Materials Matter

27 March 2020

Carbon Counts Exhibition


In the context of a climate emergency, architects need to address embodied carbon to have the greatest impact. Peter Clegg explores how we can do this, by understanding the characteristics of materials and using them appropriately.

The IPCC 2018 report told us we have less than a decade to repair the damage caused by CO2 emissions and the IPBES 2019 report substantiated biodiversity loss that placed us in extinction mode. But, it took a 16-year-old Swedish schoolgirl appealing to the UN and a 92-year-old television naturalist lamenting our impact on the natural world to begin to create a shift in attitudes.

Construction has a direct responsibility for nearly 40% of CO2 emissions worldwide, and the architectural profession is at the ethical epicentre of this. As someone who has been working for 40 years in low energy design, I cannot recall any time when there has been more enthusiastic support for making fundamental change, spearheaded of course by the younger generation.

When Steve Tompkins (of Howarth Tompkins) brought together a dozen or so of us from Stirling prize-winning architectural practices to talk about what we might do, the starting point seemed to be to devise a declaration about our impact on the environment and get as many practices as possible to sign up. At the time of writing the number in the UK stands at 845, but globally from more than 18 countries we now have over 3500 signatories within 8 months. Under the Construction Declares umbrella organisation we have environmental, structural and civil engineers and landscape designers.

The RIBA quickly responded with its 2030 climate challenge with a reducing set of targets for both operational (energy in use) and embodied (energy in construction) carbon. In November last year we saw 30 of London’s major developers and property owners, with £300 billion in assets under management, making their own declaration of how they intend to meet the Government’s declaration of a climate emergency.

FCBStudios’ declaration recognises the challenges we face in meeting the needs of society equitably and without breaching the ecological boundaries of the planet we inhabit. More specifically the declaration demands we raise awareness of the crisis and strengthen the ambitions of our clients and collaborators. It exhorts us to make better use of existing buildings and look to upgrade their energy performance. It urges us to monitor and publish data on energy use over time. It demands we look at whole life carbon costs from construction through to end of use and recycling, and apply regenerative design principles to everything we do.

The changes in practice are manifesting themselves in different ways. As a practice we have been focused on low energy design for 40 years, but our work has tended to be centred on operational energy and the reduction of electricity consumption. What has made such a significant change recently is the decarbonisation of the grid reducing the carbon costs of operating a building over a lifetime of, say 60 years, to way below the cost of constructing it. Our attention has refocused on the embodied carbon - the carbon costs of constructing a building and in particular those high carbon cost materials which require considerable processing to manufacture. Up to two-thirds of the lifetime carbon emissions for a building stem from this embodied carbon, half of which are emitted before the doors are even open. In the context of a climate emergency, we need to take immediate action and address embodied carbon to have the greatest impact.

Tackling embodied carbon isn’t about avoiding certain materials, it’s about understanding their characteristics and using them appropriately. Concrete in itself may not be the high emitter it is portrayed as, if it is used very efficiently. It starts by having an informed discussion about what we’re using and how. Can we rationalise the structure? Is there a more durable cladding material? How often will the windows be replaced?

We can also think about ‘growing’ our buildings: using materials such as timber and bamboo to absorb and sequester carbon as they grow and contribute in effect to a carbon positive building from day one. The exhibition ‘Carbon Counts’ that is currently in our London studio begins to pose these questions.

We set the unit of measurement at one kilogram of CO2 and looked at what volume of each of ten common building materials could be produced, releasing that one kilogram of CO2, or in the case of timber and bamboo, sequestering that one kilogram.

Embodied carbon is the new currency of building that we need to fully comprehend if we are to stand any chance of putting out the fire.

Peter Clegg

This article was written as the Listen piece for the April 2020 edition of Blueprint Magazine: The Materials Issue. You can buy the magazine online to read the full content of the edition.

The Carbon Counts exhibition presents FCBStudios research on the carbon impacts of ten of the most common materials used in architecture today.