Edward Nash Architects, 23A Sydney Buildings, Bathwick, Bath
23A Sydney Buildings is a Grade II early 19th century former Coalhouse, situated within the Bath Conservation Area and World Heritage Site. The building occupies a low single storey presence as part of the Sydney Buildings streetscape, increasing to two 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 Nos. 17-20 (albeit of a much larger and grander scale).
The building has been subject to a number of internal and alterations in 1988/1989 when it was first converted to office use, including the reconfiguration of the Sydney Buildings elevation and the addition of a glazed dormer, expansion of the existing window reveals on the west elevation to form a double height glazed reveal, and replacement of the corrugated asbestos roof with natural slate to include rooflights to the north and south. Further works included alterations to the interior, with the addition of partitions and circulation spaces. The key areas of retained historic fabric which are attributed high significance as part of these works are therefore the external walls and the internal roof structure, in which an exposed series of king trusses and purlins have been retained and discreetly reinforced.
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 commend the use of a holistic, ‘whole building’ approach which considers a range of thermal improvements using the PHPP to model the overall energy balance calculation. The consideration of Passivehouse principles in relation to a listed building and the adaptation of historic fabric remains unusual, and these proposals would be an exemplary example of low-carbon retrofit which could inform other similar measures in Bath’s historic and traditional buildings, where these are executed to an excellent standard.
Where measures such as the application of roof and internal wall insulation would have some minor adverse impact due to the obscuring of historic fabric and detailing, we note that alternative options have been considered and discounted due to resulting greater harm to heritage significance. The current options as proposed therefore demonstrate a balance of the least possible harm whilst facilitating the public benefits of reduced carbon emissions brought about through improved thermal efficiency and a lessened reliance on the existing fire gas boilers whilst also creating an exemplar of listed building retrofit to inform and inspire the wider community to take action.