Jay Morton of Bell Phillips Architects calls for political and regulatory action to accelerate the adoption and development of low-carbon and zero-carbon construction methods.

On its completion in 2017 Dalston Works by Waugh Thistleton was the world’s tallest CLT building at 33 metres high. Post Grenfell fire regulations have banned the use of combustible materials, including structural timber, in buildings above 11 metres. PHOTOGRAPHS BY DANIEL SHEARING

In her speech at COP 26 the prime minister of Barbados Mia Mottley warned that climate commitments “are based on technologies yet to be developed. These are at best, reckless and at worst, dangerous.” This cannot be truer than with the construction sector, which is currently responsible for 38 per cent of global carbon emissions. For too long, the focus has been on the energy use of finished buildings and not enough on the construction process.

Around the world this minute, foundations are being dug, concrete is being poured, steel is being forged and bricks are being laid – all emitting vast quantities of carbon from the extraction of raw materials, manufacture of products, transportation and the construction process itself. But if it has air source heat pumps, photovoltaics and flowers on the roof then it can be considered ‘sustainable’. Given the sector is set to grow 42 per cent by 2030, this needs to change. Innovation and technology are key to delivering the low-carbon and zero construction methods we need.

Pre Grenfell, cross-laminated timber (CLT) provided a solution to reduce carbon in both low-rise and tall buildings. As trees grow, they absorb carbon dioxide. Known as sequestered carbon, this CO2 stays stored within the timber even as it is processed into a building material. Dalston Works by Waugh Thistleton provides 121 homes, and was on completion in 2017, the world’s tallest CLT building at 33 metres high. The environmental gains of using CLT were immense. Not only does the timber sequester carbon, but the building weighs one-fifth of a concrete structure, hence reducing the quantum of concrete required in its foundations. On top of that, the number of deliveries to site was reduced by 80 per cent. Now, there are even taller examples across the world and many more in planning stages, including the 29 storey (98 metre) Woho tower planned for Berlin’s Kreuzberg district.

Dalston Works under construction. Not only does the CLT sequester carbon, but the building weighs one-fifth of a concrete structure, reducing the quantity of concrete required in the foundations. Photography by Daniel Shearing

In the UK it has taken over 20 years for CLT to become mainstream and even then, it is frequently priced out by more traditional methods. This is an example of how long it takes to adopt new methods of construction within the industry. It is also unlikely we will see a Woho in the UK anytime soon as the post Grenfell fire regulations have banned the use of combustible materials, including structural timber, in the external facade of all residential buildings above 11 meters.

This leaves us in a predicament, and we must now look to technology for an answer. Beyond what we have today, other solutions in the pipeline include carbon capture within concrete using new buildings as a carbon store. Others include reusing and recycling existing materials, plus material passporting so elements of buildings can be reused directly. Yet we are a way off any of these solutions becoming mainstream.

It is pointless to discuss these potential advances while the regulatory and economic framework remains prohibitive. The industry could be using hybrid structures, such as CLT alongside steel or concrete, but the fact that these details are not standard practice means it can be difficult to get approval from building control and warranty providers – especially in residential contexts.

When new approaches are trialled, it’s standard practice to price in an additional contingency budget to account for the ‘complexity’, further inflating potential costs. In terms of reusing existing buildings for new uses, costs can sometimes impact viability. Currently, VAT is paid on retrofit but not on new build. This should be reversed. In addition, products that can prove to be low- or zero-carbon, from manufacturers that seek to do the right thing, should be VAT exempt.

Construction is a risky business, and architects, engineers and contractors all want to fulfil their obligations to their staff, as well as make sure that buildings are high quality, legally compliant and safe. The construction sector is notoriously slow to evolve and the 2.6 per cent average profit margin across the sector results in an industry that is hyper-focussed on keeping risk and, by extension, costs to a minimum. Without improved benchmarks and regulation, progress is slow and sporadic.

The UK began to move in the right direction in 2006 when Gordon Brown announced a plan for all new homes to be net-zero by 2016. But the plan was scrapped by the Cameron regime in 2015. Imagine where we would be now; we could have been world leaders in net-zero construction. Definitive regulation, such as the net-zero target, would have created a level playing field across the sector whilst driving innovation.

In light of the climate crisis, we need to ensure that we are always using the best solutions available to address design challenges. The best minds need to come together with serious investment and government support to back it up. It will require us to push ourselves, our peers and partners, but in the words of Mia Mottley, if we are serious, we need to “Try harder, try harder, try harder.”