Nature in the city: highlights from the CIRIA green infrastructure walk in London

Stop 1: Elephant Park Neighbourhood and Green Roof

Arcadis are delighted to Chair CIRIA’s Biodiversity Community of Practice and as part of that group, I had the opportunity to attend their Biodiversity CoP Green Infrastructure walk led by CIRIA CoP manager Adrien Baudrimont, around London with a group of ecology and sustainability professionals from different backgrounds and organisations. Our first stop was Elephant Park, an urban neighbourhood designed with a focus on integrating green spaces. This neighbourhood is an example of how including nature within city environments can create a habitat for wildlife, including birds, insects, and bats while delivering a thriving business and community environment. Despite its proximity to a busy tube station, the neighbourhood felt calm and pleasant with its trees and gardens amidst the urban environment.

We also visited a private residential building that had implemented a green roof years ago. This roof is covered with so many plant species, making it visually appealing for residents in surrounding high-rises and also supporting a robust ecosystem. Monitoring has shown the presence of bat species and invertebrates using the roof. This green roof is a low-maintenance system, with plant species allowed to thrive naturally with minimal intervention. It even includes photovoltaic panels, further enhancing the sustainability benefits of the roof.

It was inspiring to see how this green roof boosts urban biodiversity, improves habitat connectivity and helps species thrive in the area. Additionally, roofs such as these can help mitigate the urban heat island effect and create a more visually attractive view for residents. Thanks to Morgan Taylor and Jo Ferguson from Greengage for arranging access and telling us about the roof’s evolution.

Stop 2: Blackfriars Living Construction Wall

Our next stop was at the living wall by Vertical Meadows at Blackfriars. This beautiful green wall, integrated into the construction hoarding of a Lendlease project, contains over 25 different plant species growing on a recycled felt medium. It uses a drip pipeline irrigation system which can be controlled remotely. The wall is maintained without sprays or pest control and can also be monitored remotely.

The living wall has a design life of two to three years, after which time it can be relocated and reused on new construction projects. Living walls significantly enhance

the environment around construction sites, mitigating negative visual impacts and making the area more pleasant for people passing by. This innovative approach to integrating green space into construction projects is something I would love to see more widely adopted in urban areas where construction is widespread and frequent.

I found the thoughtfulness in making these walls sustainable particularly impressive. They use recycled or biodegradable materials in the substrate to reduce their embodied impact and include planning for end-of-life repurposing. Thank you Alistair from Vertical Meadows, for showcasing this innovative approach to integrating green spaces in construction projects.

Stop 3: Marylebone Low Emission Neighbourhood SuDS

In Marylebone, we explored examples of Sustainable Drainage Systems (SuDS) as an alternative to conventional concrete drainage systems. SuDS manage rainwater while bringing additional green space into the neighbourhood. They reduce flood risk, improve visual amenity, and support biodiversity.

The SuDS in Marylebone have been installed, since 2016, at existing gully locations,

where they slow down surface water flow and allow infiltration before entering the existing drainage system. They included a variety of plantings including trees, grasses and perennials. Several different designs of SuDS were used the neighbourhood, each with a unique appearance and purpose. Some of these designs have been implemented more effectively than others which was directly reflected in the health of the SuDS plant community and therefore the performance of the SuDS.

My colleague Martina Girvan from Arcadis explained some of the additional ecosystem services offered by SuDS such as improved amenity, nutrient absorption and improved safety for road users. She explained that when these additional services are considered in cost-benefits analysis of these systems, benefit-cost ratios of up to 10:1 have been demonstrated, highlighting the advantage of SuDS as an alternative to or in addition to conventional drainage systems. Thank you Martina, Chair of the CoP, for you insights on the advantages of SuDS in urban environments.

Stop 4: Carnaby Street Living Walls and Green Roofs

Our final stop was at Carnaby Street, where we saw living walls installed on commercial developments in high retail value spaces. These walls, with diverse plantings including pollinator-friendly plants, enhance the area's visual appeal and support urban biodiversity. They also help reduce the urban heat island effect and improve air quality.

These walls and roofs demonstrate that nature can thrive in urban centres, even in areas lacking space for conventional plantings like Carnaby Street. Seeing many bees using the walls was a highlight for me. Thank you to Angus Cunningham and Santhosh Johnfrom Scotscape for showing us these examples of your successful living walls.

Key Takeaways and Reflections

This walk highlighted the transformative potential of green infrastructure in urban environments. By integrating green spaces, we can enhance biodiversity, improve visual amenity, manage stormwater, and boost urban resilience. In cities like London, retrofitting systems like SuDS and green roofs provides many benefits, making our urban spaces more liveable and sustainable.

Integrating green infrastructure elements into urban design makes sense as these solutions deliver essential ecosystem services, such as building resilience to the effects of climate change and improving biodiversity. Designing with nature instead of against it builds resilience in our urban environments, creating more liveable and sustainable cities.

I hope this summary of London's green infrastructure inspires others to consider similar initiatives in their urban projects. I am confident that by integrating these solutions we can create greener, more resilient cities for the future.