Microwaves

This guide covers microwaves, including combination microwaves which also have conventional heating methods built in.

We look into energy efficiency, mainly in comparison with other cooking methods, and question whether the potential energy savings are worth the costs of manufacture.

We also offers some advice on how best to dispose of your unwanted microwave, try to separate fact from fiction when it comes to health risks, and look at the issues related to microwave meals.

Highlights from the score table above

Arms and military supply – Eleven companies on the table were marked down in the Arms and Military Supply category. Companies get marked down here for activities such as supplying weapons, equipment, technology or systems to the defence industry, or for investing in such activities. The microwave technology that microwave ovens use was actually invented by the US defence firm Raytheon in the first place, while they were developing radar systems.

Conflict minerals – Almost all of the companies in the table lost marks under Human Rights and Habitats and Resources because they did not have an adequate policy to prevent the sourcing of conflict minerals for their products.

The only companies that did not get our worst rating for conflict minerals were Siemens, Samsung and Panasonic, which all received a middle rating, and HRG Group (Russell Hobbs) and LG which received best ratings.

Conflict minerals sourced from the Democratic Republic of Congo and surrounding countries are a major issue in the electrical industry. Profits from their sale has frequently been found to fund wars and arm militias. The mining practices are usually also very unsustainable, and forced and child labour is a common problem.

Pollutions and Toxics – Every single company on this table lost marks under Pollution and Toxics. This is mainly due to a failure to phase out a number of frequently used substances in the electronic industry that are considered highly toxic.

Energy Efficiency

Microwave vs. ovens

Unfortunately, there is no simple answer to the question of whether microwaves provide an efficient way to cook and heat food than ovens – it is all about how you use them.

If you want to boil a cup of water it is actually more efficient to stick to your kettle (although remember to only boil the water you need).

On the other hand, if you want to heat smaller portions of food it is definitely better to use a microwave than a conventional oven as it can be around 80% more efficient.

As our product guide to cookers points out, ovens are only 10-12% efficient because they have to heat the entire oven space, whereas microwaves heat the water in the food directly.

While microwaves are more efficient than ovens, the difference decreases as the amount of food increases. It also depends on whether your oven is gas or electric (see oven guide).

Confusedaboutenergy.com provides a comparative list of the typical energy usage of cooking different types of food with either a microwave or conventional cooker

Is the cost of manufacture worth the savings in household energy?

However, cooking is an area where choosing the most efficient methods may not significantly impact on the overall energy usage of a household. 2018 UK Government data found that, on average, cooking represents 6% of household electricity usage.

Taking that into consideration means that, even if you can save energy by using a microwave for some cooking processes, it is not necessarily worth the energy and resources used to manufacture that microwave in the first place. A recent study suggested that the energy used to manufacture a microwave is about 494 kWh – a fifth of its total lifetime energy use – and has other environmental impacts as well.

A Microwave should last around 7-9 years. Interestingly this is about 6-7 years shorter than the lifespan of a microwave 20 years ago. Our advice is that if you have a microwave then by all means use it, but if it breaks or you don’t yet have one, perhaps question whether you really need one, or consider buying second hand.

Energy labels

Comparing energy efficiency between microwaves can also be a little tricky. Unlike many other household appliances, microwaves are not required to carry an energy label.

However, one tip is to either avoid getting a microwave with a digital clock or, if it does have one, make sure you turn it off in-between uses – unless, of course, you are using it as your clock! Reports on this vary, but some have suggested that if a microwave with a clock is plugged in at all times, overall more energy will go towards powering the clock than heating food. The EU should extend labelling laws to cover all products that consume energy in use.

Combination Microwave ovens

A combination microwave-oven may be an option if you have limited space and are looking to replace your oven. These are single units which contain both conventional and microwave heating mechanisms. This means that you can still get the energy-saving benefits of cooking with a microwave, without the extra impacts of manufacturing, transporting and disposing of a whole extra appliance.

Disposal

When it comes to microwaves, how you dispose of an old one can be just as important as how you choose your new one or use your current one.

According to Waste Connect, electrical and electronic waste is one of the fasted growing waste streams in the UK. A recent study suggested that, in 2005, 184,000 tonnes of electrical and electronic (EE) waste was produced by discarded microwaves and predicted this to rise to 195,000 tonnes by 2025. Electrical waste can cause harmful toxins to leak into the environment.

You can prevent your microwave ending up in the landfill by using the Recycle Now website to find your nearest recycling centre that will accept your microwave.

If you are purchasing a new microwave then the EU ‘WEEE’ directive states that the company you are buying from must provide a ‘take-back’ service for your old microwave where it is the company’s responsibility to dispose of it correctly (this also applies to other household appliances and electrical items). If your microwave is still in working order than you can also sell it or donate it.

Microwave meal packaging

The microwave ovens themselves are not the only issue to think about. With the microwave came the microwave meal, packaged in a plastic tray with a plastic film. Not all local authorities collect these plastic trays. Where they do, black plastic trays make it difficult for sensors at recycling plants to pick out the containers against the backdrop of a conveyor belt. This leads to a high proportion of black containers being mistakenly sent to landfill from the recycling plant.

Some companies have started to develop ‘compostable’ alternatives to plastic microwave containers – these are designed to be recycled with food waste.