When cooking at home, be sure to match the size of the burner to the size of the pot you're cooking with. According to Recyclebank, a 6-inch pot on an 8-inch burner actually wastes 40 percent of the burner's heat. Simply moving the smaller pot to a smaller burner can help save energy and get the job done. And when reheating food, skip the oven and opt for smaller users of energy, like a countertop toaster oven or microwave. They have less space to heat up and can work just as well in a jiffy.