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Oct 29, 2024

What is the most efficient way to use central heating? Your energy questions answered | Energy bills | The Guardian

As the clocks go back, our experts answer queries about gas and electricity use, be it for drying clothes, doing the washing up or sorting out the heating The clocks change this weekend, and suddenly

As the clocks go back, our experts answer queries about gas and electricity use, be it for drying clothes, doing the washing up or sorting out the heating

The clocks change this weekend, and suddenly there will be no escaping the fact winter is coming. The return of darker, colder nights also means that keeping energy costs down becomes a priority for many Britons.

Although energy bills have eased from recent highs, the latest price cap revision by Ofgem, the energy regulator for Great Britain, was a rise of almost £150 (just under 10%) to the equivalent of £1,717 a year for an average dual-fuel household paying by direct debit.

With energy bills on everyone’s mind, we asked readers to contact us with their questions big and small about domestic gas and electricity use, as well as other energy-related problems, so we could put them to the experts.

Much has been made of the money-saving benefits of owning an air fryer, but I can’t find any useful comparisons with a gas oven.

The popularity of air fryers – which are essentially counter-top fan ovens – exploded during the cost of living crisis, with a recent survey suggesting they are now the third-most used kitchen appliance in the UK after toasters and microwaves.

Air fryers are “a great way to cook smaller portions of food” because you don’t have to waste energy heating a large oven, says Elise Melville, an energy expert at the price comparison site Uswitch. “Although they use a similar amount of power as a conventional oven, they are cheaper to run as they can cut cooking time by as much as half. A 1.5kW air fryer, for example, would cost 18p to run for 30 minutes.”

However, a conventional oven can be very useful when cooking for large gatherings that require the use of both shelves, she adds. “Gas is much cheaper than electricity, so a 2kW conventional gas oven would cost 11p if used for an hour, or 5p for a half hour. In general, a gas oven is likely to be cheaper to use than an air fryer, unless you’re cooking a small amount of food for a short time.”

Is it cheaper to boil the kettle to do the washing-up or use hot water from the tap?

The answer depends on whether your water heater is powered by gas or electricity and the amount of water being boiled. “Electric kettles are generally more efficient at heating water than most hot water systems, so for smaller volumes of water this may work out cheaper, but don’t scald yourself,” Melville warns. “For larger volumes, a gas-powered water heater will be a more sensible choice, and you’re likely using more water than a kettle can heat in one go.”

What is the most efficient way to use central heating? Set it at a lower temperature for longer or at a higher one for less time? Should it come on first thing or keep the house warm overnight?

As temperatures drop, so begins the annual debate about when and how to use the central heating. The first step is to make sure your room thermostat is set to the right temperature, with most people opting for 18-21C. If you want to save money, reducing the temperature by 1C will save you about £90 a year in Great Britain, according to the Energy Saving Trust, the social enterprise that offers advice on energy efficiency.

It says that, in general, it is useful to have your heating come on half an hour before you get up and turn off 30 minutes before you go to bed. (Electric blankets are a good option to avoid putting on the heating at bedtime; many models have a timer.)

Is it more efficient to leave the heating on all day? If you have a boiler, then the answer is no. It is better for your bills to have it come on when you need it, the Energy Saving Trust says. However, if you have a heat pump, you can save money by leaving the heating on all day.

I keep seeing the “eco mode” on washing machines being touted as a great way to save money. But my eco cycle is locked at 40-60C and takes more than three hours. My “normal” wash cycle can be done as quickly as 70 minutes and I can turn the temperature off. Would this be cheaper?

Check your washing machine’s instruction manual as it might have details of the energy and water usage for each setting. “Your eco cycle will likely use its longer runtime to soak off the dirt, but the fact that the washing machine will be using the motor more over its runtime will push up the energy costs,” Melville says. “Most of the costs of running a washing machine come from heating the water. Using a cold water wash may work for some laundry, but you may need to use the eco mode for deeper cleaning.”

I live in a 1910 semi-detached house with gas central heating. It has double glazing and an insulated loft. However, it is still cold and the heating bills are high. What else can I do to reduce my energy bills?

