It’s the £330bn question that will affect every homeowner and buyer – but it is being ignored by the Government.

For more than a year, ministers have been avoiding the issue of the incoming Energy Performance Certificate rules. This seemingly innocuous issue will have a huge impact on the housing market – far more than anyone realises, including ministers.

Their plans will force property owners to shell out thousands of pounds simply to be able to sell up or rent out their home. If they don’t make the eco upgrades, it could render their properties unmortgageable or slash their house price. All this while the biggest cost of living crisis in a generation squeezes incomes to breaking point.

Landlords are the first target. They have been told they must bring their properties up to Band C by 2025 for new leases and by 2028 for existing lets. Around two million landlords will be stung, according to JMW Solicitors, and they will face a total bill of £10bn.

But this is a wider issue: under current plans, lenders will be required to have an average Band C rating for their portfolios by 2030. People with inefficient homes will pay higher mortgage rates and will find it harder to remortgage. The rules will force 15 million homeowners to each spend thousands of pounds on home improvements, according to Halifax, as around 60pc of all homes in England and Wales currently have an EPC rating below C. Estate agency Savills has put the bill for bringing every property in Britain up to standard at £330bn. The scale of the upgrade programme is so great that there won’t be enough people to carry out the work.

There remain so many unanswered questions. There could be a £10,000 limit on spending per property, but we don’t know for sure. The Government may offer grants but has not announced anything yet. There may be exemptions for certain types of property, but this is not confirmed. All landlords know is that they face an eco red tape nightmare in a few years’ time. How can they make upgrades – at the cost of thousands of pounds – and follow the rules if those rules haven’t been set out properly?

The Government is also ignoring the other elephant in the room: it has admitted that its EPC system is not fit for purpose, but appears to be forcing people to comply with it regardless. It was designed to reward the use of gas over electricity, but times have changed and the system has not kept up. The upshot is that it penalises people who install heat pumps (which run on electricity) – the very same costly devices ministers are pushing on British homeowners.

We shouldn’t be surprised. Every new eco upgrade policy announced has crashed and burned. The Green Homes Grant was abruptly stopped before it could get going. The new boiler upgrade scheme, which offers money so homeowners can buy heat pumps, is limited to helping just 90,000 homes and covers less than half the cost of installation. The Chancellor cut VAT on eco upgrades in the Spring Statement, but costs have risen so much it will barely make a dent.

The Government ended its consultation at the beginning of last year, yet we are still waiting for answers.

You can contact Isabelle at isabelle.fraser@telegraph.co.uk