Climate change is becoming more and more real every day: all over the world, we are witnessing a clear increase in climate disasters. Moreover, the latest IPCC report warns us of possible “tipping points” from which the climate transition could become not gradual, but sudden and irrevocable.
Hélène Cartier is a speaker at the new LifeCycles festival, taking place in Ghent 28 to 30 September 2022.
Spread across 3 days and 3 stages LifeCycles will gather over 40 leading speakers, discussing the future of out cities, architecture and environment. More info and tickets on www.lifecycles.be
Over the past decade, the progress made to keep global heating below the 1.5°C goal of the Paris Agreement has been poor. The leading climate scientists are now clear: the 2020s will be a make-or-break decade for the survival of our environment. The global emissions must peak before 2025 and be reduced 43% by 2030.
It is therefore an absolute priority to act and to cut emissions from the sectors most responsible for the climate crisis. The built environment industry has especially a huge responsibility: buildings account for nearly 50% of annual global CO2 emissions, and the global building floor area is expected to double by 2060, which represents the equivalent of adding an entire New York City to the world, every month, for 40 years.
It is urgent to decarbonize buildings
Action to decarbonize new and existing buildings – by making them more efficient so they use less energy and by cleaning up the energy that they do use - are vital. Building operations are indeed responsible for nearly 30% of annual global CO2 emissions.
It is also key to minimize embodied carbon from construction. Embodied carbon has been under-estimated in the past. They are responsible for approximately an additional 20% of total emissions, and they represent an important leverage to rapidly reduce global GHG emissions. Indeed, unlike operational emissions that are spread over the lifetime of a building and can be reduced over time with building and energy system upgrades, embodied carbon generates an irreversible peak of emissions at the very beginning of a project.
To reduce embodied emissions, it is crucial to slow down construction where possible by optimizing the use of the existing buildings – For example, a recent study has shown that in France, the proportion of vacant housing rises to 8.3% in 2021. This represents nearly 3 million housing units, compared to 1.85 million in 1982.
It is also key to promote adaptive reuse projects and prioritize retrofitting building to limit the vicious cycle of ‘demolition/reconstruction’. In that sense, when new construction is needed, it is key to build for the long term – In fact, many buildings that are demolished do not have structural problems. In most cases, their demolition is due to their design and layout that do not fit anymore with the needs and demands. Using modularity/flexible design to enable future adaptation of the building and expand its lifespan, is therefore of great importance.
Finally, it is crucial to use materials efficiently and to consider construction materials with lower emissions such as timber and other bio-based materials. Across the world, several pioneer projects that tackle embodied carbon emissions are being implemented. The Porte Montreuil project, winner of the C40 Reinventing Cities competition in Paris, is a great example. This strategic site, extending over 35 ha, will be the first Net zero neighbourhood of the City. The constructions will be made of local, bio-sourced materials, and 100% of the buildings will be reversible allowing the uses to change and the spaces to be transformed over the time, thus minimizing the need of demolition in the future.
Beyond buildings, it is a new model of urban development that is needed.
Architects, urban planners, developers, engineers - don’t just build or transform individual buildings or blocks, they build a place where people will live. In that sense, they also contribute to shaping the overall model of city.
The latest IPCC report highlights the importance of integrated urban planning to reduce emissions. It says that urban emissions can be cut by around 25% with more compact, mixed uses and resource-efficient cities.
Urban planning is not a separate emissions sector, but a cross-cutting enabler of emissions reductions and increased resilience. Once built the urban fabric (streets, buildings, infrastructure as well as the mix of uses and people) is very slow to changes. Getting urban development right is therefore crucial to ensuring emissions reductions to happen in key sectors like transportation, buildings as well as to reducing vulnerabilities to climate risks and social divides.
But what is a good model of urban development?
- This is one that is polycentric and made of multiple ‘complete neighbourhoods’ that are compact, that integrate a mix of people and uses and the essential amenities and services as promoted in the 15 minute city model.
- This is one that promotes people-centred streets and mobility, by reclaiming city spaces from private vehicles and designing public space that can act as the ‘living room of the neighbourhood” — a place where people can come together.
- This is one where every neighbourhood is connected through quality public transport as well as digital infrastructures that are essential to avoiding unnecessary travel and enabling more flexible working practices.
- This is a one that harnesses urban nature to improve climate resilience and air quality, as well as foster physical and mental wellbeing.
- This is finally one that equips and empowers communities to adopt a low-emissions life by providing local facilities, such as compost for organic waste, bike parking, zero-waste stores, ‘return and recycle’ hubs and other shared services.
Many of these principles build on the 15-minute city concept, on which the last IPCC report place a particular emphasis, and which allows everyone, in every neighbourhood, to meet most of their everyday needs within a short walk or bike ride of their home.
These principles might seem like good sense, but they are in fact in sharp contrast to urban-planning paradigms that have dominated the past century, which have seen a monocentric urban development, and a specialization of city neighbourhoods: Residential areas separated from businesses districts, commercial areas and industry, and all of them connected by transport infrastructure that was mainly car-oriented. This situation led to long commutes, poor air quality and a lack of amenities in many neighbourhoods, exacerbating feelings of isolation and inequity as well as unsustainable lifestyles.
The past two years have witnessed a surge of interest in this 15-minute city concept, as the disruption of the pandemic and the development of hybrid working emphasized the importance of the hyper-local environment to support quality of life and a more sustainable lifestyle. Many cities across the world have embraced this model. Leading examples include Paris’ 15-Minute City, Barcelona’s Superblock, Portland’s Complete Neighbourhoods, Melbourne’s 20 Minute Neighbourhoods, as well as Bogotá’s Barrios Vitales.
To tackle the climate crisis, cities and the built environment sector must collaborate to harness such models of buildings and urban development. Ones that are not only low-carbon but also resilient and thriving for the local community so that they can be widely replicated, especially in rapidly growing cities.
As urbanization is growing, cities are our best chance to fight climate change.
Urban lifestyle is indeed the most sustainable because urban residents have smaller homes – which means fewer buildings emission, and they can have more easy access to the infrastructures, services and facilities that make a sustainable lifestyle possible.