Double Glazing in Hambledon
In this section we consider Heritage Glazing. This is important for those living in listed buildings or the conservation area. We detail individual cases in Hambledon in order to learn from their experience, which should help those following in their footsteps. Dr John Thornton has kindly put together the following information:
Double Glazing and Listed Buildings in Hambledon
Buildings are listed as being of historical interest in order that their development can be more closely controlled and their essential character preserved. Listing is not intended to prevent any development whatsoever. Numerous listed buildings in Hambledon have been allowed to make alterations and additions; many of them quite extensive and significant.
The over-riding principles seem to be that (a) there is minimal loss of historic fabric and (b) the development does not erode the character of the building or the conservation area. These principles seem sound, and an appropriate compromise between preserving our stock of historic housing (and the character of the conservation area) and allowing houses to be adapted to modern living expectations.
However, these principles are not consistently applied to double glazing. “Double glazing” often conjures up the spectre of plastic windows lacking any sympathy with the building into which they are inserted. This does not need to be the case. Edinburgh City Council undertook an extensive study of the options for double glazing in listed buildings. (See the full report here: https://www.changeworks.org.uk/sites/default/files/Double_Glazing_in_Listed_Building.pdf). It concluded:
The project has demonstrated that appropriate double glazing can be successfully incorporated into listed buildings, improving their thermal performance and lowering their CO2 emissions without detracting from their historic character or appearance.
The project has also demonstrated the ongoing durability, practicality and adaptability of traditional Scottish timber sash-and-case windows, and shown how existing window patterns can be maintained without significant visual change.
This report recommends that such slim-profile double glazing systems should be permitted in listed buildings, both in Edinburgh and further afield, where there would not be a significant loss of historic material.
Within Hambledon we have at least two examples where this philosophy has been applied, backed up in one case by two planning inspectors.
Peartree Cottage (SDNP/12/00863/LIS). WCC permitted all the windows and doors to be replaced with slimline double glazing. (HE officer: “It is unusual to accept a proposal to replace all windows in a listed building. It is even more exceptional that they should go in as double glazed windows. However it is considered that the replacement of these windows will not result in loss of historic fabric since they have all already been replaced.”)
3-4 East Street (SDNP/13/04799/LIS). Conversion to one dwelling, including replacing an 1980’s bow window with a box window to the same outline as the previous shop front. Rejected by WCC but allowed on appeal. (But the harm needs to be balanced against the benefit of replacing the incongruous shallow bay and its unfortunate imitation bull’s eye feature. The existing window detracts from the intrinsic character of these houses and also reduces the quality of the street scene. The proposed window would be an improvement on what is there now because it would be better proportioned and would allow the symmetry of the building to be more readily perceived. … On balance I find that, taken as a whole the proposed replacement bay window and its double glazing would preserve the special architectural and historic interest of the listed building. I also conclude that it would positively enhance the character and appearance of the HCA. - Sukie Tamplin, Planning Inspector)
Greenfields (SDNP/15/05787/LIS). Here a doorway had been partially bricked up and a window inserted. The window did not match the originals elsewhere either in style (the sashes had horns) or the proportion of the glazing. Although it was rejected by the planning inspector on the grounds the application lacked detail, it was nevertheless clear that slimline double glazing would have been acceptable to him. (I was able to see at close quarters the recently installed slim-line double glazed shallow bay window at Nos 3 and 4 (now one house), which occupies a similar prominent position on this principal thoroughfare of the village close to the appeal property. Its 22mm wide glazing bars with white spacers between the two panes of glass make it very difficult to actually detect that it is in fact double glazed unless one stands right next to it. As such this window successfully matches the others on the street and enhances the character and appearance of the Conservation Area, as the Inspector in that decision stated it would. - Nick Fagan, Planning Inspector)
2 West Street (SDNP/22/00447/LIS). This property had previously been granted permission to replace all its windows; on the street elevation with single glazing and two windows on the SW elevation with slim-line double glazing. The later application was to change the single glazing on the street-facing elevation to slim-line double glazing. The initial response of the Historic Environment Officer South for WCC is summarised as “The proposal for slim line is not acceptable and is more harmful than the previously permitted scheme of single glazing and it would set an unwelcomed precedent for future applications on domestic properties. Recommend refusal.”
Later consideration by the same officer came to a rather different conclusion. “[The previous] consent also allowed for the replacement of two windows in the south-west gable end of the building, but with new 14mm thick 'ultra-slim' double glazed timber flush casement windows. … These two windows have now been installed and were examined in detail during the site visit. The presence of double glazing in those windows is not readily apparent, due to the finer profiles of the 'ultra-slim' 14mm thick units, the white spacer bars and the distorted reflection produced by the uneven drawn glass to the external face of the double-glazed units. … Following review of the detailed design of the existing double-glazed windows (which this proposal seeks to replicate), and the inobtrusive nature of that double glazing, it is considered that the use of double glazing in this instance would not harm the significance of the listed building. This relies upon the fact that this double glazing is of noticeably finer proportions than 'standard' 24mm thick double glazing and would seek to match the subdivision, means of opening, glazing bar pattern and frame profiles of the existing windows.”
In all of these cases the windows to be replaced were, in themselves, not of great historical interest, and the proposed replacements retained the special character of the conservation area - the two key principles generally applied to listed buildings. But they are not the only examples.
Manor Farm is a grade II* listed building in the heart of Hambledon. It had some double-glazed windows before it was listed. These have recently been replaced without the need for listed building consent as the replacements are like-for-like. They are craftsman-made timber windows which would certainly not look out of place to the casual observer.
Unlisted. There are also several unlisted building, particularly in East Street, which have double glazing. With one unfortunate exception these are all timber casements in a broadly traditional style which do not detract from the character of the conservation area or from the listed buildings which they frequently adjoin.
The Hambledon Village Design Statement, endorsed by the SDNPA, includes guidance on double glazing in listed buildings. HVDG30 states:
Where the repair of existing windows is not possible, replacement using tint- free slimline heritage-style double glazed units set in traditional timber sashes or casements may be considered. The replacement should match the existing, replicating the size, scale and profile of the existing mouldings and sections.
Provided there is no significant loss of historic fabric, and that the proposed replacements are in a style and construction appropriate to the building and the conservation area, heritage-style double glazing in listed buildings in Hambledon is supported by:
• The conclusions of the Edinburgh project,
• The lack of harm demonstrated by several examples in Hambledon,
• Two planning inspectors considering local cases, and
• The Village Design Statement, endorsed by the SDNPA.
• Double glazing should be permitted in these circumstances.
• Secondary glazing should be considered only where the existing windows have historic value and are repairable.