When we plan for development, it’s expected that we test for daylight and sunlight and most models also test for overheating within the building, yet it seems we don’t consider the same factors when designing our streets. To a limited extent, we test for wind factors to avoid creating a canyon effect or dangerously windy corners, and we may test for flooding where there is a presumed surface water flood risk from rivers or storms. Yet, I feel the healthy streets assessment only allows for modest focus on the full impacts of climate change.
For those not in the know, the existing 10 healthy streets criteria are:
- Easy to Cross
- People Feel Safe
- Things to See and Do
- Places to Stop and Rest
- People Feel Relaxed
- Not Too Noisy
- Clean Air
- Shade and Shelter
Only the last 3 touch on climate change but only ‘shade and shelter’ considers the potential for excessive heat, and even then, it’s somewhat indirect.
There are two perception criteria within that list: people feel safe, and people feel relaxed. I’ve always felt that at least one of these was redundant because if one can’t feel safe then it’s unlikely that relaxation is possible, and the locations in which one feels safe but yet not relaxed are minimal.
As the UK gets increasingly hotter, I would propose the perception criteria are merged and a new one introduced: robust against climate change. This would give a focus on aspects such as:
- Quality and type of materials. Black asphalt retains much more heat than pale paving. Dark brickwork also retains and expels more heat compared to white cladding. Permeable paving assists in soakaway of rain.
- Presence of open water or SUDS
- Degree and quality of mature tree planting. Leafy streets tend to be much cooler at ground level as mature trees transpire during the day. Wide swathes of grass achieve relatively little in terms of cooling.
- Presence of excessive reflective materials – you may remember the ‘Walkie-Talkie’ building when first installed reflected sunlight fiercely enough to melt the paint on cars. Large glass facades can likewise make it hotter.
It’s true that many of the approaches to addressing noise and air quality also benefit in cooling our environment, but there’s a national habit (I feel) of failing to address the issue by name quickly enough. When we talk about this huge global issues, there’s always a struggle to see how at an individual professional level, anyone can make a difference – but we must start thinking in those terms and thinking holistically.
Inclusive, healthy places are of a reasonable temperature for the UK’s climate context, so as we masterplan, let’s include reducing urban heat in our thoughts. Global climate change is a bigger challenge than most of us, but we should at least put our monsters under the spotlight. If every design team had urban heat in the back of their mind, design changes accordingly, and if every local place could work to reduce urban temperatures, we may be able to make more of a difference.
by Sarah Chapman
