The energy-related differences between the various ways to cook and bake food usually have very little to do with either the device or its fuel. Although there may be incremental energy savings between different devices, the overall energy used to cook and bake food in most homes is relatively small—$50 to $75 per year on average. There are presently no ENERGY STAR standards for these appliances.
The expected life of most ranges and cooktops is 14-20 years; microwaves should last about 10 years. These appliances are usually fairly reliable over their expected life; an estimate for repairs of several hundred dollars might suggest replacement. Many newer models have additional features and approaches to heating food. When buying range or cooktop replacements, ask about:
Microwaves are slightly more energy efficient for some cooking tasks, but their main advantage is faster cooking time. The higher the wattage, the less time it takes items to be heated. When selecting a microwave consider the intended uses in order to properly size the unit.
There are a few things you can do to make cooktops, ranges, and microwaves work as efficiently and safely as possible.