Wal-Mart stores opening in Canada next year will be designed to save 30 percent in energy use, said the head of the discount behemoth's Canadian unit.

"We call them Wal-Mart HE -- a high-efficiency prototype," David Cheesewright, ceo, Wal-Mart Canada, said in a speech to a meeting of Ontario cities. Cheesewright told Reuters that the new, greener stores would result in a savings of $24 million U.S. (or $25 million Canadian) over five years, as compared to energy costs at traditional outlets in 2005.

The energy savings will accrue from using waste energy from refrigerators to help heat stores, cutting lighting costs, covering roofs with white membranes to reflect the sunlight and lower summer cooling costs, and by reducing the size of store buildings.

Cheesewright said Wal-Mart would continue to pursue three long-term sustainability goals around the world: producing zero waste, operating with 100 percent renewable energy, and making environmentally preferable products available.