Better design and reuse of buildings are crucial to cutting their carbon impact, writes Ellen MacArthur Foundation’s Tansy Robertson-Fall
Solving the climate crisis may be increasingly at the forefront of government, business, industry, and NGO minds, but there remains a disconnect between this and the way the built environment, and the construction industry, are designed. The Climate Action Pathway for Industry 2021 report, released by the UNFCCC, emphasises the need for a more socially responsible and environmentally sustainable industrial system. A plan that not only benefits the businesses involved, but arguably even more significantly, supports the reduction of greenhouse gas (GHG) emissions.
Much policy and media focus are targeted on the transition from fossil fuels to renewable energy and energy efficiency in order to reduce GHG emissions, but if the emphasis remains on energy alone it won’t be enough to tackle the climate crisis. Even if the transition to more renewable energy sources is achieved, there remains 45 per cent of GHG emissions that currently come from how we make and use products, and how we produce food.
A circular approach
The circular economy provides a globally applicable framework to galvanize action under its three guiding principles. Driven by design, these principles eliminate waste and pollution, circulate products and materials at their highest value, and regenerate nature. The built environment currently operates under a take-make-waste linear model that – for more than a century – has, and continues, to put significant pressure on the climate and biodiversity. Transitioning to a circular economy offers a comprehensive system-level approach to transform the way we source materials, build infrastructure, and use assets.
The UNFCCC report emphasises that better fundamental design of cities is already eliminating waste and bringing materials into a circular system. But there is more work to be done, as construction is one of the biggest contributors to the remaining 45 per cent of GHG emissions.
The construction and refurbishment of buildings alone accounts for 11 per cent of total GHG emissions in our cities. A majority of this results from the production of cement, steel, aluminium, and plastic. Despite this heavy carbon footprint, half of the aluminium produced each year does not make it to a final product, instead becoming scrap, and the construction industry is also identified as the UK’s second-biggest producer of plastic waste.
These issues with waste blight the construction process, with 15 per cent of building materials wasted during the construction process, and when a building is torn down most of its materials end up in landfill.
Companies which choose to revolutionise their practices, motivated by clear socio-economic and environmental imperatives, safeguard not only the environment around them, but also as businesses make themselves appealing investments for investment and asset owners. To truly galvanize change, the UNFCCC argues there needs to be a clear framework. By applying circular economy principles to construction, it could reduce emissions from the construction sector by 2.1 billion tonnes by 2050. But how can we put this into practice?
Making better use of existing buildings
While the expected structural and usable lifespan of a standard building is between 50 to 100 years, in reality value is often judged to be lost after less than 30 years — and this loss in terms of desirability and functionality often leads to demolition as the first solution. By applying circular economy principles, a building’s value can be maintained for much longer, preventing materials from ending up in landfill or incinerators, and simultaneously reducing the need for new materials.
Simply extending the life of existing buildings could reduce GHG emissions by 1.3 billion tonnes of CO2e per year by 2050. The transition to working from home for many during the Covid-19 pandemic meant more than one million square feet of office space in London alone was given up between March and September of 2020. In order to extend their lifespan, many of these properties are earmarked for conversion to residential properties, which also offers the potential to limit new housing needs on the city’s periphery, limiting resource use, associated emissions, and encroachment into green belt areas.
New building design
When there is a need for new buildings, they should be actively designed with sharing and reuse in mind, reducing the likelihood that they will become outdated or unusable. Beyond how the space is configured and used inside, design also dictates how a building is put together, what materials are needed, and whether waste is an inevitability in construction or not. By ensuring all materials used in the construction of buildings are entirely necessary and are used, GHG emissions can be reduced by 1.2 billion tonnes of CO2e per year.
Design strategies that can achieve these reductions include incorporating prefabricated building elements that reduces material demand and eliminates waste. This could reduce on-site waste generation by up to 90 per cent compared with traditional construction. Permanent modular structures such as this can also be complemented by temporary modular structures that allow for easy relocation rather than demolition, and together these strategies have been found to offer up to 60 per cent material cost savings.
Reusing and recycling
Poor design, coupled with a lack of information about a building’s material composition, contributes significantly to the fact that only 20-30 per cent of construction and demolition waste is currently reused or recycled. These unusable or unsuitable buildings should be viewed as material banks, as careful disassembly can facilitate material reuse and recycling, which combined prevents 0.6 billion tonnes of CO2 emissions every year.
In order to facilitate this process, building components need reliable and standardised information, such as a digital ‘passport’ that clearly defines the material composition alongside possible reuse options. As a notoriously fragmented industry, with sub-contractors designing and developing buildings often without interaction with one another, this standardisation would allow for less material wastage.
To the future
By designing built environments that are modular and diverse, not only can the sector optimise space but also leave room for nature to thrive within and beyond urban areas. We can limit associated negative impacts on biodiversity by keeping buildings and materials in use, reducing the need for new construction and material extraction. Where new materials are needed, switching to renewable materials produced regeneratively can help the sector actively rebuild biodiversity and safeguard the health of ecosystems.
Tansy Robertson-Fall is senior editor at the Ellen MacArthur Foundation.