21st century challenges call for modern methods of construction

The global construction industry has an enormous amount of work to do over the coming decades: decarbonising the built environment, delivering the infrastructure of a net zero world, building climate-resilient homes for a growing population and healthcare facilities for an ageing one. We need renewable energy, data centres, lithium battery factories, high-speed rail – the list goes on. 

To do all of this, it is essential that we resolve the industry’s longstanding issues with productivity, efficiency and recruitment. Rising construction costs are partly due to higher material prices and tight labour markets, but they also highlight the sector’s inefficiency and failure to modernise. According to investment bank ING, prices in the EU construction sector almost doubled between 1995 and 2020, while those in manufacturing increased by less than 20%. In contrast, labour productivity has almost doubled in manufacturing over the last 25 years, but increased by only 20% in construction.

This is where modern methods of construction (MMC) hold the key to both radically improving the productivity of the construction industry, and driving out embodied carbon and waste. Traditionally, construction has involved transporting many thousands of individual components to site to be assembled. Much of this work could be carried out in a factory environment instead, improving quality, safety, collaboration and productivity while reducing waste. MMC encompasses a wide range of new materials, methodologies and technologies. This ranges from fully furnished modules that can simply be connected together on site, to elements that are assembled as a kit of parts, to on-site 3D printing or a digital twin that contains detailed information about every single component of a built asset. Many of these ideas have been around for a while – even decades – but with advances in digital technology we are now able to realise their full potential.

At WSP, we have been working with developers, contractors, manufacturers and governments to engineer innovative solutions and implement them around the world – sometimes unlocking projects that could not previously be delivered. In London, using a lightweight steel-timber hybrid solution meant we could add four storeys on top of an existing building without any additional strengthening to the existing structure or its foundations. Mass timber is a technology with huge potential: a comparison study for a typical office floor plate found that a steel-timber hybrid floor plate had nearly 50% less upfront embodied carbon when compared to traditional frames in steel-composite deck and reinforced concrete. The reinforced concrete frame was also 80% heavier, increasing the size and type of foundations and required five times as many deliveries to site.

Another study found that changing from a traditional concrete slab to a panellised system made in a factory reduced the number of deliveries to site from approximately 100 to 50 – and using a volumetric modular system cut to just 12. We also found that using either volumetric construction or a kit of parts approach can save up to a year on the programme for a 45-storey tower.

We are seeing the benefits of MMC on the ground too. For example, at The Grange University Hospital in Wales, using off-site construction for 50-55% of the project cut 42 weeks from the programme, and increased productivity by 45%. InnoCell, a 17-storey accommodation block at Hong Kong Science and Technology Park, was completed six months early using a system of steel modules – which could be simply unbolted and replaced in future. And on City Rail Link in Auckland, New Zealand using digital tools for data processing, documentation and modelling tunnel services saved thousands of hours in design time. 

We see the greatest opportunities where a manufacturing-led approach is implemented right from the start of the process. MMC is fundamentally about economies of scale, and this applies to design as well as construction. We need to rethink not only how buildings and infrastructure are constructed, but also how they are designed. Rather than starting from first principles every time, a manufacturing-led approach would allow us to select from an optimised, compliant catalogue of components, customising them to suit the context, user experience and desired aesthetic. This is not about producing cookie-cutter buildings, it is about stripping out duplication and being honest about where choice adds value, and where it just contributes to waste. 

Standardising floor-to-floor heights, structural grids or cladding panel brackets will not lead to a homogenous built environment, but it would make both construction and later refurbishments simpler and quicker. Designing a staircase involves 150 different decisions, and we make them intuitively each time. But we do not need every staircase to have a unique structure, or to design every bathroom from scratch. The layouts could be standardised but configured with different fittings and finishes – with real-time cost and carbon calculations. On one housing programme we are working on in the Middle East, even the most basic level of configuration offers thousands of variations. 

There will always be a balance to be struck between the digital and the artisanal, and this will vary by sector. Greater standardisation will be most valuable on high-volume repeatable projects where cost and speed of delivery are key, whereas for a concert hall or a statement public building, a more bespoke approach is likely to be more appropriate.