Embodied Carbon vs Operational Carbon
Zenon Group (before Superstructures) explores the critical distinction between embodied and operational carbon, highlighting how both must be addressed to support the transition to a more sustainable built environment.
It has long been recognised that to limit the impacts of climate change and avoid reaching critical environmental thresholds, global warming must not exceed pre-industrial levels by more than 1.5 degrees. Despite international efforts and commitments made since 2015, temperatures continue to rise, with 2023 confirmed as the warmest year on record.
The built environment is a major contributor to this challenge, accounting for approximately 40% of the UK’s carbon emissions and around 60% of total waste. To effectively reduce this impact, attention must be focused on two key areas: embodied carbon and operational carbon.
What is embodied carbon?
Embodied carbon refers to the greenhouse gas emissions associated with a building’s entire lifecycle, including the manufacturing of materials, transportation to site, construction processes, maintenance, and eventual demolition or disposal.
What is operational carbon?
Operational carbon represents the emissions generated from energy consumption during the use of a building, such as heating, lighting, and powering appliances.
What is currently being actioned to help reduce the demand for fossil fuels?
The growth of renewable energy sources is already helping to reduce operational carbon. As energy systems become cleaner and more efficient, reliance on fossil fuels continues to decline.
However, as operational carbon reduces, embodied carbon is expected to become the dominant source of emissions within the built environment potentially exceeding 50% of total emissions by 2035.
Currently, there is limited legislation driving embodied carbon reduction, and decision-making within the industry is still heavily influenced by cost.
Our commitment, what is our responsibility as Structural Engineers?
At Zenon Group (before Superstructures), we recognise that while structural engineers have limited direct control over operational carbon, we can influence it through early collaboration with architects and building services engineers.
More importantly, we play a crucial role in reducing embodied carbon by shaping design decisions, advising on materials, and optimising structural systems.
How can we optimise design through lean design?
Lean design focuses on reducing unnecessary material use and improving efficiency.
One of the most effective approaches is reusing or adapting existing structures rather than building new ones. Even partial reuse such as retaining foundations can significantly reduce embodied carbon.
Other strategies include:
Designing elements to maximise efficiency and minimise waste
Reducing structural weight to decrease foundation requirements
Challenging conservative design assumptions where appropriate
What material changes can we make to become more sustainable?
Material choice plays a key role in embodied carbon reduction. Natural materials with minimal processing tend to have lower carbon impacts, while heavily manufactured materials often have higher impacts.
Structural engineers typically work with four main materials:
Masonry
Reinforced concrete
Steel
Timber
Each has its own considerations:
Masonry: Improved detailing and design can extend lifespan and reduce additional reinforcement needs
Concrete: Reducing cement content and optimising structural forms can significantly lower emissions
Steel: Efficiency in design and reuse of materials can greatly reduce carbon impact
Timber: A renewable, carbon-absorbing material when sourced and detailed correctly
Alternative materials such as cob, straw bales, or bamboo may also be considered where appropriate.
Collaboration and raising awareness through influencing the brief
Achieving meaningful carbon reduction requires early collaboration between designers, clients, and the wider project team.
Key decisions such as structural layout, span lengths, and material selection have a major impact on carbon outcomes. Even small changes, like introducing a column to reduce span or selecting alternative materials, can deliver significant savings.
Balancing embodied and operational carbon is essential. A holistic approach ensures that improvements in one area do not negatively affect the other.
