What you should and shouldn’t do to cut your home energy bills

Sort It: Turning off the heat in rooms you don’t use and insulating the rafter space in your attic are not the way to go

Attic floors should be insulated to stop heat escaping from the rooms below, but there's no need to insulate the rafters.
Attic floors should be insulated to stop heat escaping from the rooms below, but there's no need to insulate the rafters.

There is a lot of advice about the best ways to save energy and keep your home heating bills low this winter. While there are many helpful tips, not all the advice is good. And some of it might even cost you more in the long run. I chatted with home energy and retrofitting expert Fergal Cantwell from EnviroBead to get his advice about what you can do to save money and what the energy-saving myths are.

You should insulate the rafter space in your attic

Insulating your attic is one of the most effective ways to keep heat in your home. It’s a relatively inexpensive job but one that will reap immediate benefits.

Insulating between the rafters is unnecessary unless you use the attic space as a room. “Attics are supposed to be cold,” says Cantwell. Attics are insulated to prevent heat from escaping from the rooms below into the attic space. The ceiling level is the only area that needs to be insulated.

For a three-bed semi-detached home with an attic size of about 50sq m (538sq ft), the grant allowance is €1,300. The grant covers approx. 80-90 per cent of the total cost of the work. The work should take no longer than half a day to complete.

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Turn off the heat in rooms you don’t use

“I don’t agree with this advice,” says Cantwell, who recommends heating these rooms to a low level rather than turning the heat off altogether. “It’s important to have some heat in a room even if it’s not being used,” he explains. Otherwise, there’s a risk that condensation, dampness and mould will become a problem. Blocking up air vents to keep the cold out is something else Cantwell warns against doing. Proper ventilation is essential to maintain good air quality.

A better solution is to fit Thermostatic Radiator valves (TRVs) to your radiators. This simple and low-cost measure will allow you to control each radiator individually. ‘The more control you have over your heating system, the more efficient it will be.’ Says Cantwell. TRVs typically have settings from 1-5. For rooms you’re not using, you could set the control to 1 or 2 to take the chill out of the room.

Night-rate electricity is significantly less expensive than day-rate. So the advice is to run appliances like dishwashers, washing machines and dryers during the night after you go to bed.
Night-rate electricity is significantly less expensive, but machines such as dishwashers and dryers can cause fires if faulty, so it's better to run them first thing in the morning rather than late at night while you sleep. Photograph: Donal Murphy

Run your appliances during the night

Night-rate electricity is significantly less expensive than day-rate. So the advice is to run appliances like dishwashers, washing machines and dryers during the night after you go to bed.

However, Cantwell suggests you do this with caution. Dishwashers and dryers, in particular, can cause fires if faulty. Instead, he suggests using them first thing in the morning while you’re awake and able to deal with a problem if it arises.

Night-rate or off-peak electricity runs from 11pm to 8am during winter. And, in the summertime, until the clocks go back in late October, the night-rate hours are midnight until 9am.

Use the dishwasher instead of hand washing

You’ll use more hot water when hand washing than you will using a dishwasher, making it a less energy-efficient and more costly way to wash your dishes.

Bear in mind that the higher the rating of your appliance, the more energy efficient it will be. If you have an old dishwasher, it may well be worth replacing it with a new model with as high a rating as you can afford. “It’s always better to spend a bit more to get a better-rated appliance, says Cantwell. It will save you money in the long run.

If drinking endless cups of tea is your strategy for keeping warm this winter, remember that the kettle is one of the most expensive appliances to run. 'Anything that gives instant hot water is costly to run,' says Cantwell. Often the kettle is filled to the brim to make a single cup of tea, which is a huge waste of energy.
If you drink lots of tea to stay warm, consider installing a boiling-water tap so you don't have to use a kettle. Kettles are very expensive to run. Photograph: Ruth Maria Murphy

Load up on hot drinks to stay warm

If drinking endless cups of tea is your strategy for keeping warm this winter, remember that the kettle is one of the most expensive appliances to run, says Cantwell. Often the kettle is filled to the brim to make a single cup of tea, which is a huge waste of energy.

An easy remedy is to consider installing a boiling-water tap. Not only will it give you instant boiling water and save you space in your kitchen, but it will also save on energy costs. Quooker claims that the cost of using its hot tap is one cent per litre delivered, or approximately three cents per day. The cost of boiling a full kettle (which typically holds 1.5 litres) is around 2.5 cent per boil. This would suggest that a Quooker could save users a significant sum, particularly those who regularly boil their kettle.

Electric showers are another expensive item to run. “If you can replace your electric shower, consider doing it,” recommends Cantwell. If not, you should severely limit the length of time you spend in the shower.

Insulate your radiators

This is a tip I read recently that made me smile. The rationale was that the paint would insulate the radiator and trap the heat to keep it warm. But the whole point of radiators is to let the heat out. Painting radiators will make them work less efficiently and may also void the manufacturer’s warranty.

“Covering radiators in any way is a terrible idea,” says Cantwell. He also strongly advises against radiator covers. Radiator covers stop radiators from working efficiently. Because the air has to pass through a slot or grille, the thermostat will struggle to read the temperature. This causes the radiator to run on full power when it doesn’t need to, which will cost you money. If you have radiator covers in your home, you may want to consider removing them.