PLANS for the "most efficient building in the UK" have been turned down by Craven District Council.

The owners of Fairfield, in Burton-in-Lonsdale, applied to build a four-bedroom extension complete with lounge, study, workshop, office and cellar in order to give them more space to foster disabled children.

The extension would have been made from a prefabricated timber system in order to achieve "super-insulation" standards and minimise the energy needed to heat it. The timber frame would also be relatively lightweight.

In order to achieve greater energy efficiency the windows would have comprised linked double and single glazed casements, which would be much deeper than regular windows. The windows would stand proud of the walls and be housed in coloured softwood cladding panels to maintain the energy efficiency of the walling system.

Burton-in-Lonsdale Parish Council was concerned over the use of the property as there had been some confusion. The planning officer stated that there had been a mistake in the neighbour notification letters and site notice which said "change of use" when it should have read "extension".

Two neighbours objected, raising concerns over the workshop element of the proposal and the size of the extension.

The proposed materials had been chosen to achieve minimal environmental impact and would have been sourced locally where possible.

Rod Hughes, agent for the applicants, said: "This building will be the most efficient in the UK if built."

He added that the extension would not be visible from the street as it was set amongst trees.

Mr Hughes acknowledged that the extension was large but said it was appropriate for the family's needs.

Councillor John Sayer recommended the plans for refusal. He said: "The house in question has no particular architectural merit but to add on to it what I consider an incongruous feature is not going to help it."