Concrete: brutally beautiful but in need of a climate reboot

#Concrete has proved to be a very versatile material for constructing buildings that can last for several decades. But its environmental impact has led to pressure to find more eco-friendly versions for truly #sustainable #cities.

For many of us concrete buildings are things of beauty. Thanks to its versatility and adaptability, concrete can be used to create a limitless number of shapes and acute angles. One of the most famous forms is brutalism known to Londoners via the Barbican Centre and the Trellick Tower among hundreds of other examples.

An exhibition of the winners of a photographic competition, Concrete in Life, based on a shortlist of some 21,000 images from around the world taken in 2023 ends this week (13 April) after being extended due to popular demand. Luckily the winning and shortlisted images will be available on the sponsor’s website.

The winning image in the Urban Concrete category is of the Armstrong Rubber Building in New Haven, Connecticut, which photographer Owen Davies describes as having “striking geometry and sheer mass” with a  “wonderfully sculpted concrete façade”. The overall winner was a captivating image of children playing with kites on a large, stepped concrete ramp at Mexico’s Teopanzolco Cultural Center.

It is no secret, however, that the production of concrete has a major environmental impact. Each year, more than 4 billion tonnes of cement are produced, accounting for around 8 per cent of global CO2 emissions. According to research, to bring the cement sector in line with the Paris Agreement on climate change, its annual emissions will need to fall by at least 16 per cent by 2030.

Filling in solutions

The industry is understood to be keen to make their product more eco efficient and ideas abound. One is the use of green concrete that contains fewer natural resources and more inputs known as supplementary cementitious materials such as fly ash, slag cement, and silica fume.

Another important innovation is permeable concrete, which can mitigate the impact that traditional concrete has during heavy rainfalls of allowing the water to run off into drains, compounding the impact of rising river levels that can cause floods. Concrete can also contribute to climate change by adding to the “urban heat island” effect that sees temperatures peak higher in built-up areas. This can be countered by so-called cool concrete that includes materials that shine solar energy back into the atmosphere.

One study identified a host of innovative designs and practices. These include self-healing concrete that can autonomously carry out repairs, 3D-printed concrete that can save energy and waste by applying the exact quantity needed to any surface, photocatalytic concrete that contains compounds that can break down pollutants in the air, and insulated concrete forms that include a foam to provide temperature insulation.

There are also practices and construction methods that can reduce the environmental impact. One that is common to all polluting activity is carbon capture, usage and storage (CCUS) whereby the emissions generated are captured and then either used or stored, usually underground to prevent its release into the atmosphere. Another is electrification of building vehicles and operations, reducing the need for fossil fuels: this YouTube video in Oslo (at 2’15”) shows how it can be done.

But the land development industry, architects and planners can also make a contribution by looking to find ways to retrofit and upgrade buildings rather than demolishing existing structures, which releases carbon locked into the building itself. The Greater London Authority’s London Plan supports that, and the City of London has adopted a “retrofit first policy. The latter cites the example of the proposed One Exchange Square redevelopment that it says will retain 90% of the existing structure including foundations, leading to a 62.2% reduction in carbon emissions.

The demand for buildings and infrastructure is set to continue, matched by a growing desire that they be delivered in as least an environmentally damaging way as possible. The hope will be that innovative advances in both building materials and construction techniques combine with tougher industry standards and tighter planning policies to reduce the climate impact and lock in sustainability.

If so, entrants into future Concrete in Life awards will show safe, durable and resilient structures that underpin the goals of minimising waste and energy and embracing concepts of renewability and circularity.