We were heartened to hear embodied carbon and retrofit discussed at the Housing Scrutiny Committee on 8th December. The ability of retrofit to reduce carbon emissions over the next 20 years is of prime importance to mitigate climate change. The problem with the ‘whole life carbon’ methodology that is often put forward to justify demolition and rebuild is that it looks at carbon emissions over a 60year period, which is too long when we need urgent change to growing rate of carbon emissions. This is now considered by many to be a form of ‘greenwash’.
In 2019, RIBA funded research showed that a retrofit scheme for West Kentish Town estate using natural and low carbon materials, including adding an extra storey to the 3 storey buildings and providing external balconies to all flats, could be achieved for an embodied carbon cost of 9,000 tonnes C02e.
In comparison the demolition and new build scheme approved by Cabinet in 2019 would cause the emission of 87,000 tonnes C02e. Most of these emissions are Scope 3 emissions caused by the manufacture and transport of cement, steel and other building materials outside of the Borough of Camden.
Retrofitting the estate would therefore save in the order of 78,000 tonnes C02e emissions. This is more that the 75,000 tonnes of C02e resulting from the heating and powering of Camden’s 33,000 council homes each year, a carbon cost that Camden is hoping to minimise by spending £500m. Current plans for retrofitting council homes, not yet funded, would reduce this carbon cost by a mere 270 tonnes, a negligible amount in comparison.
If a retrofit scheme were considered by Camden, it is likely that some new homes would be built to provide a full range of larger units. In this case the overall embodied carbon would still be a fraction that resulting from building 880 new homes- some in carbon intensive, high-rise buildings- as currently proposed by Camden.
Research shows that a retrofit scheme for West Kentish can provide good quality homes that meet housing standards. One of the problems to be overcome is acoustic separation between flats. People would need to move out as the internal refit would be extensive. However it would be significantly cheaper and less disruptive to build. The configuration of the neighbourhood would not be utterly transformed and existing relationships between neighbours could survive.
A retrofit solution will enable more of the green space and mature trees around the existing buildings to be retained. The council’s demolition and rebuild proposals involve the loss of much of this green space and many trees. While the carbon sequestration capacity of the existing green space and mature trees isn’t huge it is larger than that proposed by Camden. It is now recognised that urban greening is important in providing a wide palette of solutions to tackle the climate and ecological emergency.
Built Environment Group, CEC