The case against tall buildings in Bristol
19th March 2021
The city seems to have encouraged tall buildings – such as Castle Park View. Yet I believe this is the wrong policy for sustainability, for the city’s economy, and for our happiness. Changing course will cost nothing, but yield significant gains.
The science suggests that tall buildings use dramatically more energy than other buildings on an ongoing basis, in fact 100% more energy per square metre. This has been shown in research by Professor Philip Steadman (cited below), using a large data set of 612 UK office buildings, new and old, large and small, air-conditioned and naturally ventilated.
Carbon emissions per square metre of tall buildings are more than twice as large. Tall buildings in fact never use less energy, except in the case of one Foster building where the architect has effectively encased one tall building inside another, obviously a highly expensive undertaking. Tall buildings also use more “embodied energy”, i.e. energy consumed during construction – maybe as much as 60% more “embodied energy”.
Rab Bennetts of architects Bennetts Associates commented, “A tall building is far less efficient than a low-rise building for obvious reasons – heavier structure, more lifts and services, higher-performance cladding etc. – so it is much more difficult to reduce its carbon emissions.”
“Far more difficult, however, is the whole issue of embodied carbon, which is proven to be greater than the operational carbon during a building’s life. This is usually ignored by those who are saying their buildings are ‘zero carbon.’
“Most buildings that are trying to reach zero embodied carbon are reconciled to going only part of the way, as it is so difficult to get low emissions materials and transport into construction.
“There is therefore an established method of offsetting to deal with the remainder, which is costed. A tall building would find that the amount of offsetting is huge compared to something lower. ”
Contrary to common belief, tall buildings also make no contribution to densifying city centres and so reducing car use.
Tall buildings’ shadows tend to block neighbouring buildings’ light, so they need to occupy extra space. So the typical mid-rise building has the same Floor Space Index as a tall building (FSI = floor area, divided by land area used), i.e. tall buildings do not in practice provide extra density. Again, this has been suspected since the built structure diagrams by Cambridge professor Leslie Martin, dating back to the 1930s, but Professor Steadman’s recent research in London seems to confirm it.
Tall buildings are also significantly more expensive, so yield much less social and affordable housing.
The evidence is also clear that tall buildings cause unhappiness – they are associated with greater loneliness and more depression, are not optimal for parents and children, are associated with social relations that are more impersonal and where helping behaviour is less than in other housing forms, notes a survey by Robert Gifford (2007), which concludes: “the literature suggests that high-rises are less satisfactory than other housing forms for most people.’
What built forms add pleasure, encouraging sociability and happiness and improving mental health? The consultancy Create Streets has gathered evidence which points to the following list:
- Trees and green – but preferably green in smallish spaces, with private green areas, or areas shared among rather few people (e.g. a small park).
- Streets with no or only slow-moving motorised traffic.
- Streets with active facades rather than dead spaces.
- Symmetrical buildings, with detailing and decoration. Views of water.
- ‘Traditional’ rather than ‘modern’ building designs.
- Buildings with colour.
- Small squares rather than large squares.
- Green suburbs (though the stress of commuting can completely undo the associated increase in happiness).
- Mid-rise buildings rather than high-rise.
We have most of these in Bristol. Why we’re rushing to build tall is not clear. Let’s draw back from this course of action and try to build a city that works for the environment, for our future, and for our happiness.
- Planning officers should investigate which building types support the achievement of the One City Climate and Ecological strategies
- You can contribute your expertise to the charity Better Urbanism for Bristol (firstname.lastname@example.org)
- Expert views on high-rise Bristol, event by the Bristol Civic Society
- High Rise Buildings: Energy and Density
- If we care about sustainability, should we still be building super-tall skyscrapers? Lloyd Alter
- Energy use and height in office buildings Daniel Godoy-Shimizu, Philip Steadman, et al.
- The consequences of living in high-rise buildings Robert Gifford