General Ideas

Glasgow Caledonian University carried out a study (Improving The Thermal Performance of Traditional Windows) on the effectiveness of a range of methods to reduce heat loss through single glazed sash windows. This type of window being common in Scotland and of significance in the work to improve the energy efficiency of the scottish housing stock.

Whilst the project house featured in this web site doesn't have sash windows the results are still important. The report highlights the range of options available to any windows, their relative effectiveness and magnitude of savings. The results are summarised in the table below. The U Value of the original single glazed window was 4.5W/m2K

   Improvement (%)
 Secondary Glazing  63
 Timber Shutters  51
 Victorian roller blind  28
 Modern roller blind  22
 Curtains  14

These are some general ideas for reducing heat loss through or around windows.

Shutters  Very effective and a great range of products are available. A search for shutters reveals the large range of products available. The image on the left is taken from the Purelyshutters web site. Although the shutters used in the report were of the solid wooden variety the more modern types available will still offer substantial savings.  
Thermal Curtains  Thermal Blind Available in a range of fabrics. The image of a Roman blind on the left is taken from The Thermal Blind Co web site.

The curtains used in the report were of the traditional, side drawn, type and made of heavy fabric.

The curtain on the left,  an example of one made of special thermal materials, would probably exceed the insulation of the traditional type used.
Available in a vast range of styles, including honeycomb as shown on the left and which are particularly effective insulators.

Blind pr
ices start from from the relatively inexpensive plastic venetian type. Material options can be translucent and so could be used during the colder winter days without too much loss of light. Available in a wide range of designs. The image on the left is taken from the Crosby Blinds web site

The report carried out tests on two types of roller blind. A standard roller blind and the Victorian version which operates within a frame and is therefore better fitting and offers more insulation.
Secondary Glazing   The image on the left is taken from the ecoease web site. A manufacturer of made to measure of DIY secondary glazing products.