Ground And Garden Flat, 18 New King Street, Kingsmead, Bath
18 New King Street forms part of a terraced pair of Grade II* mid-18th century townhouses at 18-19 New King Street, situated within the Bath Conservation Area and World Heritage Site. It forms part of the cumulative grouped value of a high concentration of Grade II terraced buildings along New King Street to the east and west. The broader terraced character of the streetscape is generally homogenous in its 3 ½ storey height and use of Bath stone ashlar, although its aesthetic uniformity has been unbalanced over time due to later alterations, particularly in relation to changing designs in window positioning and fenestration styles, door positions, and decorative surrounds. Both Nos. 18-19 are attributed heightened significance due having “witnessed discoveries of the greatest magnitude” (Historic England), most notably Sir William Herschel’s discovery of Uranus from his garden in 1781.
The building as existing features a later single storey lean-to extension at lower ground floor level that spans the width of the rear façade, most likely attributed to 1993 as a replacement of an earlier conservatory extension (see LB-10345-5). The extension is currently accessed by a rear door from the living room which also incorporates a window opening.
In the interest of transparency, we highlight BPT’s role in the ownership of the neighbouring property at 19 New King Street, run as the Herschel Museum of Astronomy.
We have limited heritage concerns regarding the proposed rear extension, only to note that the provision of further information regarding the proposed widening of the existing access would be welcomed. Where the existing door and window would be removed, it is unclear as to their age or significance, or whether they were later insertions associated with the conservatory. We recommend that this detail of scheme is clarified with the case officer.
As part of proposals, we note the intention to upgrade the existing front and rear windows at ground and lower ground floor level to “painted timber-framed double-glazed sash units.” It is indicated that these would be slimlite double glazed in the As Proposed Details. Whilst BPT is generally supportive of the principle of window upgrades to improve the thermal efficiency of the building and reduce carbon emissions, where they form part of a ‘whole home’ approach that reduces energy use and waste, and improves insulation. We emphasise that retrofit measures should strike an appropriate balance with sustaining the defined special interest of a listed building, its character and appearance, and its contribution to the wider historic streetscape and the group value of multiple heritage assets.
We therefore maintain that the application as submitted does not provide a sufficient level of detail to be able to assess the degree of change, and related visual impact, to a Grade II* listed building. We recommend that further information as to whether the existing windows are of historic interest is submitted in support of the proposals, although the existing use of single pane glazing is likely indicative of later 19th century replacements.
Where double glazing is proposed, we therefore strongly recommend that further details are provided, including relevant elevations and sections of the existing and proposed windows to enable proposals to be assessed proportionate to the high level of significance of this Grade II* listed building. Where windows are of a non-historic design and the proposed design of replacement windows would be of an appropriate traditional-style fenestration and profile, BPT is supportive of the opportunity to implement sensitive energy efficiency retrofits with minimal harm to historic fabric.
However, we do encourage consideration of measures as part of a ‘whole house’ approach in which interventions are considered holistically across the entirety of the building, as well as in conjunction with other available measures (eg. insulation).