The head of Britain's climate change watchdog predicted today that households will need to spend up to £15,000 on a full energy efficiency makeover if the government is to meet its ambitious targets for cutting carbon emissions.

Warning that Britain needs to step up its efforts to reduce greenhouse gases after picking all the "low-hanging fruit", Adair Turner said radical steps would be needed for electricity generation, cars and homes.

Amid growing concern that next month's Copenhagen climate change summit could end in bitter failure, the chairman of the government's climate change commission warned against using the drop in emissions caused by the longest recession since the 1930s as an excuse to relax in the fight against climate change.

The government has pledged to cut carbon emissions by 34% from their 1990 levels by 2020 but slipped off course during the economic boom earlier this decade. "When we get the figures for 2008-09 we may look to be on target, but only because we have had a thumping recession," Lord Turner said.

"There is a danger of the government saying "look, we are back on target". We will be back on target for the worst possible reason."

Turner said that the UK had made "pretty rapid progress" on cutting emissions during the "dash for gas" in the 1990s, but had not maintained the progress during this decade. Tough decisions were now needed because there were limits to improvements to the internal combustion engine and Britain was running out of "easy things" to do in the home.

"After home insulation and more efficient boilers, we now need more intrusive things - double glazing, cavity wall insulation, solid wall insulation."

He added: "We need much more of a whole house approach - one-stop shops where people can get a total report on what they need to do to their homes. It may be expensive - between £10,000 and £15,000."

The CCC believes that the cost of the scheme would be paid for by a combination of government subsidy and higher electricity bills.

Turner said there was a case for greater state intervention in helping to reduce carbon emissions from the motor industry. Arguing that there were "limits" to what markets could achieve, the CCC chairman said: "We need support for the initial wave of electric cars."

The government has allocated £250m to hasten the arrival of electric cars but Turner said the CCC would like to see £800m of public money spent on setting up a network of charging points. "It's chicken and egg. Motorists won't buy the cars unless there are enough charging points; the government is reluctant to put in the charging points while there are no electric cars."

Ministers have accepted the CCC's recommendation that carbon emissions should be reduced by 80% from their 1990 levels by 2050, and the first three carbon budgets covering the period up to the early 2020s were made legally binding earlier this year. Turner said his organisation was now working on a tough fourth budget.

"The 2020s will have to see the radical decarbonisation of electricity, " he said. "That means more renewables, a significant expansion of nuclear or carbon capture and storage plants."

He warned ministers that they would need to contemplate curbs on the expansion of air travel unless there was a way of increasing the supply of biofuels without affecting the ability of countries to feed growing populations. The government has pledged that emissions from aviation will not be above 2005 levels in 2050 and the CCC will provide a range of options for aviation in a report next month.

Turner said experts should look at the possibility of using a financial services transaction tax to help poor countries develop low-carbon growth strategies. "Any tax would have to be agreed at the global level because it would be difficult to enforce in one country. That's why people have tended to think that the proceeds should be used for global common goods, such as the environment."

Power stations that do not have carbon capture and storage will be taken out of commission, Turner said.