In a year that has seen the UK host COP26 and some of the world’s biggest businesses commit to ambitious net zero goals, engineers are taking a new approach to sustainable design that builds on the carbon footprint calculations already commonly used in most sectors.

Carbon impact is measured using three scopes. Scope 1 measures an organisation’s direct emissions, Scope 2 takes into account indirect emissions from purchased energy and Scope 3 looks at emissions in the company’s supply chain.

Engineers are now talking about “Scope 4”, an unofficial term that refers to the emissions that can be avoided by good design of products and services.

Positive environmental impact can be achieved by improving the sustainability of engineering design. So how are engineers doing things differently – and what impact could this have on the UK’s efforts to achieve net zero by 2050?

Engineers are looking hard at the carbon footprint of different materials so that they can make more sustainable choices when designing products and processes. Concrete, for example, is known to have a very high carbon footprint which is why the cement and concrete industry is exploring ways to improve its reputation. Production of cement, the key ingredient in concrete, accounts for around 7% of global CO2 emissions. The Global Cement and Concrete Association (GCCA) is leading an industry collaboration to meet net zero targets but engineers are working on today’s data and need to make choices based on what is happening now. In the construction sector, it isn’t just the type of material. Reducing the amount of construction material used in the design process lowers emissions and improves efficiency. This requires engineers to think carefully about alternative construction and design methods to reduce the amount of concrete needed.

Spare space on a manufacturing site can be used to develop custom engineering solutions to sustainability challenges. Polly Osborne, an engineer specialising in sustainability at Burns & McDonnell, said in an article for the Institute of Mechanical Engineers earlier this year that, when designing a new substation for the HS2 enabling works, Burns & McDonnell included an on-site rainwater harvesting system, avoiding the need for a water supply line to wat was a remote and rural location. “Saving resources in this way can make a project more sustainable, and more cost efficient too,” she explained.

Transport is another area where Polly thinks engineers and manufacturers can focus their decarbonisation efforts.

“We've all got an awful lot better at working remotely during the past year, and consequently have reduced emissions generated by transport. As we return to the "new normal" we need to continue to adapt to enhance and sustain the benefits of this trend on our projects,” she said.

More remote working and greater use of technology, particularly with the development of smart factories, will help engineers reduce carbon impact. Furthermore, Polly points out that procuring materials and services through local suppliers can additionally minimise transport distances. She says clients are asking their suppliers to do this and expecting it as standard.

“Not only is this type of mindset good for sustainability, it’s good for the local economy and community relationships,” she said.

Another key element of engineering design and sustainability is circular economy principles, to reduce the consumption of finite resources. Choosing components that can be reused or refurbished at the end of their life or the products life and making designs modular so that they can be repaired easily is a growing trend. This type of approach is relevant across all manufacturing and engineering sectors and is likely to become an important factor in the years ahead.