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Home & garden.

9 November 2021

Are electric heaters eco friendly?

Portable heaters are a great way to deliver a quick heat kick during the coldest months. We explain how they can fit into a sustainable lifestyle
JM
Jake Massey
Fan heater on the floor

Portable electric heaters don't keep the whole house warm like central heating systems do, but they do provide you with a heating boost exactly when and where you need it. They're a helpful companion during frosty days and freezing nights. 

But are they eco friendly? And will you run up needlessly high bills? This comes down to whether you've bought a good model that suits your needs and how you use it. Read on to find out more. 

Checking out our electric heater reviews to find a top-quality heater for the cold months. 

Are electric heaters sustainable?

The conversion of electricity into heat doesn't produce harmful by-products such as carbon emissions at the point of use. This is why you sometimes hear electricity being described as 'clean'.

But while the electricity you draw from a power outlet can be generated using renewable energy sources, electricity generation can still put a lot of CO2 into the atmosphere. 

It depends where you live, but the electricity you use in your home is generated from a variety of sources, including renewables (around 41%, on average), gas (38%) and nuclear (21%). You can't guarantee that you're using renewable power when you switch on your heater because electricity from all sources is mixed-up in the grid. 

Find out more about renewable energy and differences between green energy suppliers.

How to use an electric heater frugally

  • Buy a heater with a thermostat that's proven to work in our lab tests and set the temperature you want. This will mean that the heater isn't spewing heat that it doesn't need to: it will reach a stable temperature and only generate what's needed to maintain this.
  • Buy the heater type that suits your needs. Buying one that doesn't do what it needs to will mean the electricity you're using is wasted, and you're more likely to find yourself relying on central heating to warm you up. A small fan heater can be great when you're getting ready in the morning, but a radiator will provide heating throughout a large room.
  • Use it in conjunction with central heating if you can find the right mix. It can be wise to keep your home heated at a baseline level and use an electric heater to provide warmth during the coldest hours and only in the room you're in.
  • Use the controls that are built into heaters. Your heater might go up to 2kW or 3kW (more on this below), but that doesn’t mean you always need it at that level of heat output. Instead of blasting heat out on max all the time, toggle it to a low setting, such as 1kW or 1.5kW, then crank it up when you need to. 
  • Consider how insulated your space is. You don't want a convector heater just warming up the atmosphere because the air is leaking from your home: this will leave you cold and out of pocket. If you want to get started, then take a look at our guides to insulating your home.

Our guide on how to buy the best electric heater explains how to shop for a great model and highlights some of our top-scoring ones.

How much do electric heaters cost to run?

Most electric heaters have a maximum rated output – usually 2,000 watts (2kW) or 3,000 watts (3kW). Good heaters also have settings where you can adjust heat output – the more choices, the more control you have to get the right temperature without wasting energy.

To work out your costs, multiply the hours you're using the heater with the energy output you're using in kilowatts to get the kilowatt hours used (kWh). This is what utilities companies use to calculate your costs.

Find out what your tariff charges you per kWh and multiply this and you'll arrive at the figure your heater will cost you to run. 

For example, if you use a 2kW fan heater for an hour every morning and you pay 21p per kWh, then you'll be spending £2.94 every week on electricity for your heater. 

Paying through the nose for energy? Compare suppliers with our Which? Switch tool.

Why does a thermostat matter so much?

It hasn't always been mandatory for electric heaters to have temperature sensors, but now it is. This is because of EcoDesign Lot 20, legislation that affected the design of electric heaters in order to create a minimum standard for energy efficiency. Because of this, every heater you buy can detect the temperature of the room and adjust its output to ensure a stable room temperature.

Although this legislation created minimum standards, we go beyond this in our test lab to differentiate heaters with good thermostatic control from the ones with low quality thermostatic control.

It's not easy to manufacture a heater that can detect the temperature easily because heaters' thermostats are so close to the heat source. Thermostats have to account for this when they sense the ambient temperature of the room. There's a lot of room for failure.  

A poor thermostat can lead to a range of bad consequences which increase wastefulness.

  • Poor sensors will mean the heater doesn't adjust its output according to the ambient temperature because it will struggle to detect it. This might mean that it's generating too much heat or not even generating heat at all. 
  • Poor temperature stability will mean that the heater's output drifts from too low to too high, which is not only uncomfortable but will see your bills running up. 

Effective thermostatic control gives you heat when you need it, in the correct proportions. This reduces waste and maximises energy efficiency. 

We've tested smart radiator valves to help you get the perfect temperature for your central heating. Read our smart radiator valve reviews to find the best.

