Spara och bevara* bibliographic database

Baker, Paul (2008) Technical Paper 1: Thermal performance of traditional windows. Technical Report. Historic Scotland, Technical Conservation Group.

Full text not available from this repository.
Official URL:


The Scottish Government has set a target of reducing Scotland’s carbon emissions by 80% by the year 2050. This is an ambitious target that requires a series of energy saving measured to be implemented across the country. Just under one fifth of Scotland’s dwellings are traditionally constructed, and have significant value to Scotland’s built heritage. The key issues for these buildings is how to make them energy efficient, in a way that does not detract from their character or damage the building fabric. To tackle this question, Historic Scotland’s Technical Conservation Group commissioned the Centre for Research on Indoor Climate & Health at Glasgow Caledonian University to carry out a series of tests on traditional window performance. Windows are the most targeted building element for replacement to reduce heat loss in dwellings. The window that was tested, provided by Historic Scotland, was a typical timber single paned sash and casement window. The thermal performance of the window was tested at the National Physical Laboratory using a guarded hot box system, in order to get an industry-standard measurement of the window’s properties. The thermal transmittance of the window (known as the U value) was measured as being 4.5 W/m2K. Draught proofing is a common practice to prevent wind from blowing in through traditional windows. The test window was draught proofed, and although the U value of the window was not improved, the airtightness of the window was improved considerably, reducing the air leakage by 86%. The window is tighter than the recommended 4,000 mm2 trickle vent for domestic new build. A series of heat loss reduction measures were tested. These measures are all standard steps that people can take and are widely available, including the use of curtains, shutters, blinds, and secondary glazing. All the options were tested on the window in the Environmental Chamber at Glasgow Caledonian University, and all were shown to reduce the heat loss through the glazing to varying degrees. Secondary glazing was the most effective overall option, as it reduced heat loss through the window by 63%. Timber shutters are the most effective option of the traditional methods, reducing heat loss by 51%; curtains reduced heat loss by 14%; a Victorian roller blind reduced heat loss by 28%; a modern roller blind reduced heat loss by 22%. The greatest reductions in heat loss came from combining these measures (i.e. blinds, shutters and curtains all closed) and by adding extra insulation to these options. Using secondary glazing, or combinations of blind and shutters, reduced the U value of the window to below 2 W/m2K, which is the maximum U value allowed by Scottish Building Standards for timber or uPVC windows in new dwellings with an energy efficient boiler. The comfort of a room is affected by the temperature of the surface of the window area. When the surface temperature of the window area is higher, thermal comfort is improved. All the options tested offer improved thermal comfort compared with single glazing alone. This report clearly demonstrates the effectiveness of various options for reducing heat loss through windows. Clearly there are some other considerations to take in to account; for instance, some measures cut out light altogether, and so can only be used at night. Some measures are more expensive than others, which is another major consideration for homeowners. This report allows people to make measured judgements regarding how they can reduce Scotland’s carbon emissions, and their fuel bills, without taking away the character of traditional buildings.

Item Type: Monograph (Technical Report)
Uncontrolled Keywords: Window, U-value, Thermal performance, improvement of windows, Heat loss reduction
Subjects: English > Building Envelope > Windows and Doors
?? build ??
?? monitor ??
Depositing User: Anna Samuelsson
Date Deposited: 12 Mar 2012 12:45
Last Modified: 04 Apr 2017 09:05

Actions (login required)

View Item View Item