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Thermal assessment of internal shutters and window film applied to traditional single glazed sash and case windows

Currie, John; Bros Williamson, Julio; Stinson, Jon; Jonnard, Marie


Julio Bros Williamson

Marie Jonnard


This report describes the work conducted by the Scottish Energy Centre (SEC) at Edinburgh Napier University for the National Trust of Scotland, measuring the thermal transmittance (U-value), for two types of glazing insulation: shutters and film. The objective was to determine the thermal insulation benefit of these measures when applied to an existing single glazed sash and case window. The building selected for the study is a detached 18th century cottage, Wee Causeway, located in Culross. It is a dwelling of traditional construction (solid stone wall) where some energy efficiency refurbishment works were completed in 2012 (wall and ceiling insulation). In the summer of 2013, glazing film, designed to improve thermal performance, was installed on all rear windows of the building, except the bathroom window. The textured translucent glass of the bathroom window proved unsuitable for the application of the glazing film. Thermally insulated timber shutters were applied to the interior side of the front facing window openings. The heat transfer through the bathroom glass and a front window pane was subsequently measured to provide a reference benchmark, to compare with the improved windows. This report also analyses the effectiveness of improvements for upgrading traditional buildings, combining 2012 wall monitoring (Currie et al., 2013) and 2014 window testing. Using SAP software, the report presents several modelled thermal scenarios, which demonstrate the effectiveness of each intervention if applied in isolation. Each modelled scenario is presented in terms of energy efficiency rating (SAP), environmental impact score, and space heating requirements. The report concludes by combining the most thermally efficient materials for each element into one 'best case' model. In Section 2, the methodology which was used for the testing of U-values in-situ is explained. The two methods of improving U-values for the windows are detailed in Section 3. Section 4 develops the results monitored in Wee Causeway and presents the findings of IR thermography and airtightness tests. Section 5 provides a review of the wall and ceiling thermal measurements completed in 2013. Finally Sections 6 and 7 present comparative tables detailing retrofitting techniques, and thermal performance indicators for the solutions trialled at Wee Causeway.


Currie, J., Bros Williamson, J., Stinson, J., & Jonnard, M. (2014). Thermal assessment of internal shutters and window film applied to traditional single glazed sash and case windows. Scotland: National Trust of Scotland, Historic Scotland

Report Type Technical Report
Publication Date 2014
Deposit Date Oct 13, 2014
Peer Reviewed Not Peer Reviewed
ISBN 9781849171748
Keywords built heritage; old buildings; historic houses; traditional architecture; windows; glass; energy efficiency; energy conservation measures; insulation measures; thermal insulation; stone walls; testing; monitoring; Scotland; UK
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