From the New York Times. Lots of math to dig out here:
http://opinionator.blogs.nytimes.com/2015/02/06/investing-in-energy-efficiency-pays-off
The idea that money is available for the taking defies economic logic. But sometimes it’s true. That’s the case with a vast opportunity that’s routinely overlooked by institutions across the country — from universities to hospitals, companies to governments. The opportunity is investing in energy efficiency.
Retrofitting buildings for energy conservation in the United States could save $1 trillion over a decade, reduce American greenhouse gas emissions by 10 percent, and spur employment across the country.