Which is the least wasteful type of heater?

Portable radiator on the floor

We test four types of heater: fans, convectors, oil radiators and oil-free radiators. They each have different strengths and weaknesses. 

The truth is that no type is automatically more sustainable than another and they're all capable of converting electricity into heat efficiently. 

But different heaters suit different users and you can avoid waste by using the heater that best suits your needs.

  • For quick heating you want to use a fan, which generates heat and then blows it around. This means you're warmed up while you're getting ready in the morning, or if you need a boost after coming in from the cold. It would be wasteful and unhelpful to turn a radiator on which takes half an hour to warm the room up if you just need a quick blast.
  • For longer heating convectors, oil and oil-free radiators excel, and warm the whole room evenly. Oil radiators even provide heating when they're turned off because their oil, which functions as a heat reservoir, retains heat.
  • For heating that makes you toasty you'll want a fan that blows hot air on you, or an oil or oil-free radiator that provides thermal radiation that heats objects (including your body) directly.
  • For quiet heating you'll want a radiator or convector, because a fan could make such a racket that you don't want to use it. 

How do I buy an eco-friendly heater?

Be careful if you're thinking about buying a second-hand heater. This requires trust in the seller and checking on your rights, because faulty or broken heaters can be wasteful at best and dangerous at worst. We've seen heaters being recalled because they're a fire risk when their components fail. 

Don't buy a heater that was designed before 2018 which doesn't have a built-in thermostat. A heater like this couldn't be sold new now because it's so inefficient. 

  • Look at our scores Our test programme values heaters that heat quickly, thoroughly, with minimal energy consumption and with good thermostatic control. This means that our highest-scoring heaters are most likely to be the least wasteful and our lowest scoring will have you wanting more while they guzzle electricity. 
  • Don't fall for a false economy You can buy a heater for as little as £15, but this isn't really worth it – use it for an hour every day and you'll probably pay that in bills after a couple of months or less. Don't buy a cheap heater that can't detect the air temperature and then wildly overcompensates with excess heat generation – you'll pay for it.
  • Buy a heater with a timer and with heat outputs you can toggle between manually You don't want to be stuck with a heater running at 2kW if 0.8kW would do for a small room. The more settings there are, including a timed switch-off, the more control you'll have to optimise your usage.
  • Be wary of so-called 'eco' settings because these are often just a lower kW settings This is good to have, but a heater with four adjustable outputs is better than a heater with two where one is called 'eco'. It's better to look beyond the marketing hype here.  

Insulating your space is crucial because most heaters work by convection most of the time and you don't want your hot air floating off into the horizon. The better your home holds on to warmth, the less electricity your heater needs to draw from the mains to try and keep up. 

Finally, think about your tariff. Although heaters are clean because they don't create emissions at the point of energy conversion, they still rely on energy from the National Grid. Whether your electric heater relies on fossil fuels or renewables is beyond the control of the heater manufacturer. 

Find out how to make savings throughout your home with our guide to 10 ways to save your energy bills.

Can I repair my electric heater?

There's a market for spare parts for some electric heaters. Components such as bezels, heating elements, thermostats, castor wheels and more may be available. For example, when we checked in October 2021, spare parts for some DeLonghi heaters could be bought online.

But knowing what has gone wrong with your heater can be hard to work out – disassembling it can be harder yet. And, if it's within warranty, then taking your heater apart will affect your rights depending on the terms of use. If you aren't confident in repairing your heater, you should hire an electrician or take it to a repair shop to have it looked at.

Right to repair laws don't cover electric heaters at the moment, so spare parts and access to components aren't guaranteed by law.

How do I dispose of an electrical heater?

According to Recycle Now, around one million tonnes of electrical and electronic waste are generated every year. Every item that has either a plug, a charger, batteries or carries a crossed-out wheelie bin logo can be recycled - this includes electric heaters.

You can take your old heater to your local recycling centre or see if your local council offers a household collection service for small electrical items. Double check the weight and dimensions of your electric heater to see if it qualifies. Some heaters are small desk-sized gadgets, while others are large units.

It's especially important to dispose of an oil radiator carefully because oil pollution is ecologically destructive and oil that leaks on to the ground will have a suffocating effect on plants and creatures. 

Oil is treated as a hazardous waste and needs to be disposed of locally at your nearest recycling centre that accepts it. Your council should offer advice online about where you can drop it off.

If you bought a used electric heater, read our guide to your rights when buying second-hand goods

Or, find out more about how to recycle electrical items.