Insulation installed in the last decade will save Britons nearly £1.2 billion a year, analysis suggests amid calls for more energy-saving efforts as prices soar.

The Energy and Climate Intelligence Unit (ECIU) assessment that found six million homes had been upgraded to energy performance certificate band C from 2009 to 2019 with measures such as loft and cavity wall insulation.

Upgrading a home from band D to band C cuts gas demand by 20% per home, which will save homes £194 per year from April 2022 – and more if energy bills climb further as expected in the face of rising high gas prices due to reduced supply, increased demand and war in Ukraine.

The energy efficiency measures installed in the decade to 2019 will save bill-payers an estimated £1.15 billion this year, the organisation said.

As debate rages on how to tackle surging energy bills, green campaigners and anti-fuel poverty charities have called on the Government to increase efforts to improve the energy efficiency of the UK’s draughty, heat-leaking homes to cut fuel demand and costs for households.

The Conservatives have also come in for criticism for cutting back on green schemes such as the energy company obligation (ECO) under the coalition government in 2013, with a significant drop in insulation rates since then.

Jess Ralston, analyst at the ECIU, said: “Insulation schemes like ECO work.

“They cut the energy being wasted from leaky roofs and walls, cut the amount of gas we need to keep warm and so bring down bills, and they do all that permanently.

“Why are we not talking about this more? If we want to increase security of supply and reduce bills at the same time, the only answer is to use less gas.

“That means insulation. It’s really not that hard to grasp.”

A Government spokesperson said: “Improving the energy efficiency of our homes is the best long-term method to keep household energy costs down and to tackle fuel poverty, which is why the Government is investing over £6.6 billion to decarbonise homes and buildings.

“We’re helping households reduce energy bills through a range of schemes, such as extending the Energy Company Obligation to 2026, helping an extra 305,000 families save an average of around £300 a year. We are also insulating millions of consumers from high gas prices through the energy price cap.”