Britain faces a severe housing crisis in our major cities. From London to Edinburgh, a lack of new homes have driven up rents and house prices to extreme levels. This not only causes immense damage to the environment, human welfare, jobs, growth and public services, but is a moral failing – with people stuck in unaffordable, unsuitable accommodation. The only solution to this is to build more homes.
At the same time, we are facing significant anthropogenic climate change, and we need to decarbonise large swathes of our lives to meet our national and international commitments to net zero. Reorganising our built environment to increase density can help us make progress on this while working to end the housing crisis and grow the economy. Recent work from Green Alliance has compiled evidence that building up in cities can deliver more homes and reduce our carbon footprint.
That higher densities let us build more homes is obvious: more people are able to live in the eight storey mansion blocks of Marylebone than the detached houses of Acton. What’s less well appreciated is the array of other benefits that this brings. Dense, mixed-use urban areas support ‘active travel’ (walking, cycling etc) as residents are close to amenities removing the need to drive. People who live in dense cities are easier to serve with frequent public transport, replacing polluting commutes with an efficient bus or train trip. Running these services in low-density areas is much harder to justify as serving the same number of people requires many more lines spread thinly over a larger area.
It’s not just transport emissions that are lower when we build denser. Domestic energy consumption also falls as density increases. Purpose built flats have just a third the annual carbon emissions as a detached house. The shared walls reduce heat loss whilst it’s much easier to insulate new buildings than retrofit old ones.
The issue of retrofit vs rebuild is complex. Commentators often point to the ‘embodied carbon’, the emissions involved in creating the materials for the new block and building it. But analysis from Green Alliance confirms that when adding new homes, rebuilding at higher densities often actually leads to lower carbon emissions overall. The case study in the chart below compares two ways of delivering 300 homes around an existing transport node. In the ‘demolish and densify’ case, 50 existing homes are demolished, replaced with 300 flats over the same area. In the ‘no demolition’ case, the 50 homes are joined by 250 new homes. The demolish and densify option uses about the same amount of carbon for the demolition and construction work as the ‘no demolition’ case, but the higher density radically reduces residents’ energy needs for heating and especially for transport. Over the 60 years this saves 3,000 tCO2e. This is not to mention the significantly reduced land use – 17 hectares (42 acres) of greenfield land is left untouched – potentially preserving swathes of nature for future generations.
Policies like tenant-led estate renewal demonstrate that we can densify urban areas, improve the quality of life of residents, and create low-carbon housing. YIMBY Alliance pushes for policies for more intensive land use with the support of residents, to enable us to unlock these sustainable urban environments. We believe that ensuring that communities receive a fair share of the benefits of development and empowering them to say yes can help mitigate not just the housing crisis, but also the urgent challenge of our climate.
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