Image by: Adrià Goula

An opinion piece by Joe Giddings, UK Networks Lead, Built by Nature

This week saw the release of a succession of heavyweight reports from global scientific bodies warning that we are on the brink of catastrophic and irreversible global heating.

The United Nations have spelled out the challenge as clearly as possible. “Only an urgent, system-wide transformation across all sectors can avoid climate disaster,“ they said. That sentence is worth repeating over and over.

It can be easy to get lost in the details when in the business of delivering buildings. Necessarily so, buildings are complex beasts. But we need to keep sight of this bigger picture. So let’s pause for a second and reimagine our role as city makers and built environment professionals with this challenge in mind. How can we radically and urgently transform the way we make buildings and cities? How must we reshape the systems through which we make them?

This is about going beyond the concept of Net Zero. Beyond the notion of “less bad”. Beyond embodied carbon. Beyond reductions. Instead we must consider the much greater task humanity faces over the coming centuries, of fundamentally reshaping our economic systems and material flows so that human activity draws carbon out of the atmosphere and locks it into our built and natural environments, rather than extracting and releasing it.

The built environment and the forestry sectors alike have a huge role to play here, and an opportunity to play it together.

In Barcelona in early October a cross-sectoral movement was born with exactly this task in mind. The European Forest Institute (EFI) held their annual conference, which this year was focussed on the theme of “Bio-Cities”, or how our urban areas can work in closer harmony with nature. Concurrently, the Institute for Advanced Architecture of Catalonia (IAAC), with the support of the organisation I work for, Built By Nature, launched a national mass timber network to advance the uptake of structural engineered wood in construction with a playful mass timber takeover of Mies Van der Rohe’s Barcelona Pavilion. These two events intertwined, and architects and foresters shared a stage to spell out a big, bold and positive collective vision. This is a vision for how humanity can save itself and create a habitable planet for future generations.

The captivating Professor Hans Joachim Schellnhuber, atmospheric physicist, founder of the Potsdam Institute of Climatic Impact Research and now co-founder of a new organisation, Bauhaus Earth, opened the conference with a compelling narrative.

By 2020 more than 50% of the world’s population lived in cities, but by the end of the century that figure could rise to 80%. Newly built infrastructure to accommodate this growth could by the middle of this century already exceed the infrastructure built since the industrial revolution. Whilst urban densification through retrofit will accommodate some of this growth, particularly in European cities with relatively stable populations, vast numbers of new buildings and infrastructure are required. According to analysis by Marsh, our cities may need to accommodate an additional 2.5 bn people by 2050, with Asia & Africa accounting for 90% of this growth.

Now here humanity has a choice. Continued use of conventional structural materials, concrete and steel, could use between 35-60% of our remaining carbon budget to limit global heating to 2 degrees. However if we fundamentally reassess the value that our buildings can provide, and think of them instead as long term carbon stores, then they can provide a significant net positive impact. The Potsdam Institute’s research shows that by 2100, buildings could store 65 billion tonnes of CO2 through the use of engineered timber. In addition they calculated that the avoided emissions could amount to 106 billion tonnes. Add to this the uncalculated potential of other biobased construction materials such as straw, hemp and wood fibre. The overall picture is that through a wholesale shift to biobased materials, with timber leading the charge, our construction sector can switch roles and become a climate “hero”, as Schellnhuber puts it. This is a silver bullet.

The charismatic Spanish architect Vincente Guillart, head of IAAC and director of his own practice, tells a story of how the city has evolved over the past century and how we’re on the cusp of a new urban model. He denounces the “nightmares” of urban segregation, concrete structures and private cars. Ideas that have “destroyed” the world. What we must look ahead to now is a new revolution in the way that we make cities, a positive vision that we can all get behind. This vision is for a built environment that works hand in hand with nature, contributes to reforestation and leads to the restoration of natural habitats and ecosystems. We can no longer think of the built environment and nature as separate. As Guillart puts it, “the city of the future is a forest.”