Assembly Rooms, Bennett Street, Bath
Update 21st August 2024
SUPPORT
The original comment provided by BPT in response to 23/04801/FUL and 23/04802/LBA was supportive of the majority of proposals within the submission but encouraged further review and engagement with options, which aim to satisfy the requirements of the NPPF with regards justification of harm and relative public benefit.
Following the original application and various responses, the architects provided the opportunity to view a sample of the proposed sash window option along with the rationale for how the Fineo vacuum-glazing option was selected.
The options appraisal is well reasoned and pragmatic and demonstrates significant consideration of the visual impact with justification, given the location of where it is to be installed. It directly responds to and appears to resolve our first substantive concern in our submission of 15th February 2024.
The options appraisal and samples also serve to demonstrate that the concerns expressed in our second substantive concern have been addressed.
We are grateful for the attention to detail and opportunity to see samples and engage with the architects directly and pleased that our legitimate concerns have not only been accepted but also responded to. It is felt that the options appraisal responds positively to paragraph 208 of the NPPF.
Previous, superseded submission of 15th February 2024
The Bath Assembly Rooms are a grade I listed building of very high heritage significance, and a very important element contributing positively to the character and appearance of the Bath City-Wide Conservation Area, and the significance and Outstanding Universal Values of the dual World Heritage Site inscriptions through its architectural, aesthetic and historic value as a building representing the work of the architect John Wood, the planned city, Georgian society and social community, and Palladian and Neoclassical design.
BPT are supportive ambitions to improve the building’s environmental performance and accessibility, to ensure an equitable visitor environment and experience. We commend the heritage impact assessment which allows for an informed assessment of harm versus the public benefit of improving access and a decarbonised future for the site. While BPT has had the opportunity to comment on the design development, some important design details have been completed on submission of this application. Our comments therefore relate directly to these elements where we have not yet had the opportunity to discuss the approach. As well as to the broader need for intervention.
While the broad aims of the redevelopment proposals are supported we feel there is scope for improvement in line with our comments set out below.
COMMENT
Layout and Internal Alterations
The historical research is exemplary and the colour-coded phasing analysis is helpful in explaining the rationale.
The proposed creation of a new principal staircase would replace the existing 20th century WC staircase and shop space on the southern side of the main lobby, indicated to have formerly been one of a pair of flanking lightwells that have since been infilled. We acknowledge that this proposed intervention is focused in an area of 20th century fabric, and consequently an area of lesser historic sensitivity. The 1950s twin staircases are a bit of an extravagant use of space and their removal creates beneficial opportunities to improve visitor circulation and create a new, innovative addition to the building whilst minimising potential harm to the building’s special interest or material integrity. It will, nonetheless, be important for this application to include the detailed design of the new staircase.
The new lift position seems to make sense, linking the basement loos to the main corridor and upwards to the meeting rooms on the upper floors. We note that ancillary spaces associated with the two performance spaces (the Tea Room and Ballroom) which could be used as a green room have been eliminated. As shown there would be nowhere for performers to emerge from on to the stage or exit into.
We encourage the opportunity to remove later non-historic finishes and better reveal areas of high architectural significance, such as the cross vault at basement level. Other modern interventions are indicated to be retained (e.g. the lining of the original walls in blockwork in the basement space below
the Ballroom), therefore we note and further encourage potential to reveal and restore historic fabric in future phases of work.
The Infill Extension
We support the infill extension. While classically referenced the new ‘colonnade’ east of the Ballroom includes contemporary detailing which speaks of its time.
Energy Efficiency Retrofit Measures
We are supportive of the ambition to reduce carbon emissions through deep retrofit, thermal upgrades and renewable energy. Opportunities for the improved energy efficiency should be considered in accordance with the energy hierarchy, looking at issues such as heat loss/leaks and drafts, and associated overconsumption of energy, as part of the overall vision for the building as an exemplar of sustainability. The pre-application proposals discussed potential options for internal insulation, increased airtightness, and thermal improvements to glazing – alterations to glazing should not be considered without the former having been implemented. While there are pretty limited opportunities to improve the U-value of walls as all the big spaces have the largest wall area, but are also on display! It would be interesting to know whether any research was done on this, given that the interiors are all a post-War reconstruction.
