The Malthouse, 17 – 20 Sydney Buildings, Bathwick, Bath
The Malthouse, otherwise known as Baird’s Malthouse, is a Grade II listed mid-19th century malthouse situated within the Bath City-Wide Conservation Area and World Heritage Site. The building occupies a low single storey presence as part of the Sydney Buildings streetscape with a blank façade in Bath stone blockwork with the exception of a single centralised door access, increasing to 2 ½ storeys where it overlooks the Kennet and Avon Canal to the west. This continued prominence as part of the Canal’s built setting is indicative of the building’s interrelated significance with the Canal’s industrial heritage, and contributes to an established warehouse typology in this area with other comparable examples, such as 23a Sydney Buildings, which is a smaller Grade II former warehouse.
It is indicated that the building has undergone a series of alterations as part of the works to convert it to offices in the 1970s, as well as a series of later works including the replacement of all doors and windows with modern single-glazed units, and the re-laying of the roof in natural slate in 2008. Where the proposed areas of works would be focused on the windows, doors, and roof, these are all areas of non-historic fabric and therefore any associated impact to the listed building would be limited.
In response to the Climate Emergency, BPT is generally supportive of decarbonising retrofits where this would reduce carbon emissions and contribute to reaching net zero targets while sustaining heritage significance. The suitability of material interventions is assessed on a case-by-case basis, taking into consideration the particular qualities of a building and how change may be effectively and sensitively accommodated.
We are generally supportive of the principle of upgrading existing windows and doors with slimlite double glazed equivalents. There would be limited visual impact where the windows would be in a ‘like-for-like’ single pane casement style. The existing doors are indicated to be a mix of different, later additions, and the use of a consistent, single design approach for their replacement would be considered an enhancement.
There is a practical question, for the applicants and the LPA, regarding the replacement of the Georgian wire glazed hips with natural slate and associated loss of natural light – there could be an opportunity to re-glaze these aspects of the roof with high-performance treble glazing to maximise thermal performance whilst retaining access to natural light for internal users.
It is presumed that the reference to the “installation of PIR insulation board between the rafters and a new plasterboard ceiling internally” forms part of the works to infill the Georgian wire glazing with natural slate. Any more extensive works to the interior of the building should be clarified with additional information.
Where it is proposed to integrate PV solar slates to the southern roof slope, BPT is generally supportive of the opportunity to integrate solar technology into the existing roof surface to generate low-carbon energy, though it is not specified whether the array would be connected to a battery to generate energy for the site, or would feed straight into the Grid. This is an exciting proposal to test the use of PV slates where this type of technology remains uncommon in Bath, and could form a definitive case study on the integration of solar across Bath’s historic building stock.
We note that the proposed slates would be situated on the south-eastern portion of the roof to maximise efficiency and focus installation on the part of the roof which is not overshadowed by adjacent development. Nonetheless, this part of the roof is of some visibility from Sydney Buildings, particularly the high pavement and in mid-range views from further south along the road, though closer-range views are somewhat restricted at road level by the adjoining boundary wall. Further information should be requested by the case officer to allow for the proper assessment of the degree of visual and/or material impact as part of the overall planning balance. Further information should also be requested to show how the slates would be installed and interact with existing slates, which should be clarified through the use of relevant sections. The provision of relevant samples in comparison with the existing roof surface would also be helpful to ensure a cohesive finish and avoid an obvious visual contrast between the PV and natural slates.
BPT would welcome the opportunity to monitor and share this approach to energy efficiency retrofit and would be enthusiastic to create a case study on the approaches and measures used at this property subject to listed building consent approval.