With the Green Deal just one week away, the industry is still waiting for answers on how the assessment procedure will work.

The Green Deal scheme will give householders and businesses up to £10,000-worth of energy efficiency improvements to their property for no upfront cost, but industry professionals claim that the radical initiative is threatened with collapse before it is even announced. Companies involved with making the Green Deal possible face uncertainty over how the pricing structure will work for both the industry and the consumer.

Ed Davey responded: "I understand your point, but this is something that the market will want to tackle, and all our evidence from talking to providers is that they won't want to allow any assessment fee to put consumers off. So some might charge a fee - especially if you own a mansion - but for those of us who live in terraced properties, my guess is that many providers will do the assessment for free."

The concern is that if the homeowner or tenant is liable to foot the bill for this, then there is an initial cost to the Green Deal from the offset, which is likely to put potential candidates off and hinder the success of the scheme.

With an upfront cost which could be in excess of £150, customers risk paying for an assessment that could lead to no benefit. It may also transpire that their home does not meet the Golden Rule, intended to ensure that the cost of the improvements do not exceed the current cost of a property's energy bills and the savings that will be made.

Wynter said: “I know I speak on behalf of other members of the industry when I say that I am growing tired with the lack of clarity on the matter. I have asked at meeting after meeting with the Department of Energy & Climate Change and? Green Deal providers, and have met a blank wall, and once again those who are responsible have continued to skirt around the issue.

"It is outrageous that with less than two weeks until the launch of the Green Deal, people like the Energy Secretary are operating on guesswork. They should not be 'guessing' how providers will conduct the assessment process, it's absurd.”