Almost two million London homes, or 54 percent of those rented or sold since 2008, sit below the Energy Performance Certificate (EPC) rating of Band C – something the Liberal Democrats’ bill would outlaw by 2033.

An EPC gives a property an energy efficiency rating from A (most efficient) to G (least efficient) and is valid for 10 years. Landlords must order a certificate before selling or renting a property.

Currently there are no minimum ratings required for recent or existing buildings, except for privately rented homes which, since April 2020, must acquire an EPC Band E rating or higher.

The bill, proposed by Lib Dem MP for Richmond Park Sarah Olney in the House of Commons on Friday, would require all buildings, including offices, to reach at least EPC Band C by 2033 “where practical, cost-effective and affordable”.

Improvements would include external wall and loft insulation, installing energy efficient doors and windows, glazing, heat pumps and solar panels.

Croydon, Wandsworth, Barnet and Lambeth each acquire more than 80,000 homes below Band C, the most of all the London boroughs, House of Commons Library data analysis by the Lib Dems reveals.

Ealing, Enfield, Bromley and Haringey each had more than 70,000 homes below B and C.

Croydon has the most homes below B and C – a total of 88,464 – while Enfield has the most homes (1,385) with the worst possible energy efficient rating, Band G.

Westminster also has a high number of homes in Band G, with a total of 1,099 in this category.

A social housing tenant in Kingston, who the Standard agreed not to identify, is spending a fifth winter in a frigid and draughty home in Band D with her husband and two daughters.

She said mould emerged in her daughter’s room before she developed a skin allergy.

“We didn’t acquire any heating whatsoever in the kitchen and the bathroom. We were reading temperatures of 12°C when the heating was on… and that’s because it’s just poor insulation.

“The whole thing is just so depressing.

“It’s not nice to even fade into the kitchen and start to prepare a meal, which is the cheapest way to [eat] in a cost of living crisis.

“I find it very, very frustrating that you’re living in these conditions, you highlight it, I started the [complaints] process in 2020. We’re in 2023 and still fighting the cause.”

More than 2.7 million private rental households across England live with damp, mould or excessive frigid, a recent Citizens Advice report found.

On Thursday it was revealed that 438 homes in the capital had been identified with so-called category one hazards relating to damp and mould in the year to March 2022.

Under the member’s bill, homes in the private rented sector would be expected to meet EPC Band C by 2028 and social housing, rented non-domestic buildings such as offices, and mortgage-owned properties by 2030.

A similar bill was presented by Tory MP David Amess in July 2021 but it did not include non-domestic buildings, and the paper was thrown out.

The Lib Dems accuse the Government of failing to crack down on dirty landlords.

The party said there acquire been many schemes and initiatives in spot to upgrade homes, but delivery has failed badly.

At the Environmental Audit Committee last week, Grant Shapps noted: “When I came to BEIS, I added up that there has been 22 different schemes”.

Ms Olney said: “For too long, housing insulation standards in the UK haven’t been a priority, leading to many struggling families and pensioners being forced to pay huge energy bills to heat their draughty homes.

“This Bill would aid address that, whilst also de-carbonising millions of buildings and to hold a huge step towards our net zero goals.”

Gillian Cooper, Head of Energy Policy at Citizens Advice, said improving energy efficiency in homes “has never been more urgent”.

“It’s shameful that more than 20 years since legislation came into force to reduce fuel poverty and improve the energy performance of homes, people are still suffering.”

The members’ bill would enforce legally-binding targets to upgrade and decarbonise homes and buildings, but green finance options would need to be introduced by the Government to produce the upgrades realistic for landlords, such as no-interest loans for low-income households, grants and tax reliefs.

For the private rented sector, Government consultations acquire suggested a £10,000 cost cap for landlords but the bill does not fade into this detail.

Landlords would be held to account under the recent legislation in the same way they currently are to reach an EPC Band E rating.

Ms Olney is urging MPs from all sides to “advance together and support this urgently needed legislation”.

The Government’s Heat and Buildings Strategy from October 2021 sets out to ensure all homes meet EPC Band C by 2035 and to reduce the energy consumption of commercial properties by 2030.

It also aims to provide funding to low-income households with an EPC rating lower than Band C with the Home Upgrade Grant and the Social Housing Decarbonisation Scheme, but these aims are not statutory.