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Pilkington energiKare™ Legacy transforms homes in Edinburgh

26 January 2011

Improving the energy efficiency of ancestral buildings is a challenge that window fabricators and installers are continuously looking for ways to answer. With regard to government legislation to reduce CO2 emissions, expert in this field, Changeworks Resources for Life, based in Edinburgh, has carried out a number of high-profile, award-winning demonstration projects trialling innovative energy-saving solutions in traditional properties. Its latest refurbishment uses slim, low-e Pilkington energiKare™ Legacy in a category B listed Georgian tenement flat in an attempt to influence the controlling authorities and highlight the potential for improving the poor energy efficiency of heritage properties up and down the UK.


Changeworks specified and installed Pilkington energiKare™ Legacy in nine occupied flats in Archibald Place, a social housing refurbishment in Edinburgh. Pilkington energiKare™ Legacy provides similar energy efficiency performance to standard replacement low-e double glazing but in a much thinner profile. It was designed with for heritage projects in mind, and offers the choice of installation with the original property frames or with replacement replica, slim line frames.

Prior to the refurbishment, the listed buildings’ glass had a U-value of approximately 5.5 W/m2 K. Thanks to 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 insulating glass unit and seamless integration of new glazing into original timber frames.

Archibald Place is no standard refurbishment. In a previous project, Changeworks requested permission to install slim-profile double glazing into historic properties but was refused due to Council building controls. Negotiations with the Council following this difficulty led to the funding of Changeworks to refurbish Archibald Place; a pilot project, installing a range of slim-profile systems into the nine occupied flats in an entire Georgian grade ‘B’ listed tenement block building (owned by Lister Housing Co-operative) in central Edinburgh. This was a United Nations Educational, Scientific and Cultural Organisation (UNESCO) World Heritage Site and conservation area where approximately 75 per cent of the buildings are listed. The UK National Commission for UNESCO (UKNC), the UK Government and UNESCO are committed to working together towards identifying, protecting and conserving these places for the benefit of future generations. Changeworks hopes that following the project and subsequent analysis, the Council will update its policy and allow such discreet systems in more listed buildings in Edinburgh in line with UNESCO policy. This could also be replicated across the UK.

Nicholas Heath, Project Development Officer, Changeworks said, “Lister Housing Co-operative had a requirement to save its tenants energy and therefore reduce their fuel bills, while conserving the original look of the properties. It challenged Changeworks to find a solution for all nine flats. The listed status of the properties meant it was important we preserved the timber sash windows. 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 properties or their original frames. Changeworks will be writing a comprehensive project report which will be submitted to Edinburgh Council in Spring 2010.”

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 thickness of just over 6mm is enough to allow 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 the benefit of high solar transmission away from single glazing can save a substantial amount of energy and carbon whilst making the rooms far more comfortable to live in.

The importance of this project to Changeworks and the legislation around heritage properties is further amplified by the fact that additional funding has been secured from Historic Scotland to carry out in-situ U-value monitoring and embodied energy analysis of all systems installed. This data will be used as a case study for other government bodies in the UK highlighting the value and simplicity of replacing inefficient windows in listed buildings. As well as a tool to lobby government, this study will also provide an informative dissection of the project that window fabricators and installers can use for reference in other heritage projects.

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.