The Green Deal Finance Company has doubled its membership since it was started in March, with the addition of 21 more companies joining.

The industry-led consortium brings together firms which hope to finance energy efficiency measures in UK households.

One of the group’s members, PricewaterhouseCoopers estimate more than 15 million UK homes are not properly insulated, wasting money and energy.

Paul Davies, from PriceWaterhouseCoopers said: “We expect membership to increase again over the coming months as organisations prepare to take advantage of the consumer interest in this scheme at its roll out in Autumn.”

The Green Deal was introduced in the Energy Act 2011 to allow private firms to offer UK consumers energy efficient improvements to their buildings. Consumers will pay back the cost of improvements over a period of time through repayment charges added to their energy bills.