Is it finally time for a home ‘eco-over’?

From new windows to insulating the loft, Sarah Lonsdale on the five best ways to spend your £5k Green Homes Grant

In his mini-budget on Wednesday, Rishi Sunak, the Chancellor of the Exchequer, pulled a green rabbit out of his hat. The Green Homes Grant scheme will offer householders up to £5,000 to spend on energy-efficient home improvements – such as insulation, low-energy lighting, double glazing and draughtexcluding doors.

Green buildings experts have cautiously welcomed the plan, which will start in the autumn. “This is a real opportunity to reduce thousands of homes’ carbon emissions,” says sustainable buildings researcher Kate de Selincourt.

“But retrofitting older homes can go wrong in all kinds of ways,” she says. “Simply throwing up insulation isn’t necessarily the right thing to do. We have seen disastrous results, with damp problems increased and indoor air quality decreased after poorly installed insulation, so it’s vital you get the right treatment for your home.”

Homeowners should therefore proceed carefully and not waste money on “improvements” that may be redundant in a few years’ time.

With grants available from September, and a likely rush on supplies of energy efficiency products and materials, it’s good to get started now on a plan for your home so you’re in a position to secure materials and labour as demand soars in the autumn.

Here, then, are five ways to make the most of “Rishi’s green five-grand”.

Get the house greenstamped Cost: £500

glazing, stop. “Get a proper survey done,” says de Selincourt. “It’s worth spending between £400 and £600 on a properly trained retrofit designer who can advise on what’s best and help you write a ‘whole house’ plan. Decide what the zero-carbon version of your home would look like. Even if you’re not able to do everything straight away, you know what you can spend that first £5,000 on and it won’t be wasted.”

Manchester-based Carbon Co-op offer this kind of service, but to find something similar close to you, insert your details online at carbon.coop/ portfolio/home-energy-assessment. Infra-red photography or “smoke guns” pick up cold spots, and to show you where your home is leaking heat.

“Make sure you know how your home is ventilated, how air moves around it. But also check for general wear and tear. If the gutters are leaking then wall insulation will probably make damp problems worse,” says de Selincourt.

Upgrade your insulation Cost: £500

When done well, insulation is a very cost-effective way of reducing your heating requirements. The most common forms are loft insulation (£300-£400), cavity wall insulation (depending on the house, around £500), or solid wall insulation for older buildings (upwards of £500).

Dr Jan Rosenow, an energy efficiency expert and Europe director of the Regulatory Assistance Project (raponline.org) says that loft insulation is a “no-brainer” and one of the simplest ways of reducing your heating bills. He advises to go with an insulation firm with a good track record, and references from customers you can take up.

“With this kind of subsidy scheme, unfortunately there will always be the odd unscrupulous builder trying to take advantage, so you need to go with a reputable firm,” says Dr Rosenow. He adds that underfloor insulation in suspended timber floors can also be hugely effective in reducing cold drafts. “There are now techniques to do this with minimal disruption.” One in five homes in the UK were built pre-1919, and if you live in one of these you must make sure the material is “breathable”, such as wood fibre (pavatex.com/en/home/), to avoid condensation and damp that can rot joists. For information on how to insulate older homes, contact the free helpline run by the Society for the Protection of Ancient Buildings (020 7456 0916, spab.org.uk).

Get better ventilation Cost: £2,000

Hand in hand with insulation should go ventilation. “When insulating a home, it becomes more airtight – but it’s not just the heat that is prevented from escaping. Volatile Organic Compounds (VOCS), allergens, bacteria and viruses are also trapped indoors, as well as moisture which can cause condensation and mould,” says Richard Paine, product director at Vent-axia (ventaxia.com). Indoor air pollution has been linked to a wide range of health problems from allergies, asthma and lung cancer to heart disease.

Now that more of us will be working from home, a good ventilation system – costing around £2,000 to install – could even make us more productive. “Studies of well-ventilated offices show higher productivity and better health among workers,” says de Selincourt.

Draught-proof your windows Cost: £500-plus per window

If you live in a small- to medium-sized house, replacing your windows will likely take up the entire £5,000 of vouchers. Good quality, timber-framed triple-glazed windows – such as those supplied by the Green Building Store (greenbuildingstore.co.uk) – cost about £430 per square metre ( just over 10sqft), so replacing 10 to 15 windows will max out your allowance. Triple glazing – which is around 30 per cent more insulating than standard double glazing – adds about 15 per cent to a window cost but will dramatically reduce drafts. It is possible to use plastic frames and double glazing, for around £270 per square metre.

Replacing windows is an expensive way of achieving only marginal savings as glass loses heat faster than walls. “Seals on double glazing units have a high failure rate,” says Douglas Kent, research director at SPAB. “Getting older windows refurbished and then installing secondary glazing can bring energy savings at far less a cost.”

Think about low-tech solutions for your windows, such as heavy curtains or insulated blinds. With overheating becoming an increasing problem as summers get hotter, external roller shutters – the kind that are common throughout southern Europe – could be the answer, as they help keep heat in during the winter and the sun off your windows in the summer.

Consider a state-of-the-art boiler Cost: £8,000

While replacing an old gas boiler with a new, condensing one (average £2,500) may seem like an easy win, you may be investing in a soon-to-be obsolete product. In February, the Government revealed it was considering a ban on gas boilers to ensure the UK meets its carbon neutral target by 2050. Rosenow says: “We are moving away from all forms of fossil fuel, including gas, and instead heating homes through heat pumps, often powered by renewable electricity.”

Air source heat pumps operate like air conditioning systems in reverse, supplying warm air for indoor use. Heat pumps cost upwards of £8,000 to install, but householders may then also qualify for payments under the Government’s Domestic Renewable Heat Incentive, and receive payments for the first seven years of operation.