The materials we choose have an impact on our climate, writes Ian Taylor, partner at Feilden Clegg Bradley Studios
All those hidden materials. Retaining structures and foundations. The surfaces of our pavements and roads. The walls of our buildings, their colonnades and their roofs. The decisions we take about how long we need these structures to remain in good condition, how long they should survive before being renewed; replaced by different functions, higher densities, or transformed into new public spaces.
Our urban and rural fabric faces continually changing demands and economic forces. But while the construction industry has been thinking about reducing future energy use and building more efficiently to reduce waste, we have deferred considerations of the impacts of the actual manufacture and consumption of the things we use to build our environment.
So what are the impacts? We have to start from the raw materials we specify. In our Carbon Counts exhibition we feature samples of 10 materials commonly used in contemporary architecture. Each totem contains a sample that represents the volume of material that can be produced with a carbon impact of 1kgCO2e. The larger the sample size, the smaller the carbon impact.
Two of the materials in the exhibition are from regenerative sources: cross-laminated timber and bamboo, which have locked in that same 1kg volume of CO2 and therefore have negative impact values. It becomes clear that using materials of high and low impact in combination could lead towards carbon-neutral construction.
In addition to the production impacts of each material are the other processes that contribute to carbon impacts over the building’s life: transport, further manufacture, installation, wastage, repairs, maintenance, refurbishment, replacement, demolition, transport to landfill – perhaps reuse.
Getting to grips with embodied carbon is not straightforward. We undertook the Carbon Counts exhibition to start conversations; we hope that people passing our office will call in to take a few minutes to investigate; that visiting consultants and clients will want to find out more; that events held here will instigate information sharing and workshops; that we can develop collaborations towards solutions.
Time is of the essence. What we build in the next 10 years before 2030 could contribute as much CO2 as the following 60 years of those buildings in use. What we use to repair, maintain and how we demolish those buildings over the next 60 years could contribute the same again. This is in a world context where resources are inequitably distributed and where we urgently need to hit net zero-carbon targets.
Getting exact answers is difficult. There are many variables at play. But we have to start this change: what we use in construction now has an immediate effect. The carbon emissions created during construction have an impact 30 times larger than the annual carbon in use of the completed building.
This puts 2030 targets into perspective.
Carbon Counts is an exhibition presenting the carbon impacts of 10 of the most common materials used in architecture today. Open until 27 March, Monday-Friday, 09.30-17.00