As a result of the project, the council is likely to update its planning policy for windows in listed buildings. Pilkington energiKare™ Legacy provides similar energy efficiency performance to standard replacement low-e double glazing but in a much thinner profile.
Prior to the refurbishment, Changeworks measured the U value of the listed buildings’ single-glazed windows at 5.5; with the innovative Pilkington energiKare™ Legacy glazing system, the U-value has been improved significantly, to 1.4. The result is excellent thermal performance from a unit fractionally as thick as a standard IGU.
Nicholas Heath, Project Development Officer at Changeworks said, “Lister Housing Co-operative is keen to save its tenants energy and money off their fuel bills while conserving the original look of the properties; this was a challenge Changeworks was keen to take on. Pilkington energiKare™ Legacy was one of a number of slim-profile double-glazing systems we installed in high-profile listed buildings in Edinburgh’s historic centre. We worked closely with the City of Edinburgh Council, Historic Scotland and Edinburgh World Heritage to ensure that the 60 panes of Pilkington energiKare™ Legacy installed did not damage the timber frames, for example. We also carried out in-situ thermal efficiency measurements of all systems installed, and the Pilkington energiKare™ Legacy system achieved the lowest U value.”
Pilkington energiKare™ Legacy utilises two panes of glass separated by a gap of 0.2mm (compared to a typical 16mm gap in traditional double glazing). The glazing’s overall thickness of 6mm is enough to provide an aesthetically pleasing glazing solution where a slim profile is needed and a thermally efficient window. Moving to glazing with a low U value whilst keeping high solar transmission from single glazing can save over £300 per year on heating costs, and around 32 tonnes of CO2 over the lifetime of the window, in a typical 3 bed semi detached property.
Andy McDowell, Pilkington said, “The key criteria for this project was that the buildings achieved a minimum U-value, retained their original look and provided an example to other historic buildings across the UK as to how to refurbish properties in a way that is compliant with conservation principles. Pilkington energiKare™ Legacy is designed specifically for heritage projects; clients can choose to either retain the original frames or replace with replica, slim line frames.”
Pilkington energiKare™ Legacy utilises advanced Pilkington Spacia™ technology.
This consists of an outer pane of low-emissivity glass and an inner pane of clear float, with a vacuum rather than air or another gas in between.
A detailed project report will be available from Changeworks in May 2010, which includes details of all systems trialled together with the results of U-value and embodied energy monitoring.