Green Deal Finance Company has seen growth in applications for home improvement finance plans increase five-fold in the past 12 months.

The Green Deal energy efficiency scheme now has over £50m worth of finance in place to fund household energy efficiency improvements across the country, new figures reveal.

Over £21m of applications have been received by the Green Deal Finance Company (GDFC) in the past six months, while since May last year plan sales have increased five-fold, which suggests that after a slow start the government's flagship programme is building momentum.

The GDFC hailed its 'best ever' week in April, which saw over £2.25m of applications for fitting measures such as insulation or green energy generation systems, while weekly applications since Easter have consistently exceeded £1.8m.

Over 550 households now make applications for Green Deal finance each week, taking total plans in the system to over 14,000 with an average plan size of £3,500.

More than £30m has so far been lent by the company through the pay-as-you-save home energy efficiency scheme and over £20m worth of applications are now moving through GDFC systems. Solar PV plans show strong growth and now form a third of plans and applications, the company said.

Installers are also benefitting - the GDFC said it has allocated over £72m in lines of trading credit to Green Deal Providers, with over 60 firms now accredited.

The figures show a marked improvement for the much-criticised Green Deal scheme, which after kicking off in 2013 fell well short of its initial target of signing up 10,000 households in its first year of operation.

The slow start was blamed on IT glitches and low numbers of providers, while further problems emerged late last year when the GDFC was forced to source additional funding from the government to head off the threat of liquidation.

However, in the past year the market has picked up, with the GDFC passing the 10,000 plan milestone earlier this year and hitting 12,900 in April.

Mark Bayley, GDFC chief executive, praised the "strong growth" shown by the programme.

"£50m worth of plans and applications is a major milestone when you remember it's barely two years since the first Green Deal plan was signed," he added. "The step-change in the growth of the GDFC is an example of the potential power of pay-as-you-save and the considerable effort of our small and medium-sized provider network."

The scheme is likely to prove crucial to the new government's energy efficiency strategy, after the Conservatives pledged to deliver energy efficiency upgrades to one million households over the course of the parliament.

However, green campaigners have argued the government's plans represent a significant slowdown in the level of energy efficiency upgrades compared to the last parliament. Moreover, industry insiders are now warning that while the Green Deal scheme is enjoying some growth there are concerns the accompanying Energy Company Obligation (ECO) scheme is facing a slowdown as energy firms look set to meet targets for upgrades well ahead of their 2017 deadline.