Turning down the temperature of your combi boiler makes it work more efficiently and is estimated to save the average household about £65 a year. Combi boilers work best when they heat the water that goes to the radiators at 60C or below (called the flow temperature) – but in most homes they are set at 70-80C.

There is a step-by-step guide on how to adjust the temperature on the charity Nesta’s money saving boiler challenge website, says Richard Fitton, a professor in building performance at the University of Salford.

The best way to insulate a room without causing damp or mould? The house was built in the 1990s, so we think there is already cavity wall insulation.

“If your cavity wall insulation is performing well, then extra wall insulation may not represent good value,” Fitton says. “There are still other insulation measures you may wish to look into: foil panels to the rear of radiators have been proven to make savings, while curtains and blinds can also be effective.”

He adds: “The addition of draught strips to your windows and doors may help, but keep ventilation in mind … Floor insulation can offer savings but is quite costly and disruptive; a substitute could be a good-quality underlay and carpet, which will help. A room with loft space above would obviously benefit from insulation in the roof space, which is very cost-effective.”

We live in a near 200-year-old, three-storey terrace house and need a new boiler. We don’t have any outside space, so can’t install a heat pump. What is our next most environmentally friendly and economical option?

“There are a couple of options. There are what’s known as exhaust air heat pump systems which can be installed inside a property, with no external units, but this will be quite a significant cost as the installation is more involved,” Fitton says.

“Otherwise, you could look towards an electrical-based system – this will be possibly more expensive to run, as gas is a lot cheaper, but as the power grid cleans up over the year, these will become increasingly low-carbon. If all of these don’t suit, you could also upgrade to a new boiler – it is likely to be more efficient than the one you have, so it could still make you some small energy and carbon savings. Whenever we talk about changing heating systems, you should always consider insulation.”

In winter I dry my family’s clothes inside, but I don’t know whether to buy a heated airer or a dehumidifier. How do the costs compare? What are the pros and cons of the different appliances?

Many households try to avoid using their tumble dryers on cost grounds, but the flipside is wet clothes hung on radiators and drying racks. As they dry, the moisture is transferred into the air, making rooms damp and creating condensation on windows and, occasionally, the walls.

Dehumidifiers, which draw excess moisture from the air, are a good solution. With the average appliance using 185W, they will only cost you 5p an hour in electricity, Melville says. By comparison, a 300W heated airer costs 7p to use for an hour under the current energy price cap, while a tumble dryer, which uses 2.5kWh of energy each cycle, would cost 61p. “Using a heated airer to dry your clothes and running a dehumidifier to get rid of the moisture would cost you 12p an hour, which is much cheaper than a tumble dryer.”

I struggle to keep the temperature at 18C in my house. I’d love to retrofit it, but how do I finance it when even government grants and loans require payments upfront? Also, how do I find an installer I can trust?

The Energy Saving Trust is a good place to start. It will help you to locate finance that will match your requirements and provide sensible guidance for a number of different measures, Fitton says. “If you choose to use a government-backed scheme, they will use approved contractors under a formal quality-assurance procedure such as TrustMark. It may also be worthwhile to check with your local authority, as it may have specific funding pots available to you.”

What advice do you have for people who have already limited their energy use as much as they can? I never put my heating on, take short showers, don’t use my oven and do a 30C degree wash once a week. I don’t have a dishwasher or tumble dryer but am thinking of getting rid of my freezer.

If you have taken extreme steps but are still struggling to manage, talk to your energy supplier. You may qualify for an energy help scheme – there is a guide on the Uswitch website. If you receive certain benefits, you may be entitled to cold weather payments. Also, check to see if you can get help from your local council’s household support fund.

“The average freezer uses 279kWh of energy a year, which at current electricity prices would cost you £68 to run,” Melville says. “Getting rid of your freezer would save you money on your energy bill, but you need to factor in the cost of more frequent shopping trips, and potentially wasting food.

“You could try using an electric blanket for warmth instead of heating the whole house. Even if you rent your home, you can switch energy tariffs, so it’s worth running a comparison to see if you would be better off on a fixed deal.”