The UK government’s decision to allow homes to be built to low standards of energy efficiency cost owners of newly built homes about £234m last year, analysis shows. The zero carbon homes standard was supposed to come into force in 2016, but the measure, which was introduced under Labour, was scrapped by the Conservative government in 2015. Since 2016, almost 1.2m new homes have been built with energy efficiency standards that are well below those needed in the long term to reach the net zero greenhouse gas emissions target. The Liberal Democrats have calculated that as each home under the zero carbon standard could have expected an energy bill saving of £200 a year, the cumulative cost to households living in newly built homes has been about £790m since 2016. The research follows separate findings from Labour last year that suggested owners of newly built homes would face bills of £20,000 to upgrade them to zero carbon standards, a cost of about £20bn for the whole of the UK. If housebuilders had been forced to meet the zero carbon homes standard, the cost would have been about £5bn, and borne by the lucrative homebuilding industry. The technology needed to build zero carbon homes is already widely available, and in widespread use in other countries. It comprises heat pumps, solar panels, high-grade materials such as thermal glazing, and high-standard insulation. But these technologies are not widely used in the UK for building new homes, as they are more costly than the current building regulations require. Homebuilders have been reluctant to build to such requirements, because although it would mean large savings over many years to the owners of the dwellings, using the necessary materials and techniques would add to their construction costs. Wera Hobhouse, the energy and climate change spokesperson for the Liberal Democrats, said: “The Conservatives have slapped hundreds of pounds on to people’s heating bills by scrapping energy efficiency standards for new homes. This shameful record has left over 1.2 million more people living in poorly insulated homes, making them even more vulnerable to soaring energy prices. “It shows the Conservatives are more interested in cosying up to their property developer friends than slashing people’s bills and tackling the climate crisis.” Green campaigners and analysts fear the government is planning further cuts to the UK’s spending on insulation and other energy efficiency measures. The Energy Company Obligation, which adds about £1bn a year to energy bills to pay for insulation and energy efficiency measures for the poorest households, is under threat from the Treasury, although it has saved an estimated £11.7bn on bills for people on low incomes. Hobhouse added: “The fact ministers are now considering cutting even more energy efficiency measures shows that they still haven’t learned any lessons from this failure. The government needs to urgently bring back energy efficiency standards for new builds and insulate older homes, so people aren’t condemned to years of eye-watering energy bills.” A government spokesperson said: “Record global gas prices only underscore the importance of our plan to generate more clean power in this country so we can reduce our reliance on expensive, volatile fossil fuels. As such, we have no plans to move away from our green ambitions, and we remain committed to supporting our homegrown renewables sector, investing over £6.6bn to decarbonise homes and buildings across England, and extending the Energy Company Obligation from 2022 to 2026, boosting its value to £1bn a year.” The Conservatives have received an estimated £18m from property developers since Boris Johnson became prime minister.