Sash Window Upgrades
The existing sash windows date from the 1950’s therefore the significance of the fabric is low and presents opportunity for energy efficiency improvement which sustains the heritage significance of the building and its setting. The principle of replacing 20th century windows is supported, and BPT has an in-principle position which supports slim-profile timber sash window double glazing in these circumstances.
However, we have strong reservations regarding the design proposed, which details the retention of sash boxes with the installation of vacuum glazing and applied glazing bars. While recognising that both slim profile double glazing and applied bars represent contemporary interventions, constructed by modern methods, and neither would entirely uphold the craftsmanship, authenticity and integrity of a traditionally constructed sash window. The main difference between the two modern windows will be in the appearance of the glass and the bars. And whether the bars are read as being split either side of the glass – this would not give the appearance of a traditional sash window the same way as slim profile window with internal glazing bars does. The glazing will also potentially be speckled or have different reflective qualities.
In addition, we have strong reservations regarding the durability and longevity external beads glued on to sheets of glass that are subject to temperature variations (especially on the Alfred Street side) and rainfall. This will be especially true of the ‘Gothic’ traceried window heads to the east side of the octagon. We are concerned that any success in concealing the fact the glazing bars are split either side of the glass (helped by the thin dimension of the glass) would soon be undone by weather conditions.
Further discussion with stakeholders is encouraged to allow for the proper consideration and trialling of this innovative intervention as the most appropriate solution for this building and other historic
properties of high significance, in heritage settings of high significance, with necessary safeguards for risk/harm mitigation and reversibility. And if anyone can do this, the National Trust can.
PV panels and ASHP
BPT supports the principle of PV panels on concealed roof slopes with restricted visibility. Elevations of lesser visibility and associated significance should be prioritised where possible. As anticipated, some PVs have been incorporated into the only feasible space: the south facing but little seen slope of the hipped slate roof of the ballroom. Divided into two by the central cross-roof to the octagon, the available space is limited, but it is good to see the effort made. The impact of the slight view of solar panels could be further limited by dropping the position (from sightline view) below the balustrade when entering the forecourt from the south.
We encourage the submission of a wider LVIA to enable a proper assessment of the roof level ASHP and solar PV and their potential impact on long distance views.
Replacement Flooring
The proposed replacement of the early 20th century floors in the Ballroom and Tearoom should be appropriately justified as to the associated public benefit (e.g. reinstating a more traditional flooring finish in keeping with the historic qualities of the building). Whilst these do not constitute historic fabric and as such are of limited contribution to the historic significance of the building, there should be justification as to what benefits removal would offer in a broader context, considering emphasis on low carbon build and minimising loss of embodied carbon where the project is emphasising the sustainable use and future of the building.
The NPPF
We draw attention to new paragraph 164 in the National Planning Policy Framework (NPPF, December 2023) which requires local authorities, in determining planning applications, to give “significant weight” to the need to support “energy efficiency and low carbon heating improvements” through adaptation of buildings. This represents strong in-principle policy support for improving energy efficiency.
Alongside paragraph 205 which sets out that ‘when considering the impact of a proposed development on the significance of a designated asset, great weight should be given to the asset’s conservation (and the more important the asset, the greater the weight should be)’. ‘Any conflict between its conservation and any aspect of the proposal should be avoided or minimised’ and any remaining harm should be clearly and convincingly justified. (Paragraphs 201; 206).
Any harm identified that will impact on the overall heritage significance of the asset should be considered against the requirements of paragraph 208 of the NPPF. This states that ‘this harm should be weighed against the public benefits of the proposal including, where appropriate, securing its optimum viable use’.
Position
For the reasons set out above BPT cannot fully support the proposal in its current form and encourages further revision, in particular to resolve the approach to the windows – which is a design detail far too important to be dealt with by Condition. We highlight the need to satisfy the requirements of the NPPF through the planning balance of harm and public benefit, and the mitigation of harm through further revision.