£50,000 to upgrade the house that heats itself
This couple have gone to extreme lengths to insulate one of their properties – including making it ‘airtight’. Olivia Rudgard reports
Britain’s houses may be among the least energyefficient in Europe, but the latest technology enables newbuild houses to use less energy than ever. Some architects are even creating houses that are designed to cost nothing at all to heat. Homes built to a standard called “Passivhaus” use extreme levels of insulation, recycled heat and “airtightness” to reduce heating bills to almost zero.
It doesn’t come cheap, though, and fewer people are likely to benefit because of the cancellation of government subsidies such as the Green Deal, experts say.
When Pete and Linda Wilkinson from Lancashire decided to refurbish their buy-to-let property, they could have carried out the essential improvements for about £15,000. Instead they decided to go all out and spend £50,000 on making the three-bedroom home one of the most energy-efficient in the country.
This involved new windows and doors, special wall and window insulation, mineral-wool roof insulation and carpet insulation.
Mr Wilkinson, 54, runs an architectural, building and renewable energy business and embarked on the refurbishment to show what could be achieved with a high level of investment.
The couple’s own home has a wood-pellet-fired boiler and solar panels on the roof.
The couple’s rental property needed serious refurbishment anyway. Rewiring, a new kitchen and new windows and doors were all required.
Had these changes been made to conventional standards the cost would have been around £15,000. The high-specification energyefficiency elements added about £36,000 to the bill.
The refurbishment included special insulation in the walls and around the doors and windows, insulation in the roof and tripleglazed windows.
The Wilkinsons also added a new staircase made from redwood certified by the Forest Stewardship Council as sustainable.
A mechanical ventilation system with heat recovery was also installed. This extracts warmth from air filtered from inside the house and transfers it to air being brought into the house from outside. It is designed to reduce the amount of energy needed to keep the house warm.
The total cost for all the work was £51,890. The most expensive element, at £10,539, was installing triple-glazed windows and surrounding insulation.
Installing wall insulation cost £7,141 and painting the house with natural oil paint cost £5,627, including labour.
The £51,890 was split almost evenly between material costs and labour costs.
A full cost breakdown can be seen in the table below.
Mr Wilkinson estimated that the annual gas and electricity bill for the house was just £200.
According to UK Power, a comparison service, the average annual energy bill for a medium-size house is £1,066. This means that the Wilkinsons’ tenants save around £866 a year.
The couple estimated that the efficiency element of the refurbishment cost around £36,000.
As a result, it would take 41 years for the occupants to save enough on energy costs for them to break even
‘In future there will be an increasing market for properties like this’
on the initial outlay. However, Mr Wilkinson said investment on this scale was designed for the long run.
“It’s a long-term strategy so that we can provide a low-energy building for tenants,” he said.
“We should be aiming to reduce people’s costs over the lifetime of the building, not necessarily just for the time that they’ll live there.”
They also hope that the measures will improve the long-term value of the house.
“In the future there will be an increasing market for properties like this because energy isn’t getting cheaper, it’s getting more expensive,” Mr Wilkinson said.
“Just over the past few years it has got disproportionately more expensive to heat your home.”
Adopting the Passivhaus standard used by the Wilkinsons is an extreme
‘ PASSIVHAUS’ MAKEOVER: HOW MUCH DID IT COST?
Work Demolition and stripping out existing fittings Remedial works to existing structure External wall insulation and airtightness Mineral wool insulation, plasterboard and adding plaster coat to partitions Ground floor insulation and bamboo flooring First floor and ceilings: adding mineral wool insulation to partitions £1,600 First floor ceilings: adding airtightness/insulation £2,813 New staircase/ balustrade in sustainable redwood £1,932 Triple-glazed windows/doors, insulated frames £10,539 Plumbing/heating installation inc new combi boiler, pipework and radiators £1,886 New shower and bath £749 Internal and external low-energy light fittings £1,789 Mechanical ventilation with heat recovery system £2,919 Kitchen installation (not including appliances) £3,504 Decorating with natural oil paints £5,627 Total cost £51,890
Cost £3,340 £910 £7,141
Pete and Linda Wilkinson outside their own home and, left, their rental property, which is one of the most energyefficient in the country