Britain’s old houses leak heat, which means needless spending to keep them warm. Here are some ways to cut costs

B ritain’s old homes are leaking – and costing us a lot of money. As gas and electricity prices go up this weekend, there’s a renewed focus on insulating our homes to prevent heat loss and avoid spending needlessly on energy. But where can most consumers start in order to take control of spiralling bills?

The UK’s housing stock is the oldest and least energy-efficient in Europe – more than half of it was built before 1965. And 20% before 1919. As a result, many homes are poorly insulated, and owners are paying a premium for their energy that could be avoided if measures were taken to stop heat escaping.

Will Hodson, who founded the Look After My Bills switching site, last week launched a campaign to highlight the need for insulation at a time when switching provider is not enough to save consumers from rising prices. Almost 15 million homes in the UK need loft or cavity wall insulation, he says.

“Our old homes are part of our cultural heritage. But retrofitting them, and upgrading them, should be a part of our future,” he says. “We should all look at insulating our homes as being as natural a process as feathering one’s nest. Energy prices have never been higher, and it’s a fact that the savings associated with energy efficiency investments have never been higher, either.”

Hodson advises homeowners to first look at the EPC (energy performance certificate) rating of their home, which gives a guide as to how energy efficient a property is when it comes to things such as flooring, lighting, the roof, walls and piping. It recommends what measures could be taken to make the property more efficient, from draughtproofing to external wall insulation.

However, the EPC applies to typical households and may not be tailored to how you use your home.

Loft insulation will be the first step for many, as it can be affordable and straightforward to put in place. Uninsulated homes can lose up to 25% of heat through the roof, according to the Energy Saving Trust (EST).

Installing 270mm of insulation, in a home with none, can cost between £455 and £640, depending on whether it is terraced, detached or a bungalow, says the group.

It is possible to do it yourself, saving labour costs, by using rolls of mineral wool material in between the joists of the loft. The savings stretch between £330 and £590 a year, according to the trust, so the work soon pays for itself.

Where there are damp problems, or a flat roof, a professional will need to do the job. Rafters can also be insulated using boards with material on them or a special foam, although much more expensive. Installers can be found via the National Insulation Association.

It is estimated that a third of the heat in uninsulated homes escapes through the walls. So the first thing a homeowner must do is identify the type of wall in their property, which dictates how it can be insulated.

Cavity walls have insulation materials – such as mineral wool and polystyrene beads – injected into them through drilled holes which are then sealed. The EST puts the costs – it must be done by a professional – at £580 for a mid-terrace house, running up to £1,800 for a detached house. Savings range from £235 a year for a terraced house to £690.

Solid walls can have insulation boards fitted to the inside, or a layer of material to the outside, which is then covered in cladding or plaster. The cost is considerably more, according to the EST. On a typical three-bed semi-detached house, it comes in at about £12,500 for external insulation, and £8,500 for internal. The savings are estimated at between £315 a year for a mid-terrace, to £930 for a detached home.

Lowering, or at least managing, the cost is possible by insulating when you are having other work done, such as redecoration, new windows or solar panels fitted. Consumers are advised to get three quotes before they begin.

Floors come in different forms. In newer homes they are usually made of solid concrete, which can be insulated when floorboards need to be replaced. Insulation panels, or boards, are used, with the thickness kept to minimum to avoid having to change door openings due to a shift in floor height. The Centre for Sustainable Energy says the costs start at about £1,000 and will save up to £70 a year.

Older homes are more likely to have suspended timber floorboards. These can be lifted, and mineral wool insulation placed between the joists. The cost comes in at between £1,600 and £2,900, according to the EST. Suspended floors can also be insulated by robots that spray on insulation. Savings range from £60 to £155.

For homeowners with a bigger budget, a more elaborate plan is recommended. This should start with hiring a retrofit assessor (at a cost of between £250 and £400). They will draw up a plan to reduce your energy consumption, carbon emissions and improve comfort and health, says architect Sara Edmonds, who chairs Architects! Climate Action Network, a group that aims to tackle climate and ecological problems in construction.

A retrofit coordinator (at a cost of about £500) can then oversee a project to update the property from start to finish.

Edmonds says that EPC assessments do not go far enough in understanding what is needed to properly retrofit a house. These include ventilation, the condition of the building, existing insulation or even whether the owner dries their clothes inside.

Tackling insulation in the wrong way can lead to more problems being created, she warns.

“For example, if you replaced a broken old window in a bathroom with a new better-performing window, or close up any drafts or leaky openings in the walls around the toilet waste pipe, or other pipes without also improving ventilation, you may find that you exacerbate any condensation build-up, and therefore mould growth, which can be harmful to your health and the building itself,” she adds.

“Single measures – like just changing windows or adding external wall insulation – should not be carried out in isolation without understanding how the whole building works.”

The cost of insulation materials has been hit by the current economic instability, with some prices up by 50% from a year ago, and delays being reported in getting equipment.

One installer, Craig Stewart, of Mersey Eco Grants, tells the Observer the price of the specialist material used to fill cavity walls has increased by half over the last 12 months.

He also says some items, like boilers, have had to be ordered up to two months in advance. Consumers are facing the rising costs of materials, labour and increased demand following the pandemic.

Government figures show materials were up across the board by 26% in the year to June.

The pandemic also led to a shortage in electrical components from China, where production has slowed due to Covid.

“Last year, we could walk into merchants and collect a boiler, but now you have to order in advance,” says Stewart. “They just don’t have them readily available.”

Timber, cement and plasterboard have all gone up in price due to the rise in energy prices, which particularly affects producers of construction materials, who are heavy consumers of oil and gas.

Homeowners getting work done have been warned that estimates may change as the cost of materials is constantly fluctuating.

This is exacerbated by the skills shortage, both to do jobs and also to transport the materials across the country.

In addition to this, the construction sector has warned that new building regulations introduced in June, aimed at improving energy efficiency, will increase the price of extensions and loft conversions.