A group of built environment enthusiasts joined architect Julie-Ann Futcher in Finsbury Square on the morning of Saturday, May 16th for a walking tour exploring the urban climate of the City of London. Julie-Ann is a co-founder of Urban Generation, which focuses on educating built environment professionals on how to better adapt to and mitigate the effects of urban climate change.
The tour lasted approximately 90 minutes, covering well-known locations such as Broadgate, The Heron Tower, The Gherkin, The Cheesegrater and The Walkie-Talkie, with a concluding stop at the riverside by Old Billingsgate, before the group retired to a nearby pub to continue the conversation.
Julie-Ann emphasised a number of issues which are not being taken into account in a sufficient manner during the planning and design process.
Among the issues raised were:
- There is a direct link between buildings and their urban settings, from an energy management perspective. This relationship extends beyond each building’s envelope.
- The heating and cooling of buildings largely depend on their orientation towards the sun and their use throughout the day.
- The ‘urban heat island’ term is a simplification – In reality, there are multiple, disparate ‘heat islands’ within the urban area.
- The weather files used for planning and design do not take into account the use of the buildings (i.e. no differentiation between commercial and residential)
- Heat and pollution behave in a similar manner and the larger the height to width ratio of a particular street, the slower the dissipation of this heat/pollution (sometimes not until early the following morning). The urban canyon of Ropemaker Street / Milton Court was a prime example of where pollution can be trapped for long periods of time. The street also receives minimal sunlight due to the height of the buildings (City Point, and The Heron) on its southern side.
- Nocturnal air temperatures in the City of London can be up to 7 degrees higher than the nearest weather station readings at Heathrow.
- Urban climate has a much greater impact on smaller buildings.
- The Heron Tower’s South-facing photovoltaic cells contribute 2.5% of the building’s energy needs. However, the shadow which the forthcoming tower at 100 Bishopsgate will cast on the southern facade of the Heron Tower could, in theory, contribute to a 10% increase in The Heron Tower’s energy efficiency, due to the reduced need for cooling (The reality is different due to the orientation of The Heron Tower’s office floors, however the point that buildings can affect the energy profile of their surrounding neighbours still stands).
- The Buckminster Fuller-inspired geodesic design of The Gherkin allowed for energy efficiency through form – However, the air circulation system had to be curtailed as it generated a negative impact in terms of acoustic interference between floors. The resulting noise mitigation has hindered the air circulation system from achieving its original purpose, suggesting a negative correlation between energy efficiency and acoustics.
- The shape of a building affects not only its own energy management but that of surrounding buildings as well. This has an impact on the ground level microclimate, as is witnessed by the windy gap between the Cheesegrater and the Aviva Tower. The Cheesegrater’s cantilevered canopy helps to mitigate gusts travelling to ground level along the tapered southern facade, but can also hinder traffic pollution from dissipating upwards.
- The ‘right to light’ of buildings has proved a controversial topic, and led to the compulsory purchase of properties surrounding The Walkie-Talkie, in the public interest. Similarly, the loss of light in the Boundary Estate due to the forthcoming Bishopsgate Goods Yard is of concern.
- The infamy of The Walkie Talkie’s concave southern facade was discussed as the group passed by the store fronts of Eastcheap, where blistering and scorch marks from August 2013 are still visible.
- There is currently no way of evaluating building form in terms of energy efficiency
- City Hall is an efficient design, in stark contrast to the energy ratings of its contemporaries at the More London development.
- The circulation of fresh air as it enters London from the Thames Estuary is curtailed by the lack of gaps between buildings along the foreshore.
We’d like to thank Julie-Ann for a very informative event and look forward to collaborating with her in the future.