The International Garden City Retrofitting webinar held last week brought together planners and built environment professionals from across Europe. We heard about case studies from Paris, Belgium and London, on how they have devised and applied retrofit frameworks to their garden city developments.
The first presentation – ‘From Garden City to Climate Suburb Leuven’ – drew on using neighbourhoods as a lever for urban climate transition. The town has 100,000 inhabitants, 30,000 students and is located 30km from Brussels. The session highlighted the measures and guidance proposed to maintain the heritage and character of the town, whilst creating adapted infrastructure to suit rising temperatures and increases in rainfall, including ‘The Roadmap 2025 · 2035 · 2050’ , drawn up by Leuven 2030.
The retrofit framework includes guidelines on preserving the ensemble of the original architecture, such as using the same colour materials as the original walls, roof and windows, and directing owners to choose from the same selection of materials to maintain uniformity. It also highlights the benefits of de-sealing of soil and greening front and side gardens, as well as demonstrating where this should be done on central squares within the neighbourhoods, alongside preserving mature trees and providing street furniture to encourage social cohesion.
Regarding energy provision, the framework suggests collective integration of individual heat pumps is the most flexible option and has the least impact aesthetically. The presentation also covered the all-important ‘vision to reality’, taking account of the private financing capacity of the residents, as well as ensuring a private-public collaboration. This means using the public realm as an incentive for residents to adapt their houses to a changing climate.
By providing an improved experience of the public realm (for example by urban cooling provided by tree canopies or sustainable urban drainage systems (SuDS) preventing surface water collection) communities can experience first-hand the positive impact of implementing and investing in green infrastructure interventions and mitigation measures and be encouraged to do the same for their own residences.
It was interesting to hear how Leuven is actively providing retrofitting support to its communities, by bringing together partners to provide an extensive range of services in cooperation with the market. This helps increase the rate of regeneration of residential buildings and provides detailed measures for inhabitants to follow in retrofitting their own homes. It was also reassuring to see the care and detailed measures considered to retain the original garden city principles that were applied when they were first built.
Next, we heard from Hampstead Garden Suburb Trust, who spoke on ‘Retrofitting guidelines in a heritage context Hampstead (UK)’. It was interesting to learn that the entire area is protected as a conservation area, designated in 1968 by the local government, and that the trust operates a scheme of management which was approved by the High Court in 1974, under the Leasehold Reform Act 1967. The scheme continues to act as a landlord by controlling the external changes to properties and the sole purpose of the trust is “to do all things possible in order to maintain and preserve the present character and amenities of the suburb” and therefore its position on retrofit must fall in line with the above statement.
In the presentation it was acknowledged that there are problems with the performance of traditional housing, including uninsulated lofts and cavity walls, single glazing and homes originally built to be heated solely by coal fires. As a result, the trust has provided guidance for residents in how to thermally upgrade their properties without changing the outside appearance. However external wall insulation is deemed too damaging to be approved planning permission, as it would require major works and changes to the window openings and eaves, which could obscure the traditional architectural details. The trust recommends specific timber and steel manufacturers and suppliers who can provide double glazing replacement windows in a traditional architecture style; however, where windows have been panelled with lead, often the risk of loss of character is deemed too high for these to be replaced and secondary glazing is recommended instead. But in general, the trust encourages a ‘whole house’ approach, considering the entire fabric of the property when deciding what adaptation measures are suitable.
By providing an improved experience of the public realm communities can experience first-hand the positive impact of implementing and investing in green infrastructure interventions
Moving towards more efficient energy generation technologies is encouraged, where they can be incorporated discreetly. However due to the unique roof scape in the Suburb, which is of special interest to the area’s character, there is little scope for installing solar panels in ways that would not disrupt the original features of the houses. The steep tiled rooves, which are also a feature of the town’s early twentieth-century architecture, add to this limitation and could be damaged in the process of trying to effectively position and attach solar panels. Although there are cases where they have been successfully installed on flat roofs, such as that of rear extensions or garages. In regard to heating, applications for ground source heat pumps have not been common in the area but can be accommodated in large gardens that allow them to be discreetly installed, the same goes for air source heat pumps, which can be screened by planting or timber frames.
Despite the area being limited by its historic nature, in terms of adapting its residential buildings, the wider garden suburb has environmental advantages. These include large areas of planting and green space with multiple mature trees proving urban cooling effects, plus the strict restrictions on development which maintain these open areas and garden land.
It is encouraging to see garden cities across the UK and Europe using retrofit guidelines to help residents take steps towards adapting their houses and neighbourhoods to mitigate the negative effects of our changing climate and enhance the experience of public spaces. It was particularly interesting to hear in depth about the governance structures and role of the management trust in Hampstead, as having a stewarding body is an important but often overlooked feature of the original Garden Cities.
More on the legislation and policies around setting up a management organisation in new and existing communities can be found in our Stewardship Toolkit.