The idea of a circular economy, where raw materials are recycled and reused, instead of being sent to landfill, has been slowly growing in popularity in built environment circles for many years.
The concept is particularly important when it comes to refurbishing or renovating existing buildings, but what about the redevelopment of parks and urban spaces?
Could a circular approach also be of benefit there, as well?
The director of the Carnegie Mellon University Scott Institute for Energy Innovation, Costa Samaras, said the prevalence of construction and demolition debris needs to be “front and centre” in the circular economy discussion, in an interview.
Samaras said between two and three billion tons of construction demolition debris are generated globally every year and so it is important to have systems in place to capture materials like concrete, which can be recycled but sometimes just go to landfill.
He also highlighted the need to look at water as an asset, rather than a waste product.
“As rainfall gets heavier, we also need to ensure our built environment and urban spaces can be areas where water can flow in a way that does not affect the people or the infrastructure or the environment,” he told me.
“We need to make sure that when water hits the land, it has an opportunity and path to go into the ground rather than onto the street,” Samaras added.
“A lot of the infrastructure we will build today will still be in service in the middle of the century and at the end of the century, and making sure it can perform at that point is a primary objective of good design and climate resilience.”
Sarah Dodge, a programme manager at the Ellen MacArthur Foundation, said the circular economy is about building prosperity for people and nature while living within planetary boundaries, in an interview.
Dodge added that it is important to keep materials in use wherever possible and take a site-based approach when developing or regenerating parks and urban spaces.
She cited the High Line public park in New York as a good example of adaptive reuse, reusing existing structures and adapting an existing space.
Dodge also mentioned Cuitláhuac park in Mexico City, built on top of a former landfill, which includes wetlands and lakes, reforested areas, sewage treatment works, and a rainwater collection system.
In addition, 27,295 species of plants have been added to the park, while 14% of the materials which make up this space are made from recycled plastic and construction and demolition waste.
“For urban design, the circular approach means starting with the land and assets we already have, instead of building somewhere new,” said Dodge.
“Then it’s about making the most of what’s already on site, and building in adaptability, resilience, and space for nature to regenerate,” she added.
“And our public parks are important to people’s everyday lives, which makes them powerful places to help people understand and connect with circularity.”
Another example of this circular approach has been the restoration of Crystal Palace Park in London.
HTA Design was appointed by Bromley Council and Crystal Palace Park Trust as lead consultant and landscape architect on the project.
The design team created a series of sustainable urban drainage features, such as swales and rain gardens at the bottom of the park to manage stormwater.
They also reused 7,500 tonnes of soil to re-profile the Italian Terraces, which saved an estimated 375 truck journeys to landfill sites.
Lighting columns in the park were repurposed, furniture was refurbished and a new visitor centre, designed by Tate + Co Architects, was built on an existing concrete slab footprint.
Natalia Roussou, landscape design director at HTA Design, said reusing materials was embedded in the “park’s DNA” after the original Crystal Palace was moved from Hyde Park to Sydenham Hill in the 1850s.
Roussou said their approach to regenerating the park was based on three principles: to restore, revitalise and reimagine by introducing a series of sustainable strategies to create a “resilient, biodiverse and adaptable landscape”.
HTA Design also took a circular approach when the Royal Parks commissioned it to create a garden that serves as a lasting tribute to Queen Elizabeth II in Regent’s Park.
The firm’s partner and head of landscape, James Lord said reusing concrete, gravel and steel on site, resulted in an estimated 80% reduction in embodied carbon when compared with typical practice.
Lord added they were able to take 1,000 cubic metres of surplus concrete from existing structures in the park and crush it into a fine mix, which was then blended with subsoil and green compost.
He said this created a free-draining, Mediterranean-like soil, which will support drought tolerant and biodiverse planting.
“Resources are finite and that applies to landscape, parks and the public realm as much as it does anywhere else,” he told me.
“The days of being able to assume you can dispose of resources and give them away are no longer with us.”
