From giant Lego-style bricks to artificial reefs, how the construction industry is using tech to tackle climate change

The problem of stolen manhole covers in Turkey might seem an unlikely starting point for a new way for buildings to withstand earthquakes and tackle the construction industry’s environmental issues, but when a Turkish businessman heard about a new material that prevented the thefts, it sparked an idea.

Cast iron is traditionally used to make the manhole covers that protect drainage systems. But back in 2010, a spate of thefts of the covers for scrap metal in Turkey meant that an alternative, with equally strong material needed to be used to secure them. And when Engin Yesil read about this super-strong composite in news reports, he wondered whether it could be used to construct buildings that were able to withstand earthquakes — a significant risk in Turkey.

Yesil began manufacturing the composite, known as Renco (short for “renewable composite”) consisting of up to 40% repurposed materials including resin and fiberglass. Since 2011 more than 200 buildings in Turkey have been built using Renco blocks, which fit together like Lego bricks and are secured with glue.

Yesil wondered whether Renco had potential in the U.S., and after more than a decade of research and testing, Renco was used to build an apartment complex in Palm Springs in 2023.

Along with being able to withstand catastrophic Category 5 hurricanes (the highest rating on the Saffir-Simpson Hurricane Scale and an increasing phenomenon due to climate change), Renco claims to be greener than other building materials. The construction sector is “by far” the largest emitter of greenhouse gases of any sector, according to a 2023 U.N. report, making up 37% of global emissions.

Renco weighs about 80% less than concrete, meaning more of it can be transported per truck, and also has 82% less embodied carbon than structural steel, according to a report by the Athena Sustainable Materials Institute commissioned by Renco. Embodied carbon refers to the emissions released during the manufacturing, transportation and disposal of building materials.

Renco is also 100% recyclable, according to Patrick Murphy, managing director of Renco USA. He said the new composite marks a step-change in building materials. “In construction, there’s basically three ways to build, right? You have concrete, steel and wood, and that’s basically been the same thing for 100 years … so this is really the fourth way to build that’s been approved,” he told CNBC by video call.

This year, Renco will begin manufacturing in the U.S. for the first time, with a Florida factory opening in the coming weeks that can produce enough building blocks for around 9,000 average-sized apartments.

As with other materials used in construction, Renco isn’t without an environmental impact, with blocks currently shipped from Turkey to the U.S. while the Florida factory is being completed. And, while Renco’s Turkish manufacturing plant is powered by renewable energy, about 12% of the electricity generated in Florida comes from nuclear power plants.

Renco isn’t the only company aiming to build more sustainably. On the other side of the Atlantic, a British firm is designing buildings using a well-known material — wood. Architecture firm Waugh Thistleton designed its first building made from cross-laminated timber, or CLT, in 2001 and has since built around 30 in the U.K., Europe and the U.S. It uses products certified by the Forestry Stewardship Council, or equivalent, meaning the wood has to come from forests that are managed in ways that meet a number of internationally-agreed standards.

Building in timber rather than steel or concrete could achieve a 19% reduction in emissions, according to a 2024 study by the University of Arkansas, while a 2023 U.N. report urged the construction industry to shift to bio-based building materials such as sustainably sourced timber and bricks to decarbonize the built environment.

“The idea that we can build from replenishable materials has become something that has become increasingly important to us,” said Andrew Waugh, Waugh Thistleton founder and director. “And then the more you do it, the more you realize that there are health and wellbeing benefits to that, that actually people are much happier and healthier surrounded by natural materials than they are surrounded by polystyrene ceiling tiles and … drywall [wall panels],” Waugh told CNBC by video call.

But the U.K. has been slow to adopt wood as a building material, something that is “frustrating” to Waugh. Around 60% of the waste produced in the U.K. comes from the construction industry, according to a 2022 government report, whereas Waugh notes that building with wood produces little on-site waste. Again, building with wood is not without its environmental concerns: the timber used in Waugh Thistleton’s projects is often transported from Europe.

Another phenomenon caused by climate change is the rising level of oceans — compounded by land sinking at the same time.

In the coastal independent state of Monaco, known as a playground for the rich due to its low taxes, a newly-built “eco neighborhood” known as Mareterra has put sustainability at its heart. “With climate change, building on water will become a strategic approach for certain coastal areas,” according to Guy-Thomas Levy Soussan, managing director of the Mareterra development, in an email to CNBC. The development aims to be a “model” for how coastal cities can grow responsibly, Levy Soussan added.

During construction, a technique known as the “caisson” method was used, where 27 meter high reinforced concrete structures were built in the French city of Marseilles and floated to Monaco so as not to disrupt marine life. Alongside acting as flood barriers, they are habitats for marine organisms, Levy Soussan said.

So-called “eco-reef villages,” were also constructed. Made up of more than 300 modules, they were installed in the marine area the development sits on. Ecological “corridors” mean that fish can reach the villages, while a protected species of seagrass known as posidonia was relocated to provide an ecosystem. These eco-measures will be monitored for at least a decade and Monaco’s government will use insights to guide future maritime projects, Levy Soussan said.

Both Waugh and Murphy expect the construction industry to move towards more sustainable materials.

“It’s inevitable because, you know, the better that other industries become at reducing their carbon burden, then the more exposed construction will become as an outlier,” Waugh said.

Regulation may be the force the construction industry needs to become more sustainable, Waugh Thistleton’s founder added.

The UK Green Building Council has called for the British government to go further in its environmental aims for new homes, while in Singapore, for example, the government added proposals to its Mandatory Energy Improvement regime to include older buildings. It had previously focused on new buildings or those being extensively refurbished.

Murphy said the industry will “have to” reduce its emissions. “The industry has flown under the radar in many senses, right? People talk about airplanes and cars and cows, you know, a lot of other … emissions. A lot of people don’t realize how bad cement is and how bad that the built environment is.”

Embodied carbon has been a focus for the U.S. Environmental Protection Agency and construction company Skanska USA developed a tool, known as EC3, to help construction projects quantify their emissions.

Steve Clem, senior vice-president of project planning and sustainability at Skanska USA Building, said that the tool has encouraged some suppliers to reduce their embodied carbon.

When Skanska was evaluating concrete companies for a large project in Seattle, it showed each firm how their materials fared against each other in terms of embodied carbon, using EC3. “When different suppliers saw how their mixes stacked up against each other, they voluntarily took steps to improve their mixes at no cost to the consumer,” Clem told CNBC by email.

The vice president is positive about the future. “The construction industry is doing more for sustainability now than any other time in history, or at least since the industrial revolution … My hope for the future is that sustainable construction is the norm and many more people have the opportunity to live, work and play in carbon-free buildings,” Clem said.