RISING fuel costs and environmental concerns have forced councillors to consider lifting a ban on double glazed windows in Edinburgh's most historic buildings.
Hundreds of residents in and around the New Town are currently prevented from replacing their draughty old windows, because of fears that double glazing would change the appearance of their properties.
But officials have now admitted their stance on category A and B-listed buildings "seems to conflict" with the push to reduce carbon dioxide emissions and cut household energy bills.
The council is set to trial different examples of double glazing, with the results used to determine its future planning rules.
A recent study of nine B-listed Georgian tenement flats in the city found that other non-invasive energy saving measures – such as draught proofing – can reduce annual energy costs by up to 400.
The double glazing trial is likely to be carried out in these same buildings on Lauriston Place.
Alistair Cant, director of the Lister Housing Co-operative which owns the properties, said: "These are fantastic buildings, but they are not so good in terms of energy efficiency. They have high ceilings along with single glazed timber sash windows, which are very draughty.
"Draughtproofing can help a lot, but double glazing improves the temperature surface of the glass, and if the ban is reviewed it could help people have a better choice of options."
When planning applications are submitted to the council, thermal insulation is often included as the main reason why property owners want to alter or replace traditional sash and case windows.
The council's director of city development, Dave Anderson, admitted the authority's restrictions are a "particular issue" in Edinburgh, where 75 per cent of buildings in the World Heritage Site are listed.
"Technology is changing and new materials in certain circumstances can work well in older buildings," he said.
"In order to fully consider the implications of the use of double glazing in category A and B-listed buildings, it is recommended that a trial is arranged using a range of types of sealed-unit double glazing, and other thermal efficiency measures, to allow for discussion of their potential use with Historic Scotland."
But a spokeswoman for Historic Scotland was less positive about the proposed trial.
She said: "Though often perceived as the solution to heat loss, double glazing is not the only way to mitigate heat loss, and more economic non-invasive steps can have a good impact, without altering the original fabric of the building."
She added: "As with any work to a listed building, we would consider applications for the replacement of windows on their individual merits.
"Since traditional buildings, both listed and unlisted often vary little, it may be preferable to undertake the trial in an unlisted building, or utilise examples where such units have already been installed."