Plants in cities contribute to urban greening in many ways, from providing shade and humidity and absorbing surface water to providing barriers to road noise and pollution. As our climate changes, we may be increasingly exposed to more extreme weather events such as heatwaves and droughts, but also severe storms and floods. By increasing the amount of urban planting and making nature part of the city environment, the worst impacts of the weather can be counteracted. 

While hard surfaces can only absorb or reflect heat, planted surfaces can cool the air above them and trees provide shade. Equally, flood water has nowhere to go on a hard surface but into the drains which can swiftly become overwhelmed. By comparison, a planted surface allows the water to soak away more slowly and can help to prevent flash flooding. Inside buildings, plants have a cooling and humidifying impact on their surroundings and have been shown to be able to absorb some airborne pollutants.  

The Energy Efficient Cities initiative (EECi) at the University of Cambridge Department of Engineering has at its heart the ambition to understand how we can reduce our energy demand and environmental impact in towns and cities. One aspect of our mission is looking at the importance of plants in the urban setting, both inside and outside buildings.  

At the EECi, we are interested in how we can use our understanding of how buildings are operated in cities to learn about how to make the best use of planting designs. We are particularly interested in urban farming and the way in which derelict spaces might be used to produce food and at the same time benefit the environment. 

Increasing urban populations mean that larger quantities of food have to be brought into the city on a daily basis. This inevitably leads to more food miles and a higher carbon footprint. Producing fresh food in the heart of the city can help to address this challenge and brings other benefits in terms of job creation, reduction of pollution and less food waste. Encouraging plant growth and food production in our schools can help children to better understand where their food comes from. Including communal growing spaces such as allotments or gardens in urban re-generation projects can have positive physical and mental health benefits too.

EECi, in collaboration with the Centre for Smart Infrastructure and Construction, have been working to help improve the efficiency, productivity and profitability of urban farming in collaboration with the world’s first underground farm, Growing Underground.

Located 33 metres below Clapham High Street in London, this farm has been developed in former World War II air raid shelters. While the intention was to join the shelters into the London Underground system in the post-war period, this never happened and the tunnels sat unused for decades. In 2015, co-founders Richard Ballard and Steve Dring started to develop the site for food production. Now the fully productive farm grows micro salads, such as pea-shoots, basil, coriander, pink radish and salad rocket, which are delivered to New Covent Garden Market less than a mile away for distribution to restaurants and supermarkets across London.