar panels have had limited success because they've been difficult and expensive to install."' See full article.