Integrating trees, plants, and water features into the built environment is no longer just an aesthetic choice, it has become a necessity as the UK endeavours to adapt to a changing climate which is becoming more evident as we experience yet another summer of extreme heat. Nature-based solutions such as trees are critical to climate resilience that can help prevent our towns and cities from overheating during the hot summer months while simultaneously helping to manage the UK’s growing flood risks during the rainy season.
The Concrete Trap: Why the UK Must Adapt
Decades of developing “grey infrastructure” comprising various types of impermeable surfaces such as roads, sidewalks, buildings, etc. have created heat-trapping urban heat islands which also creates excessive run-offs during rain events which often time overwhelm the old sewer systems. To counteract this, we need to have a multi-faceted approach in developing our built environment where we combine expertise from various disciplines to come up with creative and innovative ways to transform our towns and cities into thriving and happy communities comprising an oasis of “green infrastructure”.
The Science of Urban Cooling and Water Management
Vegetation cools the environment through evapotranspiration, a natural process where plants release water vapor that lowers surrounding air temperatures by several degrees. Furthermore, integrating Sustainable Drainage Systems (SuDS)—such as permeable paving, raingardens, and green roofs—will allow us to construct “sponge cities”. Instead of water immediately flooding the stormwater network, SuDS intercept and attenuate rainwater naturally, filtering it while sustaining urban plant life.
Lessons from Hotter European Climates
Mainland Europe has long faced severe summer temperatures and has successfully pioneered cutting-edge engineering techniques to combat them. We can learn from and adapt some of concepts to devise some strategies for the UK:
- Milan, Italy: Famous for the Bosco Verticale (Vertical Forest), Milan showcases how structural engineers and botanists can collaborate. These residential towers incorporate thousands of trees and shrubs onto cantilevered balconies. The greenery acts as a natural air filter, absorbs CO2 and creates a shaded microclimate that prevents building interiors from overheating.
- Stuttgart, Germany: Stuttgart has pioneered a large-scale “sponge city” and green roof policies to tackle the urban heat island effect. The city enforces strict building guidelines requiring vegetated roofs, which naturally reduce ambient air temperatures and mitigate stormwater runoff.
- Malmö & Copenhagen: Scandinavian cities routinely utilize open water features, canals, and bioswales integrated seamlessly into their streetscapes. These elements retain stormwater while providing passive evaporative cooling during heatwaves.
Engineering urban natural systems for the future
To implement these changes in the UK, we must creatively and strategically integrate landscape architecture within the planning and development of all infrastructure. Furthermore, once the plants, vegetation and other natural features are integrated within the hard infrastructure they must be maintained to not only provide the desired functionality of rainwater attenuation, air filtration and reduction of the micro-climate temperature but to also engender a sense of place and comfort for residents.
There are some companies that are working to develop innovative ways to integrate trees and vegetation into urban spaces through biophilic design, which is the practice of integrating natural elements, material and patterns into the built environments to reconnect people with nature. One such company, headquartered in London, Alive Labs has extended the green wall concept, to develop a green cladding system, where moss is intricately grown on concrete panels that can be attached externally on a building facade or installed internally. Not only can the moss be artistically grown on the panels to create stunning architectural designs to enhance the building exterior, but it provides vital functionally for the building microclimate by the following functions:
- Air Purification: The moss captures particulate matter (such as PM10 and PM2.5) and absorbs carbon dioxide.
- Passive Cooling: The vegetation naturally mitigates the urban heat island effect by cooling building surfaces through evaporation.
Additionally, because the moss extracts moisture and nutrients directly from the ambient air and rain, it reduces the maintenance requirements needed compared to traditional green ‘living’ walls.
As we work to adapt to climate change, more innovative systems such as the moss-based living wall system developed by Alive Labs will need to be integrated within the built environment to transform our infrastructure into functional as well as exciting, pleasant and harmonious places to live, work and play.
Please read about the great work being carried out by Alive Labs, on their website outlined by the tab below.