See-through film rejects 70 percent of incoming solar heat
To battle the summer heat, office and residential buildings tend to crank up the air conditioning, sending energy bills soaring. Indeed, it’s estimated that air conditioners use about 6 percent of all the electricity produced in the United States, at an annual cost of $29 billion dollars — an expense that’s sure to grow as the global thermostat climbs. Now MIT engineers have developed a heat-rejecting film that could be applied to a building’s windows to reflect up to 70 percent of the sun’s incoming heat. The film is able to remain highly transparent below 32 degrees Celsius, or 89 degrees Fahrenheit. Above this temperature, the researchers say, the film acts as an “autonomous system” to reject heat. They estimate that if every exterior-facing window in a building were covered in this film, the building's air conditioning and energy costs could drop by 10 percent. The film is similar to transparent plastic...