1 Darlington Place, Bathwick, Bath

1 Darlington Place forms part of a Grade II section of early 19th century terraced dwellings, situated within the Bath City-Wide Conservation Area and World Heritage Site. The building forms part of the grouped value and setting of other individually Grade II listed terraced dwellings along Darlington Place. Whilst there is a greater diversity of height, architectural detailing, and material additions and extensions to the southern end of the terrace, 1-7 Darlington Place remain unified in their strong visual uniformity and balance, and use of defining features such as a two storey ‘stack’ on the street-facing, ‘rear’ elevation as part of the main access to each dwelling. As existing, the terrace retains the homogenous use of its traditional-style multi-pane sash windows across its street-facing façade looking onto Darlington Place, with 6-over-6 pane sashes across the main building and 3-over-3 sashes at second floor level. There is greater variation across the west elevation where a number of windows across the terrace have been replaced with single pane sash windows. No. 1 incorporates a number of windows of what appear to be a later fenestration design at lower ground floor to the front and rear; the rear sash-style casement window is steel-framed.

In response to the Climate Emergency, BPT is generally supportive of sensitive energy retrofit measures, where deemed appropriate, within the historic environment, as well as the sympathetic upgrade of listed housing stock to better meet modern standards of living. We therefore note a positive opportunity for the sensitive implementation of energy efficiency retrofits and associated thermal improvements where this does not result in harm to, or the loss of, significant historic fabric.

There is some slight confusion regarding the scope of proposed window works, where the D&A Statement sets out the following: “Fineo vacuum glazing, double glazing and magnetic taped acrylic secondary glazing plus draught-stripping to all windows and external doors as shown in schedule.” Based on the window schedules provided, it is presumed that all existing windows would be retained and fitted with secondary glazing, with the exceptions of windows W.405.A, W.002.A, W.001.A, and W.101.A, as well as the glazed door, and our comments are offered on this basis.

We are supportive of the principle of installing magnetic secondary glazing as a less invasive and easily reversible retrofit measure to improve the thermal performance and residential comfort of a historic building and ensure its long-term, sustainable use, although we note the overall benefits resulting from the installation of secondary glazing should be considered as part of a ‘whole house’ approach. Draught proofing works would further improve the energy efficiency of the existing windows and reduce loss of heat.

The upgrade of the loft insulation as part of general roof repair works is supported.

Where it is proposed to install a double glazed casement window in the front elevation at lightwell level, we recognise that the window would be of fairly limited visibility but express a preference for the use of a slimlite double glazing of an approx. 12mm-14mm where this would be more compatible with the fenestration thickness and style of the listed building.

It is further proposed to replace the existing rear sash-style casement window at basement level with a vacuum double glazed timber sash window. The works would be considered to offer the following benefits:

• The replacement of a materially inappropriate windows to the rear, and an opportunity to reinstate windows of a more appropriate materiality and profile.
• Reinstatement of a traditional-style sash window.
• Upgrade to high-performance double glazing and resulting improvements to energy efficiency and the windows’ thermal performance, though we maintain that any energy efficiency gains need to be considered from a holistic, ‘whole house’ perspective, which considers the ‘energy hierarchy’, including behaviour change and measures to reduce energy waste.

Similar comments are also raised regarding the proposed replacement of the 2-over-2 sash window at lower ground floor, which is evidently a later addition on grounds of its fenestration style (though this would be replaced in a like-for-like style).

BPT has generally expressed concerns with the appearance of the micro-pillars between the glazing panes and how this would impact on the general appearance of a listed building. We continue to express an in-principle opinion that the use of applied glazing bars would be an incongruous addition to a listed building and would fail to sustain the traditional construction qualities associated with its special architectural interest. We continue to reiterate a strong preference for the use of through glazing bars, though in this particular case, we acknowledge that the proposed vacuum glazing installation works would be focused on a single window at lower ground floor level on the west elevation and as such would be of very limited visibility and associated harm.