Cooking in the average U.S. home uses enough energy to generate 1/2 ton of greenhouse gases a year. Every gallon of water boiled produces one pound of emissions. There is no standard energy rating for cooking appliances, but bear in mind that a conventional oven will produce double the emissions of a gas or microwave oven and bigger appliances are less efficient than smaller ones. Use a microwave or toaster oven whenever possible. Also, when buying new appliances, choose one with the Energy Star label for reduced energy consumption and electricity bills.
With the help of Energy Star, Americans saved enough energy in 2006 alone to avoid greenhouse gas emissions equivalent to those from 25 million cars- all while saving $14 billion on their utility bills.