According to the housing white paper[1] published in 2017, nearly 300,000 new homes are required per year to meet the demand for housing but on average only 160,000 are being delivered. In order to achieve the number of homes necessary in this housing crisis, government and local authorities are looking to infrastructure and other landowners to bring forward land which could be used for residential use. These parcels of land in major cities around the country are often small, geometrically complex or highly constrained. In order to maximise the land use in cities while maintaining a balance with green spaces, such as the metropolitan green belt around London, these plots of land need to be strongly considered in any appraisal of developable land.
For this land, the density matrix approach, in which the site area is multiplied by a particular factor to obtain an estimate of the number of units it can support, is not always suitable.. Some sites may look promising due to their area but geometrically be long and thin restricting the area which can be built on. Some sites may have limited access locations that mean ensuring a route from those points to any block around the development can have a significant impact on the number of units achievable.
SiteSolve, our generative design massing software, allows these geometrical constraints to be considered from the outset. Our unique algorithm ensures that blocks are optimised to fit onto sites of any shape and ensure connectivity to any specified access points. In our recent Mass Land Viability Study for TfL, we undertook a few different studies to understand the impact these considerations could make. When trying to maximise each site for the number of units achievable our addition of access locations resulted in approximately an 25% reduction in the number of units possible on those sites where access was limited or constrained. This varied on a site by site basis, with some sites achieving up to 67% less units.
The other key consideration for these more complex pieces of land is cost. This is a significant factor that we will delve into in more detail in our "Importance of Cost Data" blog post in collaboration with Turner & Townsend.
The potential of using these plots of land is evident to see and could play a key role in solving the housing crisis. The challenge comes in identifying their true possibilities for the capacity of each of the sites considering the various constraints that surround some of them.
The subsequent consideration is how to build these sites out to ensure suitable affordable housing is delivered while making them attractive to developers. An example is the Mayor of London’s Small Sites, Small Builders programme, which promotes the build out of small publicly owned land by small and medium sized builders. Larger scale funding schemes, such as the Building Council Homes for Londoners, will help to make land easier to develop and achieve the homes required. We believe that technology will be critical to prioritise and rapidly assess plots of land under any of these approaches, as demonstrated by our Mass Land Viability Study for TfL.
[1] Department for Communities and Local Government., (2017). Fixing our Broken Housing Market [online].