London and other cities should integrate public and private uses in high-rise double and triple-decker buildings to maximise available land, according to consultant WSP and University College London.
In particular, overbuilding apartments on top of NHS buildings could provide up to 77,000 new homes in London, says the team.
This would represent almost 20% of the 400,000 homes needed in the next decade according to the mayor of London Boris Johnson, with the added benefit of being able to redevelop ageing and unused healthcare facilities at the same time.
WSP has been working with researchers at UCL to map public buildings in London that would be suitable for overbuilding, including NHS buildings, schools, colleges, police stations and government offices.
Their report is due to completed in October 2014, and will be presented to the mayor, the GLA and central government.
WSP says that mixed public and private high-rise “sandwich” schemes are a feature of several cities, including New York.
Director Bill Price told CM: “We’ve been involved in examples such as the Beekman building, where the bottom four floors are a school, then there are hospital administration offices and residential on top.
“It involves private developers working with the public sector, and looking creatively at the traditional delivery models. But I think the difficulties could be overcome: the public sector is constantly struggling for money, and private developers are already funding infrastructure via the Community Infrastructure Levy or Section 106. And it keeps the integrity of the city.”
New York’s Beekman building, designed by architect Frank Gehry, is a sandwich of school, hospital and residential apartments
However, Price acknowledged that widespread overbuilding would require changes to the use categories in the planning system, on what is deemed acceptable on the heights of buildings, and for more private developers to be prepared to invest in air rights, changes that he said could take place only in the medium term.
To bolster its argument WSP refers to a recent report by the London Health Commission, which found that £50m-£60m was being spent annually on maintaining NHS buildings that were either not used or not fit for purpose.
WSP’s estimate of 77,000 new homes above NHS facilities is based on an analysis of 79 existing NHS buildings in London, allowing for 100m² per apartment and using a mixed height overbuild development strategy, with a combination of six, 12, and 18 storeys.
It only considers hospital buildings without A&E facilities, which would cause specific planning and construction issues.
Price added: “The point is not that we should go out and redevelop every hospital into an apartment block, but that we need to start thinking creatively about our housing woes, challenging the status quo and looking at how we use the land available to us.”
He said that overbuilding did not raise any difficult technical issues, and also that we should rethink the assumption that public services belong on the ground floor, arguing that it would be feasible to put hospitals above ground-level retail.
