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Microwave ovens





Microwave ovens cook from the inside out by vibrating the water molecules in the food which produces heat. They are very cost effective when cooking or reheating meals, baking potatoes or even making fudge! EcoFrenzy shows you tips on how to save money, energy and the environment when using a microwave oven.

Money saving tips

Microwaving frozen meals

A typical 500g frozen meal costs 4.8p to heat up, whereas the same meal heated in an oven will cost 55p. That means if you heat 1 frozen meal a week in the microwave oven it could save you £26.50 per year (= 24kg CO₂)

Electric hob versus microwave

Boiling vegetables in water uses up to 4 times more energy on an electric hob than in a microwave oven, saving up to 14.5p per time. If you microwave vegetables 4 times a week this will save around £31 per year = 27 kg CO₂.

Baking potatoes

Baking 2 medium sized potatoes in a 2KW electric oven for 1 hour costs around 68p. Cooking the same 2 potatoes in a 1200W microwave oven for 11 minutes costs just 7p. If you baked 2 potatoes once a week in your microwave oven you would save £32 = 29kg CO₂.

Environmental tips

Avoid spills in the microwave

Spills will absorb energy waves just as readily as the cooking food. Microwave ovens operate more efficiently when the interior is clean.

Energy efficiency

Microwave cooking can be more energy efficient than conventional cooking because foods cook faster and the energy used only heats the food, not the whole oven compartment.

Clock and standby function

The microwave oven clock and standby function can consume a significant amount of electricity, even when the oven itself is not in use. It could be consuming most of its energy when not actually cooking, it may be better to unplug your microwave oven when not in use.

By unplugging your microwave when not in use can save you electricity

Reheat small meals

For smaller meals, reheating them in a microwave oven will save energy. It is estimated that you can reduce the energy used in cooking by as much as 80% when using a microwave oven instead of a conventional oven.

Percentage energy efficiency of a microwave oven

About 65% of the electric energy used by a microwave oven is converted to microwave energy which heats the food. This is considerably more efficient than a conventional electric oven which may convert as little as 10%.

Try and avoid defrosting food in a microwave oven

Defrosting food in the microwave oven is convenient, but with a bit of forethought you can do this using no energy at all. Just leave it out overnight and it will be defrosted the following day!

Leave food out overnight to defrost instead of using your microwave

Is there a problem when microwaving food in plastic containers?

There is concern that microwaving food in plastic containers can cause toxic chemicals to leach into the food from the plastic. To be on the safe side we suggest you transfer food into glass or ceramic containers labelled ‘safe for microwave oven use’.

Microwave ready meals

Microwave ready meals can be energy-intensive products in terms of their food miles, the packaging used and the food processing involved. Chris Goodall, in his book ‘How to live a low-carbon life’, estimates that convenience food manufacturing may be responsible for three times as much CO₂ output as home cooking.

Is micro-waved food safe?

Microwave ovens cook food with waves of oscillating electromagnetic energy that are similar to radio waves but move back and forth at a much faster rate. According to the US Food and Drug Administration, microwave energy is changed to heat as it is absorbed by food, and does not make food radioactive or contaminated.