And £1bn will go towards the decarbonisation of schools and hospitals – many of which are squandering heat.

Homeowners will get vouchers of up to £5,000 to make energy-saving improvements to their properties.

Chancellor Rishi Sunak is due to announce the pledge in a major speech tomorrow on the government’s plan to steer the country through its coronavirus recovery.

It will cost £2bn and comes in addition to a further £1bn to be spent on the decarbonisation of public buildings such as schools and hospitals – many of which are squandering heat and contributing towards climate change.

In his economic update to parliament on Wednesday, Mr Sunak is also expected to unveil a £50m pilot project to retrofit social housing through measures such as heat pumps.

But campaigners said that alone won’t be enough if Britain is to reach its goal of being carbon neutral by 2050.

The voucher scheme will see the government cover the costs of at least two-thirds of the price of home improvements to save energy.

Online applications will go live in September – with the voucher issued once an accredited supplier has provided a quote and the work is approved.

Britain’s building controls for energy consumption are among the worst in Europe – yet existing buildings have been highlighted as creating the biggest energy emissions headache.

Sky News spoke to a science teacher at a school in Manchester who revealed students concerned about climate change have taken it into their own hands to make their school more energy efficient.

Parrs Wood School in Manchester was originally built in 1965.

Chris Baker said that, over the course of eight years, students have overseen a number of significant improvement projects and have secured more than £600,000 in retrofitting grants.

Three years ago, when solar panels were fitted on the roof, it was the biggest collection of solar panels to be installed at a school in the UK.

There have been lots of other projects, including adapting lighting.

Overall the school has reduced its electricity bill by a third.

Mr Baker said: “You’ve got a lot of students doing climate change protests and here you’ve got an opportunity for students to get involved in the process and not just raise awareness.

“The students are amazing. We’ve done it over eight years as an educational project. We’re now trying to teach other schools how to do it.”

It is these kinds of improvements which the government will need to support if leaky public buildings aren’t going to hinder Britain’s net zero goal.

Luke Murphy, of the Institute for Public Policy Research, said: “We know that buildings make up a significant contribution to our carbon emissions and therefore the investment announced in terms of a public buildings decarbonisation programme – but also the money they’ve announced for social housing – is really welcome.

“The key will be if this is a downpayment on a wider long-term programme over the next 10 years or whether this is a one-off stimulus.

“If it’s the latter then that’s not enough.”