Single and even double ovens are standard equipment in most homes today. They come in electric and gas models. Of the two, electric models are usually a little less expensive and installing them does not require connection of a gas line. Ovens with a self-cleaning feature are usually a little more energy efficient because they are better insulated. Although they use intense heat during cleaning, they also require less energy to cook your food. If you clean your oven only two or three times a year, you will likely save energy by buying a self-cleaning unit instead of an equivalent, regular oven.
Convection ovens that cook by circulating hot air about the food use only one-third as much energy to operate as conventional ovens. They produce further savings through reduced cooking times because the food is more evenly exposed to heat. To operate your oven efficiently, use it only when a smaller or more efficient appliance won't work. Toaster ovens are better for small items, and microwaves not only use less energy, they require less cooking. Crockpots, countertop steamers, and other appliances made just for certain cooking jobs use less energy than heating an entire oven for an extended period.
Operate the oven the least possible amount of time by using the minimum pre-heat time and turning it off toward the end of the cooking time, letting it coast slowly down from its set temperature. When possible, cook several dishes at the same time in an oven, but don't block air flow.
Food cooks more quickly and efficiently when air can circulate freely. Therefore, don't wrap the racks in foil and stagger pans on upper and lower racks to allow for good air flow. Also, the type of pan you choose to cook in can make a difference; with glass or ceramic pans, you can reduce the oven temperature by 25ºF, and the food cooks just as quickly.
With self-cleaning ovens, perform the cleaning cycle right after using the oven to take advantage of it being pre-heated, and only run the high temperature cleaning operation monthly or when really needed.