The key role of contractors in driving carbon reduction
Key takeaways
Early contractor engagement is crucial for saving carbon throughout the project lifecycle
Innovative material selection and construction techniques can significantly reduce carbon footprint
Continuous monitoring and feedback are essential for effective carbon management
As the construction industry continues to grapple with its carbon footprint, the role of contractors in influencing sustainable outcomes has never been more crucial. Attention tends to be drawn toward design-stage interventions when it comes to saving carbon. However, the expertise that contractors bring to the table can also significantly impact a building's overall carbon performance.
Key to the success of contractor-led interventions is early engagement. With engagement throughout the project lifecycle, contractors can ensure sustainability is a focus from planning to handover, effectively managing carbon emitting resources. And, while design teams can introduce philosophies that will ensure developments function in carbon efficient ways, innovative contractors can lower carbon footprints by working with better materials, technologies, and buildability considerations.
In 2021, Mace pledged to remove 1,000,000 tonnes of carbon emissions from our clients’ operations by 2026. When this target was achieved in 2023, we increased it to 10 million tonnes. Drawing from our experience across several major projects, we've identified five key areas where contractors can make a meaningful difference in reducing embodied and operational carbon.
1. Early contractor engagement
Design teams and contractors have the potential to collaborate to improve sustainability outcomes.
A prime example of this is The Daubeny Project at The Oxford Science Park. Early collaboration enabled us to re-engineer the foundation solution, delivering significant savings in carbon, cost, and programme duration. By moving from a traditional piled foundation to a geostruct active raft design, we not only addressed variable ground conditions and mitigated flood risks but also reduced the use of concrete and steel reinforcement by thousands of tonnes.
This innovative approach resulted in a carbon dioxide equivalent (CO2e) reduction of approximately 3,000,000kg/C02e, while maintaining the project’s structural integrity and performance. Success was achieved by working collaboratively with the design team and Subterra, the build contractor, to validate and implement these changes before construction even began.
2. Material selection and innovation
The principle is simple: building less equals less carbon.
However, the execution requires careful consideration of materials and innovative construction techniques. This approach goes beyond simply selecting low-carbon materials – it's about rethinking how we build.
For example, at Panorama St Paul’s, the redevelopment of the former BT London HQ at 81 Newgate Street, over 75% of the existing structure is being retained, cutting the carbon footprint in half and achieving carbon savings of 465 kgCO2/square metre. By working closely with architects Kohn Pedersen Fox Associates (KPF), we replaced traditional concrete piles with a more environmentally friendly steel pile solution, saving 296 tonnes of carbon. Additionally, significant use of the original structure, including over 1,500 tonnes of Portland stone and granite from the façade, has further reduced the project’s embodied carbon.
3. Embrace innovation for better outcomes
Such optimisation is only possible when contractors influence material choices and methodologies early in the process.
Forward-thinking clients are embracing this approach and, with it, finding opportunities to leverage the latest technology for positive gains. Using innovation funds and collaborative partnerships can allow teams to invest in carbon-reducing technologies. For example, at Heathrow Airport, we are piloting AI-driven concrete batching systems that optimise cement content based on weather forecasts, reducing cement usage while maintaining performance. Combined with 'smart rock' temperature sensors that monitor concrete curing (heat of hydration), these innovations allow us to fine-tune material usage and reduce carbon without compromising program requirements – and in many cases improving it.
4. Elevating carbon to business-critical status
The traditional project triangle of cost, time, and quality is evolving into a diamond, with carbon taking its place as an equally critical factor. This shift requires a new approach to project evaluation and decision-making, where carbon implications are weighted alongside commercial considerations.
This has been the case with our current project at the European Centre for Medium-Range Weather Forecasts (ECMWF), being built for the Government Property Agency, which has been designed from the ground up as a net-zero carbon development. At a target embodied carbon figure of 500 kgCO2e/square metre at RIBA Stage 4, this will significantly undercut the current LETI baseline for non-domestic buildings, which stands at about 1,000 kgCO2e/square metre.
5. Continuous monitoring and feedback
Effective carbon management requires continuous monitoring and feedback throughout the project lifecycle. Contractors can implement robust tracking systems to measure carbon emissions at various stages of construction. This data can then be used to make informed decisions and adjustments, ensuring that the project remains on track to meet its carbon reduction goals.
At Mace, we use a carbon reporting tool that allows us to track and report carbon savings across our projects. This tool provides data on carbon emissions, enabling us to identify areas for improvement and implement corrective actions promptly. By maintaining a focus on continuous improvement, contractors can drive ongoing carbon savings and enhance the sustainability of their projects.
Looking Ahead
As the construction industry continues to evolve, the role of contractors in driving carbon efficiency is becoming increasingly important. Through early engagement in design stages, innovative use of materials, leveraging AI and smart technologies, integrating carbon costs, continuous monitoring, and close collaboration with clients and design teams, contractors can significantly influence carbon savings in construction projects.
By adopting these strategies, we can not only meet the growing demand for sustainable building developments but also contribute to a greener, more sustainable future for the construction industry.
