How can cities build resilience to thrive in a rapidly heating world?
We live amongst multiple and simultaneous climate crises, and one of the most impactful consequences of the change in our climate is the increase in record-breaking heat.
Urban heat is a particular problem, with the kind of infrastructure and systems that—almost—seem designed to trap heat. And this infrastructure in turn is affected by extreme heat, causing increased energy consumption/strain on power grids, degradation of materials, and increases in water demand.
Why is this important to our industry? The built environment has a critical role to play because it affects so much of our lives—and its influence is clearly felt during elevated temperatures.
Focusing in on cities and the experience of living within them during a time of climate emergency reveals some alarming trends. The physical and wellbeing impacts on humans of this heat should not be underestimated. Beyond the obvious thermal comfort considerations—very few people enjoy living through a rapidly intensifying heatwaves—heat can be deadly. So, how did we get to the situation where urban living can feel so hot?
Urban heat islands
Development patterns in urban areas exacerbate and amplify heat. Peaks of temperatures and heat waves are more keenly felt in cities, with urban areas experiencing significantly higher temperatures than their surrounding rural areas. This is known as an urban heat island.
Many things feed into the creation of an urban heat island, and they are almost all down to human activities and the wider structures and systems of the built environment. Heat itself is generated by human activities like transportation and energy creation/consumption. Surfaces like asphalt, concrete and metals absorb, trap and retain heat. Cities by their very nature have little of the green planting or natural landscapes that rural areas enjoy. This all adds up, and means living through extreme heat in an urban space can be challenging and even dangerous.
The impact of the climate emergency on how we live in cities in undeniable. How, then, can we adapt our behaviours and assets to create the most happy and healthy communities possible? How can we live alongside the extreme heat we are increasingly subject to? There are multiple considerations, both at building level and citywide/urban planning level. How we respond to this challenge is multi-faceted, and must always be holistic, looking at the wider picture and how different interventions interact.
What can we do to live in rapidly heating cities?
Sabrina Bornstein is a principal in our Los Angeles office and is climate action and resilience lead for US Advisory.
She said, “There are a number of physical urban heat island mitigation strategies in cities – think things like cool pavements, cool roofs, tree planting and park areas, and more permeable/less grey surfaces. Passive design choices apply as much in the urban public realm as they do to individual buildings.
“I’m especially interested in the public realm and public experience in areas like sidewalks. For example, I’m in LA, and something that has received attention recently is the idea of climate resilient bus shelters, to ensure people have shade access while they are waiting for public transit. Similar is the idea of ‘cool corridors’ for streets that can provide shade and connect pedestrians to cool resources, bringing a lot of these ideas together.”
There has to be a degree of out-of-the box thinking when it comes to supporting people to deal with heat in cities. Sabrina said, “We need to support indoor thermal comfort too, in addition to outside. Some cities are considering what the maximum indoor temperature should be and requiring that buildings provide a level of indoor thermal comfort and safety to residents. As with many problems, considering organised networks and systems that can respond to heatwaves is important.
“I feel there is room for innovation around access to cooling resources; can cities partner with museums or movie theatres to allow free or discounted entry during heatwaves? Should we prioritise connecting our public transit to cool resources to help move people to those places during extreme heat?”
Multi-disciplinary efforts to break up silos
Buro Happold recognise decarbonisation and net zero as a way to reduce the impact of the built environment on the climate and to propose solutions to the problems the climate crisis is causing. Our own routemap to net zero is a central part of how we operate and how we will achieve challenging targets. This is necessary mitigation. But resilience and adaptation remain as critically important. Those working in the built environment must understand the importance of looking at the whole problem holistically, looking at design and solutions that provide multi-benefits.
There are all the physical interventions discussed above, but there must also be work undertaken to understand the vulnerability of our cities, assets, infrastructure, natural environments and communities.
For example, Buro Happold worked with the city of Los Angeles to develop a climate vulnerability assessment (CVA), assessing the populations that were vulnerable due to factors such as age, income level or pre-existing health conditions, as well as hazards to the physical infrastructure and the cascading impacts that occur when these infrastructure systems are disrupted.
For Buro Happold, looking at this holistically means offering services stretching from micro-climate analysis, climate and/or heat vulnerability assessments, thermal comfort modelling, community engagement leading to specific heat action plans (such as for Burscheid, a town in Germany that increasingly felt the effects of urban heat), as well as building level intervention and passive design choices.
The uneven impacts of extreme heat
There is an equity discussion at the heart of this: not everyone experiences the impact of urban heat in the same way. Those who are the most vulnerable are nearly always those who have the least agency in protecting themselves from the impact of the climate emergency and of heatwaves.
Access to thermal comfort or adaptations like air conditioning can differ hugely between different social, economic and age groups, and extreme heat impacts vulnerable people the most. Interventions at a building, city or policy/systems level to manage urban heat must consider this.
Hear more from Buro Happold experts on how we can live alongside extreme heat in a rapidly warming world.