A doughnut-shaped solution to help save the world

As we draw closer to COP26, many built environment professionals will be reflecting on how they can operate in a more eco-friendly way. Overall, I think it comes down to three magic words that are all essential to true green construction: Reuse, repurpose and reimagine.

These values must be at the top of the list for anyone embarking on any construction project today, whether new-build or retrofit.

Building has long championed cleaner and greener industry practices, and has explored many big questions. A major conundrum is, “how can construction save the world?” And I would say, “by adopting the principles of  of ‘doughnut economics’ ”.

It is a term pioneered by a brilliant economist called Kate Raworth and, if you have not read her book, I suggest that you buy a copy. It should be essential reading for everyone in the industry, from specifiers through to contractors.

We need to be hitting the sweet spot of building for necessity, not gratuitously – as has often been the case in the past

Simply put, it presents a visual framework for sustainable development, which is represented by a doughnut shape, starting from the middle and moving progressively out. It essentially seeks to strike a balance between the environment and our societal priorities.

Using construction as an example, it means we need to be hitting the sweet spot of building for necessity, not gratuitously – as has often been the case in the past.

More construction with limited purpose or value pushes us further towards the cusp of Raworth’s doughnut. It is a hard stop boundary and, if we go beyond it, we will be irreversibly damaging our planet and society simultaneously.

So, the sector needs to adopt a more measured and responsible approach to future projects. The question that should always be asked is, “is it necessary?” I think you would find that, often, a lot of what we currently build is not.

However, it is not all doom and gloom. Construction also has the ability to get its own house in order, or in the words of Building’s question to “clean up its act”. It is a universal challenge, but use of materials is at the heart of the issue and provides both the catalyst for the problem and the solution.

There is no difference between building a casino in New York and a hospital in Lagos in terms of material waste. Whether you think that one should be prioritised over another is a different question

For example, there is no difference between building a casino in New York and a hospital in Lagos in terms of material waste. Whether you think that one should be prioritised over another is a different question, but it is possible to clean up our act in terms of how both are designed and built.

Ultimately it means using less stuff – it is as basic as that. We waste material hand over foot in structural design, and that is an evidence-based assertion.

The first thing that we need to do is stop wasting materials. By just sticking to codes of practice, we will reduce consumption by anything up to half. It is terrifying how much gets wasted.

Then, of course, there are conversations questioning whether we need the buildings in the first place. Look at the overall design – for example, questioning the size of the floor loading, which has a huge influence on the amount of materials used in a building.

Are we still aiming to design buildings in which hundreds of people are to be packed like sardines on one floor? Current design trends suggest not, so we can start designing more lightweight structures, accommodating more realistic numbers of people with less material.

That is only scratching the surface and I think there remains a massive awareness programme to be undertaken across the sector. Things are gradually getting better, but not at quite the pace that I – and some others in the profession – would like to see.

The Institution of Structural Engineers treats structural safety and sustainability as equal partners, and this is reflected in the Structural Awards, in which the sustainability credentials of any project encompass waste minimisation and long-term societal benefit.

What is great about this year’s entries is that the practices involved have responded to our changing criteria, and it is pleasing to see that this year’s shortlisted projects are definitely moving towards the “sweet spot” of Raworth’s doughnut.

I hope we can maintain this positive – if gradual – momentum as we get closer towards net zero 2050. Only time will tell and continuing on this dessert-led theme, the proof will, ultimately, be in the pudding.

Professor Tim Ibell was president of the Institution of Structural Engineers in 2015 and is fellow of the Royal Academy of Engineering. He is professor of the faculty of engineering and design at the University of Bath and chair of the judges for the Structural Awards 2021