The company is testing the launch of a green store in Kissimmee, Florida, and will compare the profits and energy consumption to a regular store a few blocks away. It's already noticing much lower energy bills after switching to LED lighting, low-water plumbing fixtures, motion-detecting light sensors and passive cooling that uses wind rather than air conditioning.

However, Subway has made changes to all its stores as well, by switching to plastic cutlery made from polystyrene to cutlery and cups made of polypropylene, which is expected to save about 2,800 barrels of oil and 1,200 metric tons of carbon dioxide annually. And it recently decided to keep inventory closer to its stores, which has cut diesel consumption by about 1.6 million gallons annually.

Changes like this can make a huge difference with a company that now has 28,000 stores worldwide. McDonald's has about 30,000 restaurants – imagine how McDonald's could cut its emissions and waste if it made similar changes.