Householders across the UK are to be offered an additional £100 million to fund energy-saving home improvements, after a government scheme proved so popular it ran out of cash within three months.

Energy Secretary Ed Davey was announcing the new money for the Green Deal home improvement fund at the Liberal Democrat conference in Glasgow.

He was also due to hail progress on making it easier for consumers to cut their bills by switching energy suppliers, and set a target - described by aides as "ambitious" - for smaller independent firms to take 30 per cent of the market from the so-called "Big Six" by 2020.

And he confirmed Lib Dem plans, set out in last month's pre-manifesto, to offer households a £100-a-year government-funded council tax discount over the next 10 years if they improve their energy efficiency.

Applications for the first tranche of grants under the £450 million Green Deal - intended to help fund items like wall insulation, double-glazing and new boilers - opened in May, but the first year's money was all scooped up by the end of July, leaving a gap of several months before would-be home improvers could make fresh bids.

Aides said the new cash would help fill that gap and would remain on offer until it has all been spent.

"We've delivered, not by tweaking the same old business-as-usual models we inherited from Labour, not by doing what our Tory Coalition colleagues wanted or what the big energy companies or Whitehall wanted us to do," Mr Davey was expected to say.

"We're succeeding because we are outsiders, without vested interests. To begin the big shift from fossil fuels. To take on the Big Six energy firms Labour left Britain with. To win in Europe and the UN for ambitious climate change.

"That's why I can announce today that I am delivering on my promise to halve switching times this year. Every major energy firm is on schedule to deliver the faster switching I have demanded," he added.