No one can deny that McDonald's food service is fast, but up until now it hasn't been very energy efficient.

The company's 32,000 stores spend a whopping $1.5 billion each year on cooking, lighting, heating and cooling.

With some help from Engenuity Systems, Inc., McDonald's expects to cut energy costs by 13.6 percent. Engenuity will install devices to turn off lights at certain times of day and when buildings are empty, as well as air conditioning and heating equipment that monitors temperatures and controls.

Each store location will also be able to set start and stop times for its equipment, so the sundae machines won't automatically turn on at breakfast.

McDonald's is currently testing Engenuity's equipment in Hong Kong and Korea, and expects to roll out the system worldwide later this year.