Upwards & Onwards: Central London rooftops could hold the key to 41,000 new homes

New airspace mapping tool estimates more than 28 million sq ft of potential additional resi floor area could be developed in the capital, with a potential value of £51 billion

With rumours circulating that new “rights to height” could make an appearance in next week’s Budget, a timely new tool has been launched to map the scale of the opportunity currently sitting above London.

Proposals mooted by Sajid Javid in February’s housing white paper pitched the relaxation of planning laws around upwards extensions as a neat way of helping with the capital’s worrying supply issues, and it sounds like Phillip Hammond is on board.

Envisaging the real potential of the capital’s airspace is, however, significantly trickier than looking at swathes of land, so Knight Frank has come up with a helpful new tool called “SKYWARD” to assist developers and policymakers alike.

The clever geospatial mapping software analyses 3D spatial data from the Ordnance Survey, cross referencing Land Registry data to assess ownerships, and Historic England data to filter out listed buildings, to churn out an analysis of the potential of each individual property.

It’s fascinating stuff, and the team has used the tool to estimate that as many as 41,000 new dwellings could be built in central London using rooftop development space alone – crucially without altering the iconic skyline. According to the workings, there’s more than 28 million square feet of potential additional resi floor area available, worth an estimated £51 billion.

In Zones 1 and 2 alone, there’s 23,000 square feet of “untapped” space in the offing, with a volume equal to eight Burj Khalifa towers (830m high).

Charles Dugdale, Residential Development partner at Knight Frank: “Skyward is a fantastically powerful tool for identifying development opportunities to unlock thousands of new homes in London and ease housing supply pressures, particularly in those areas where availability of land is becoming increasingly rare. It also has the potential to add an objective approach to planning decisions on a semi-permissive basis.”

Ian McGuinness, Head of Geospatial at Knight Frank: “Using 3D mapping technology the findings of this analysis can be related to other geographies easily, including to client land ownership portfolios. We can now say where the opportunities are, how much value they unlock, and which land owners are best placed to drive this transformation.”