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Energy Mythbusting

Is it cheaper to have the heating on all day?

Should you keep your heating on all day on low? And what about painting radiators black? We've gone on an energy mythbusting mission, so you can find out if common tricks to cut energy usage really work.


Switch energy now to save £100s

Switching tariff can cut many people's bills by nearly £200 a year. It's the same electricity, same gas and same safety - only service, billing and price changes. Some can save just by changing tariff with their existing supplier.

Your cheapest depends on your personal details - plug them into our MSE Cheap Energy Club to find your cheapest. You usually get £30 dual-fuel cashback, and it'll let you know when to switch again.

We got MoneySavingExpert.com users on Facebook and Twitter to tell us their energy-saving tips 'n' tricks - then we asked the Energy Saving Trust (EST) and British Gas to tell us if these actually work.

Here are the key questions you asked, with their answers below. We have also included feedback from our forum where users have added extra tips.

Should I leave the heating on low all day, or turn the thermostat up and down?

This one divides opinion. The EST and British Gas say you'll save energy, and therefore money, by only having the heating on when it's required. Using a timer is best, because your thermostat is designed to turn your heating system on and off to keep your home at the temperature you set it. However it's a grey area.

Should I keep the hot water boiler on all the time, or turn it on and off as needed?

If you have a gas, oil or LPG (liquefied petroleum gas) central heating system, it will always be cheaper to time the system so the hot water comes on only when required.

Is it cheaper to use radiators or electric heaters?

Electric heaters are one of the most expensive forms of heating. Generally, the cheapest way is using an efficient gas central heating system, with a full set of thermostatic radiator valves, a room thermostat and a timer.

Do phone or laptop chargers still use electricity when they're plugged in, but not connected to the device?

Try to unplug chargers when not in use. A lot of devices draw power when plugged in and not in use. This is sometimes known as 'vampire power'. Using this standby power can be easily avoided by switching devices off at the wall.

Should I run appliances at night?

If you're on an Economy 7 tariff, you'll pay less during the night, but a higher rate than average during the day. But if you're on another tariff, it doesn't make any difference.

MSE tip: This has been answered from an energy use perspective. Before you use an appliance at night, check it's safe. If you're unsure what tariff you're on, check with your energy company. For more help, see Economy 7: Is It Right For You?

Should I set thermostats on individual radiators, rather than using the main thermostat to control all of them?

It's best to have as many controls as possible, so you can fully control the way you want your home to be heated. A room thermostat saves, on average, about £70 a year, whereas having all your radiators installed with thermostatic radiator valves can save around £10 a year. See this guide from Drayton Controls for more on how thermostatic radiator valves work.

Should I turn individual radiators down at the valve, or will it only make a difference if controlled via the main thermostat?

There's little difference. By turning your radiators down or off using thermostatic radiator valves on the side of them, or by reducing your room temperature via a thermostat, you decrease the amount of heat your heating system has to generate.

Please suggest any changes or questions you'd like answered in the Energy mythbusting thread.

Would painting my radiators black or putting reflective panels behind them help?

Where painting your radiators black is concerned, the answer's no. It's best to keep them the standard white, although the difference is not huge. It's more important to insulate your walls to prevent the heat leaking out of your home altogether.

Should I have the gas fire on in the living room, or all the radiators in the house?

There is no one answer for this. It's highly dependent on the heating system you use, and the usage in other areas of the house.

If my heating is on, should I keep doors open or closed for each room?

It's better to keep doors closed for the area you want heated.

Should I leave lights and appliances on, or turn them on and off each time?

Turn them off when you don't need them. Also avoid leaving TVs and other devices on standby.

MSE forum feedback: While turning devices off completely saves energy, the difference can be negligible. So don't bank on this solving all your energy woes.

Should I use a tumble dryer, or place washing on an airer with heating on?

An airer is better because tumble dryers use a lot of energy.

Are halogen heaters cheaper than other portable heaters and central heating?

This depends what you're after. Halogen heaters are directional. Once on, you instantly feel the heat. As soon as you turn them off, the heat quickly dissipates. Convection heaters, electric panel heaters or free-standing electric radiators work by heating the air around them to create a convection current. They take some time to heat a room, but once turned off the heat lingers.

Should I use an immersion heater to heat water, or oil-fired central heating?

Generally, using oil for hot water is cheaper, due to the higher average cost of electricity. However, if you're able to use a lower rate electricity tariff (such as Economy 7, where power is cheaper at night) at the right time, it can work out more cost-effective. This is also dependent on the efficiency of your central heating system.

Is a combi boiler cheaper to run?

The cost is largely dependent on its efficiency. An A-rated combi condensing boiler will cost less to heat the same amount of water as an older, less efficient non-condensing boiler. But combi boilers can be less efficient at heating hot water than other boilers. See this Which? guide for what a combi boiler is.