Kilowatt House , North Road, Bathwick, Bath

Kilowatt House is a Grade II 1930s detached dwelling, situated within the Bathwick Hill character area of the Bath conservation area and World Heritage Site. The house was originally designed by Bath architect Mollie Taylor for the acoustic engineer Anthony Greenhill with the incorporation of on-site sound studios. The building can be attributed to the Art Moderne movement due to its form, horizontal emphasis, and asymmetrical layout. The mix of sharp, 90 degree angles and curving lines is indicative of a blend of Art Moderne and Art Deco principles. A defining feature of the building is its extensive use of Crittall glazing (largely replaced in a similar style in the 1970s) including wraparound windows and a full-height window up the rear circulation core. Permission has since been granted to replace all windows with like-for-like slimlite double glazing (see 19/04469/LBA), of which BPT was supportive pending further design and heritage details.

• In principle, BPT is supportive of the opportunity for energy efficiency retrofits and the installation of microrenewables where this is compatible with the special architectural or historic interest of a listed building.
• We are supportive of efforts to improve the energy efficiency and associated liveability of this listed building. It has been evidenced that the building is a challenge to heat and run in a way that is compatible with modern residential standards.
• The use of ballast-mounted PV panels would be a reversible, lighter touch alternative for installation without requiring fixings to possible historic fabric, which we support. The proposed PV solar array on the central flat roof would be suitably obscured from view behind the parapet.
• It is noted that the proposed array on the flat roof of the west wing would have some limited visibility in immediate views of the building, although the site is set back from North Road and well-screened from public views.
• In accordance with paragraph 202 of the NPPF, “where a development proposal will lead to less than substantial harm to the significance of a designated heritage asset, this harm should be weighed against the public benefits of the proposal including, where appropriate, securing its optimum viable use.” We consider that this less than substantial harm is therefore outweighed by the benefits of ensuring the long-term sustainable use of this building.
• We consider there are other possible opportunities for retrofit, such as internal insulation improvements where a variety of later interventions have been identified. The Heritage Statement indicates that in places the original fibreboard acoustic shielding has been removed and “replaced in different rooms with a variety of coverings including: double/triple-skinned plasterboard affixed directly to the Pioneer block/concrete; plasterboard mounted on softwood battens with a variety of fillings such as mineral wool, PIR board, expanded polystyrene panels or none.” We continue to advocate a ‘fabric first’ approach as part of a whole house retrofit to ensure that the thermal efficiency of existing fabric is maximised and to minimise the need for energy consumption. The benefits of this approach have already been identified with regards to the ongoing upgrade of windows with slimlite double glazing.
• We are keen to work with applicants to monitor the results of installation and prospective energy savings as a ‘best practice’ case study for microrenewable installation on Bath’s 20th century housing stock as well as examples of more unusual listed building typologies within the district.