In terms of energy use, windows are often a weak link in buildings. What if, instead of being the source of energy loss, they were a source of power?

New Energy Technologies Inc. has been working with the U.S. Department of Energy's National Renewable Energy Laboratory on a transparent coating that incorporates "the world’s smallest functional organic solar cells." The company is working on several applications for window glass, as well as a film that can be applied to existing windows.

Aside from providing a source of renewable energy with ultra-thin technology, New Energy Technologies' solution makes use of existing infrastructure. What other solutions have you seen that increase resource performance through more than one avenue?