On a stiflingly hot and dusty morning at the height of the summer’s third heatwave, traffic thunders down the A12 arterial route through east London. A high, red-brick wall rises by the road. What few passersby will realise is that this ivy-topped wall shelters an urban oasis, within which sits an unprecedented sustainable project.

The world’s first “community-powered” sauna – heated by food waste from residents of the neighbouring housing estate – is set to open here.

R-Urban, a community powered sauna and allotment in Tower Hamlets. Photograph: Graeme Robertson/The Guardian

Scraps from the kitchens of residents on the Teviot estate in Poplar, will be processed in a local-scale anaerobic digester – another first for the UK – to produce methane gas to power the sauna. It is still in its testing phase and full operation will launch later in the year.

The completely circular design is just one part of R-Urban Poplar, a civic space and “living lab” where members of the community are invited to experiment with ways of taking charge of their own food supply, while adapting to the climate crisis.

Andy Belfield, an architect from the R-Urban Poplar team, says those behind the project believe it is the UK’s – and the world’s – first food waste powered community sauna.

The Guardian visited the project at the height of last week’s heatwave. Nine years ago, the site was an unused car park and empty garages. Now, butterflies flutter around leaves and flowers in raised, no-dig beds. Micro-allotments and communal growing spaces offer opportunities for local people to grown herbs, courgettes, potatoes and passion flowers.

But R-Urban Poplar is more ambitious than just a community garden. It is an “ecology hub”, where workers and local residents are prototyping circular urban farming, mushroom-growing and restore-and-repair services. Wild spaces encourage pollinators. There is a community kitchen and classroom, a workshop and a tool library, even a mushroom farm.

Its designers and backers see it as a tentative vision of a society that can thrive in spite of the accelerating disaster of climate breakdown.

R-Urban helps cities bounce back from challenges by having residents run local facilities that support each other. Photograph: Graeme Robertson/The Guardian

“That’s why this site is particularly interesting,” says Elle McAll from the Women’s Environmental Network (Wen), which for the past five years has helped fund R-Urban and coordinate its work with similar projects in the local area.

“It’s combining the technology and the technical side with the community building, the community side. Addressing the climate crisis isn’t about just those technical solutions in isolation. Sites like this really show the possibility of bringing those things together.”

R-Urban Poplar is one of 26 sites that have been part of a project led by Wen to embed an environmentally sustainable, socially just and community-led food system across Tower Hamlets, one of London’s most-deprived boroughs.

The allotment at R-Urban Poplar. Photograph: Graeme Robertson/The Guardian

Outdoor space is a rare luxury in Tower Hamlets, where about four in five households live in flats, and four in 10 families live in poverty. The borough has the UK’s highest population density, as well as high levels of air pollution.

“The whole thing really has been about how can we reimagine our local food system so it really does genuinely benefit local communities,” says McAll.

At a second Wen-supported site on the Limborough estate, a few minutes’ walk away from R-Urban, Toyoba Chowdhuri stands over her micro-allotment and lists the vegetables she is growing there. Growing on the plot, just a few square feet in size, are aubergines, courgettes, black chillies, malabar spinach and snake gourds.

“I’m living in Commercial Road. I haven’t got any [outside space] there,” says Chowdhuri. City life severs the connection to the land she had growing up in rural Bangladesh; her plot at the Limborough food hub restores it.

The lengths to which Chowdhuri goes to access the site are testament to how important it is for her. “I need two buses to come, and I come morning and evening every day,” she says.

Food provides something fundamental to organise around, building networks and communities that are ready to tackle wider problems, says McAll. Like R-Urban Poplar, the Limborough hub also includes a communal kitchen and eating space. Those give people a reason and spaces to connect.

“Food is something that everybody needs but also has deep emotional connection to memories,” says McAll. “It represents so much. It’s such a simple, unifying thing that can be a starting point for a lot of conversations.”

The issue at the heart of these projects is sustainability. At Limborough, the site is made available for use by the estate’s landlord, Poplar Harca. Every Wednesday, it hosts a food market, distributing cut-price organic produce – sometimes sourced from local growers – to the local community.

Rokiah Yaman: ‘The community sauna is a brilliant way of of really making the most value out of what we’re doing.’ Photograph: Graeme Robertson/The Guardian

For R-Urban Poplar, the sauna – a collaborative project by R-Urban, Mad Leap and Community Sauna Baths – will be pivotal. “What we can see from the modelling is that for food growing you have to do it at a certain scale to make it really economical,” says Rokiah Yaman of Mad Leap, who is masterminding the site’s anaerobic digester.

“But actually something like the community sauna is a brilliant way of of really making the most value out of what we’re doing. If you heat a sauna and then you charge for those sauna spaces and you have multiple sessions a day with 10 people in the session, that makes a big difference.”