Windows
Replacing historic and single glazed windows is one of the most common energy improvement measures owners seek to do to their traditional building. Whilst for many buildings, this can be done without consent (although some restrictions may apply if you live in a conservation area), an application for Listed Building Consent would need to be submitted to the Council for this if the building is listed. For more information on the importance of historic windows, please visit the Council’s Historic Windows page.
If you live in a listed building, there are various things that you can do (often without Listed Building Consent), to improve the energy efficiency of old single glazed windows. However, the first thing you should do is make sure you overhaul and repair your windows. This not only will help to improve how well they work but will reduce unnecessary waste by replacing them when they still have several years of life left in them. It should always be borne in mind than many historic windows can be over 100 or even 200 years old and with good maintenance could last much longer. Modern windows, by contrast might only last 10-20 years depending on their quality and location.
Improving the efficiency of existing windows
If you are looking to keep your windows, but make them more efficient, once you have had any necessary repairs done to them (please go to the Getting Help page for information about finding carpenter joiners) you can look at doing the following:
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Install draught-proofing.
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Installing low-E (low emissivity) window films.
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Using shutters in the evening.
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Reinstating internal shutters if they have been removed or no longer work.
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Installing secondary glazing (if the window reveal is deep enough, you could have double-glazed secondary glazing). If you install secondary glazing, then the single glazed windows should not be draught-proofed to reduce the chances of moisture and mould between the window and the secondary glazing.
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Install thermal curtains and blinds.
Most of these works would not require Listed Building Consent, although reinstating missing shutters may require Listed Building Consent. There are also some instances where secondary glazing will require Listed Building Consent if there are shutters or panelling in places. If you need further advice, then you should use the Council’s pre-application advice service.
Replacing existing windows
Where you are replacing existing windows in a listed building, it will be expected that a condition survey is submitted with a Listed Building Consent application if the windows are historic. Please go to the Window Condition Survey Example for this. If replacement is agreed, then it would be expected that the replacement window meets certain criteria:
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Uses a suitable hardwood, European softwood, or metal. uPVC will not be considered acceptable.
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Has traditional ‘through’ glazing bars. Applied/plant on glazing bars or lead cames will not be considered acceptable.
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Slim line double-glazing (6-14mm). They are several different types of double-glazing products available. The most effective ones have a vacuum rather than gas filled.
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Flush detailing, not storm-proof.
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Traditional manner of opening.
Some investigation should also be done to see whether the existing window frame can be retained and only the glass replaced with thermally efficient single glazing or slim line double-glazing.
For all replacement applications, it is necessary to submit scaled drawings of the proposed windows. The required scaled drawings are:
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Elevation at 1:5
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Cross section at 1:5 (horizontal and vertical)
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Glazing bar detail at 1:1
If these drawings are not provided, it is likely that the application will be refused due to insufficient information being submitted.
Further information
Cotswold District Council has produced a guidance document on windows and includes examples of the type of scaled drawings the Council expects to be submitted. This guidance is called Traditional Casement Windows.
Historic England has produced serval very helpful documents and web pages on improving the energy efficiency of windows. These are useful for all traditional buildings with historic windows not just listed buildings:
Documents
Draught-proofing Windows and Doors
Traditional Windows: Their Care, Repair and Upgrading
Web pages
Repair or Change Windows in an Older Home
Windows - pdf - 110 Kb