In 2009/2010 Changeworks, a sustainable development organisation, led a project in Edinburgh, in which single-glazing products and their thermal performance was measured in situ by Glasgow Caledonian University. The project was funded by the City of Edinburgh Council and Historic Scotland and supported by the Edinburgh World Heritage Trust and Lister Housing CoOperative. The project results showed that replacing single-glazed with slim profile double glazing can significantly improve the thermal performance of historic timber windows, whilst retaining their joinery work. The project’s findings, published in a project report for the City Council and in Historic Scotland Technical Paper 9, led to a change in Edinburgh’s planning guidelines for listed buildings in 2012, which now allow for the installation of slim-profile double-glazing in listed buildings.
In 2011/12 after the new glazing was in situ for two years it was decided to re-measure thermal performance of the replacement units and compared these results with the results of the initial project. The results are detailed in Technical Paper 20 and a comparison of the results is also featured in the Table below