A poor energy rating could cost new homeowners as a new green tax is being considered by the government.

This new tax could add 850 pounds to the cost of buying a home. It could possibly require the new owner to spend at least 15,000 pounds in improvements.

A 0.5 per cent stamp duty is being considered by the coalition but commissioned by the last Labour government. This would be in addition to the normal stamp duty. By sharply improving the rating within a year, its possible to reclaim twice the amount of the green tax from a Green Investment Bank.

The property industry considers the tax unworkable and fear it will throw the housing market into turmoil.

There is already an energy rating system in place upon inspection. Ratings are from "A" to "G" and each provides tips on how to improve the home’s rating. The green tax would apply to homes with F and G ratings.

Improvements to the home for a better energy rating would be excellent use of a remortgage. Because "green" is such a prolific description in construction as well as several other industries, funding through remortgage should be a great possibility if other stipulations are met.

Many housing experts though feel that any extra expense heaped on buyers would damage the market.

Also, Nicholas Leeming of sales website Zoopla.co.uk says: "Some 65 per cent of UK homes were built before 1965, and in London 27 per cent before the first world war. This would clearly be unworkable."

The firm PRP recently retrofitted a 1940's three bedroom house. The process took too long and was too costly.

This being discovered, the two government departments considering this move say this is one of many ideas being considered.