Appeal 3342924

The appeal is dismissed.

The main issues are the effect of the proposal on the character and appearance of the host building and whether it would preserve or enhance the character or appearance of the [address] Conservation Area.

The appeal property forms part of a handsome terrace of late-Victorian, 3-storey houses that feature canted bay windows at ground and basement levels and decorative window heads and entrances. There is a similar terrace on the opposite side of this pleasant tree-lined residential street.

The terrace forms a major part of the [address] Conservation Area (CA) which is notable for high-quality housing that retains many of the original architectural features. In particular, most houses appear to retain their original timber sash windows with their distinctive arrangement of glazing bars. In some cases, including the appeal property, original translucent dimpled glass is also evident to the edges of the principal windows. The street-facing windows contribute to the highly uniform appearance of the terraces and make a significant positive contribution to the overall appearance of the area, matters to which I attach significant weight. This is reflected by the fact that permitted development rights have been removed in respect of window replacement in the CA.

The proposal would comprise the replacement of the single-glazed windows in the front elevation of the appeal property, excluding the basement, with double-glazed timber sash windows. These would include 18mm thick clear glazing units with metallic spacers and internally and externally applied glazing bars. The application drawings indicate that these glazing units would be accommodated within frames that largely duplicate the existing ones.

I recognise that the proposal would not materially change the layout of the windows. However, the depth of the glazing units together with the metallic spacers and applied glazing bars would result in a perceptible change to the overall frontage of the appeal property that would be jarring in this particular context leading to unacceptable harm to the character and appearance of the host property and a failure to preserve the appearance of the CA.

Whilst the proposal would fail to preserve the character and appearance of the CA, the harm to this heritage asset would be less than substantial. In these circumstances Paragraph 202 of the National Planning Policy Framework (2021) requires me to weigh the harm against the public benefits of the proposal. I am acutely conscious of the need to make homes more energy efficient and to reduce on-site greenhouse gas emissions. In this respect the proposal would result in a public benefit.

However, both the appellant and the Council refer to advice1 on the many options for improving the thermal performance of windows whilst respecting architectural integrity. Whilst some of these options have been considered I am not adequately convinced that the energy efficiency benefits that would be achieved by the appeal proposal cannot be achieved by others means. For this reason I do not consider that the harm resulting from the proposal would be outweighed by the public benefits that would result.

In coming to the conclusion above I am conscious that the appellant’s [name] identifies one of the aims of the proposal as being to gain clarity, for the benefits of all owners of similar housing in Islington, on design details that are acceptable aesthetically, technically and not disproportionately expensive.

For these reasons I conclude that the proposal fails to accord with Policies DH1 and DH2 of the Islington Local Plan Strategic and Development Management Policies (2023) which require development within conservation areas to conserve or enhance the significance of the area. There is also conflict with the aims of the Framework, the [name] (2017) and the [address] Conservation Area Design Guidelines (2002), which seek to ensure alterations blend with and reinforce the appearance and character of an area.

For the reasons set out above, and having regard to all other matters raised, I conclude that the appeal should fail.