Microwaves ovens are the most common small appliance in North American kitchens, as well as the most frequently used. Using a microwave will save you money. Not only are they fast and efficient, but they use up to 65% less energy than conventional ovens and have the added benefit of not heating up your kitchen.
Microwave ovens work by using high-frequency radio waves to penetrate the food, rather than the heating space or cookware. Once in the food, these radio waves heat the water molecules. The result is a faster cooking time and less energy expenditure when cooking. As you've likely found out, microwaves work best when cooking small portions, saving up to 80% of your time and electricity expenditure.
For example, when cooking a typical casserole, a microwave oven is the most energy efficient choice, using only 0.36 kWh. This costs about $.03, which is far less expensive that an electric oven ($0.16), an electric convection oven ($0.11), a gas oven ($0.07), an electric frying pan ($0.07), a toaster oven ($0.08) or a crock pot ($0.06). It is also much quicker than the alternatives; taking only 15 minutes. However, microwave ovens are not at their most efficient when used to thaw or cook larger portions of food.
Microwaves can vary in size, ranging from 800 watts to 1500 watts. But almost all basic microwaves are created equal when speaking about energy efficiency. The higher-end and newer models offer homeowners a wide range of features that can improve both energy efficiency and cooking power. Temperature probes, moisture sensors and variable power are all options available on newer models.