Most consumers already know that microwave ovens use less energy than conventional ovens and stoves. In our earlier article entitled "What are the Benefits of Microwave Cooking?," we touched lightly on the energy-saving perks of these machines, but now we want to show you how those savings actually happen.
How Do Microwaves Actually Cook?
Microwave ovens transfer heat more efficiently by directly heating up the water in the food. This heat energy transfer rate is about 30% to 80%. On a stove top, the heat transfer time from the burner is much less — 12 to 14 percent of the heat energy goes into the food you’re cooking.
In addition, the quality and type of cookware you use also determines the rate of heat transfer. What you’re cooking also effects cook time. While it has been pointed out that water boiled on a stove top actually takes 25% less energy than a microwave, it’s not the same stuff as a bowel of frozen vegetables or a serving of lasagna or a few strips of tasty bacon.
How Much Energy Can You Save with Microwave Cooking?
According to United States Department of Energy data from 2014, cooking accounts for two percent of an average home's energy use. So, on a $200 monthly electric bill, about $4 is going to cooking.
A rough comparison of appliances suggests that using an oven for one hour every day for thirty days cost $4.80 while a microwave costs just 90¢. That’s a good percentage reduction, and the amount saved does add up over the course of a year. But there’s more to it — especially when you consider the energy costs associated with cooking that affect the other ways your home uses energy.
How Can Microwave Cooking Help Me Save Energy in Other Ways?
Here's the key principle: microwave ovens don’t produce a very big heat load for your air conditioning system during the summer. Stoves and ovens do. After all, they’re meant to get hot enough to cook food.
In a microwave, only the food, the container, and a small area of the microwave oven actually gets hot. On a stove top, burners must come up to temperature (up to 400° F or 204° C) and then take time to cool down after cooking is finished.
Admittedly, this might have little noticeable impact most of the time. But on really hot days, using multiple burners could make being in your kitchen just miserable by adding extra heat and humidity to your home. A 350° F (177° C) oven pumps wasted heat into your kitchen that can last for hours, adding to your home’s heat load and requiring your air conditioner to run longer.
What are Other Benefits of Microwave Cooking?
While using kitchen exhaust fans and air purifiers have been shown to effectively reduce these indoor pollutants, it doesn’t eliminate them entirely. Microwave ovens, meanwhile, emit “substantially lower” amounts of pollutants when cooking that aforementioned lasagna or bacon compared to using an electric or gas range.
By using a microwave oven instead, you avoid exposure to pollutants, and you also save some energy since you won't run exhaust fans and air purifiers as often or for as long.
What do you like most about microwave cooking in your home? Share with us in the comments!