Though it may not seem like the most glamorously green invention, this redesign of the common air conditioner could save a quadrillion BTUs a year in the United States alone.

• 虽然它看起来不像是最神奇的绿色发明，但是这种对普通空调再改造的设计确实可以帮助一年内减少上千亿单位的热量，而这仅仅只是在美国所估计的数量。