Could our streets become too hot to handle?

The current global lockdown has highlighted the importance of the public realm to city dwellers.

La Puerta del Sol, Madrid

Public spaces have a paramount role in creating lively, safe, sustainable and healthy cities and are especially important to those who have no outdoor space of their own.  Public spaces provide health and wellbeing benefits by offering somewhere to take time out, be active, connect with others or just watch the world go by.

But as the world warms up, public spaces could become increasingly uncomfortable and under used. Places that previously had a vibrant street life could become quiet.  For example, by 2050, Madrid could experience conditions resulting in very strong or extreme heat stress for an additional 400 hours a year, equivalent to 1/20th of a year (see Figure 1).

Figure 1: Comparison of potential hours of heat stress in Madrid today (2020) and 2050

However, the impact of extended periods of extreme heat could result in us exacerbating climate change. For example, many cities see increasing active travel as a key way of reducing emissions, with transport often accounting for over a quarter of a city’s direct emissions; but as temperatures rise, if private cars are increasingly used in preference to walking and cycling then so will emissions.

During the pandemic, cities around the world are repurposing road space to allow more room for pedestrians and cyclists. It would be a shame to lose any gains to active travel because conditions outside become too much to bear.

There are also issues of equity to consider. For example, low income neighbourhoods in the USA have been found to experience the urban heat island effect more, and for people who cannot afford air conditioning, access to good quality, comfortable outdoor space can provide respite from overly hot homes.

In response to these challenges, we need to understand the types and locations of places at risk, in order to draw the most impactful and relevant types of interventions. Buro Happold has been developing rapid analytical tools that can help achieve this understanding. These include:

  1. Using current climate data and future projections to assess whether a city is at risk of experiencing significantly longer periods of heat stress creating conditions
  2. Using lidar data to model existing public spaces in cities to understand whether the existing architecture is a help or hindrance in maintaining comfort
  3. Rapidly testing the impact of different intervention types of the comfort conditions throughout a day. For example, it may make sense to focus effort on those interventions that have the biggest impacts during a city’s rush hour (see Figure 2).
Figure 2: Results of rapid assessment of impact of different intervention types on comfort

Equally important to the analysis is to develop interventions that are modular and multi-functional and can unlock improvements in accessibility and affordability e.g. providing places to reflect, people watch and experience city life, just as much as shelter. We have been working with a range of urban designers and landscape architects including CBT Architects to develop solutions for a wide range projects in the UAE as part of ambitions to improve liveability.

Here lies the interesting design challenge – to create solutions that bring joy as well as respite from an increasingly harsh climate. We at Buro Happold can’t solve this challenge alone, so please get in touch if you’d like to develop something together for your city.

Figure 3: Model of comfort impact of addition of shading for pedestrians waiting at an intersection crossing

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