From bridges to buildings, and roads to runways, the built environment is what shapes the world around us. But it also carries a heavy burden for the planet, with buildings and construction accounting for around 37% of global emissions, and around a quarter of the UK’s total carbon footprint.
Most efforts to decarbonise the sector focus on operational efficiency: insulating buildings, upgrading heating systems, or switching to renewable energy. But there’s another, less visible part of the problem: the carbon cost of the materials we build with.
Building materials like concrete, bricks, and asphalt are essential, but they’re carbon-intensive to produce. That’s where low-carbon construction comes in — introducing more sustainable versions of these essential materials, designed to lock away CO₂ instead of releasing it to lower the carbon footprint of construction projects
We’ve deconstructed how direct air capture can help building materials innovators to create climate-positive products that open up exciting new avenues for growth.
How low-carbon construction with direct air capture works
Right now, most building materials come with a high embodied carbon cost. But what if we could flip that around, so that making these materials actually removed carbon from the atmosphere?
In recent years, a growing wave of innovation has swept through the construction sector, with companies like O.C.O Technology pioneering new ways to embed CO₂ directly into the materials we build with. From carbonated aggregates to CO₂-injected concrete, these technologies are already being used to cut the carbon footprint of construction. But most of these systems still rely on CO₂ from fossil or biogenic sources.
Direct air capture technology connects building materials producers with the carbon in our atmosphere, providing a high-quality stream of fossil-free CO₂ that can be directly integrated into their products. By carbonating raw materials with atmospheric CO₂, producers can realise low-carbon or even carbon-negative building materials which also enable durable carbon removals.
Integrating direct air capture can allow producers to decarbonise construction materials without redesigning their products or production processes. Here's how it works:
1. Recovering CO₂ from the atmosphere
First, a direct air capture system selectively strips CO₂ from the ambient air, resulting in a concentrated stream of pure carbon. This CO₂ is sourced on-site exactly where it’s needed, eliminating the need for long-distance transport and associated new fossil carbon emissions.
2. Direct integration with production facilities
The CO₂ can then be directly fed into building material production facilities via a direct CO₂ pipeline integration. If DAC is being used as an ancillary CO₂ source or as part of an intermittent production process, a buffer tank can hold the atmospheric CO₂ at the correct pressure until it is needed.
3. Carbonating raw materials
Here’s where the all-important carbonation happens. Raw materials used to create building materials are injected with CO₂ to form stable carbonated minerals, which chemically fix the CO₂ in the material for thousands of years.
4. Curing, testing, and industrial use
As the material cures, it passively absorbs more CO₂ from the atmosphere. Once tested, the materials can be used as direct swaps to decarbonise construction projects. If the materials demonstrate that they have removed more CO₂ than their production emitted, they qualify for a carbon removal credit.
The world’s first DAC-to-aggregates demonstration
We’ve demonstrated this firsthand through our work with O.C.O Technology in a world-first project funded by the UK government. By plugging CO₂ from our direct air capture system directly into their aggregate production lines, O.C.O are able to produce a versatile carbon-negative manufactured limestone.
The aggregates they produce can be used just like traditional gravel or crushed rock to decarbonise essential building products like bricks, tiles, and slabs. They can also be used to produce low-carbon or even carbon-negative concrete. Given that concrete is the world’s most used building material, and aggregates are its core ingredient, the sustainable construction potential here is huge.
What makes this approach so compelling is its ease of integration. Direct air capture technology can be co-located and installed directly on a manufacturing production site, no matter how remote the location. The technology can integrate with existing processes and scale with demand, all without requiring any facilities redesign — proving that embracing clean technology doesn’t have to come at the expense of established production.
O.C.O supplies sustainable aggregates into a number of construction sectors, through its Manufactured Limestone or M-LS, which stores CO₂ in a stable form for thousands of years. Every 1,000 tonnes of M-LS produced captures the same amount as planting 4,000 trees every year.
Adding value with low-carbon construction
Low-carbon construction doesn’t just reduce emissions — it creates new value for construction businesses. Harnessing DAC technology and using atmospheric carbon in aggregates unlocks:
- Higher quality construction products: Research shows that the carbonation process can make cement-based materials stronger and more durable;
- Drop-in replacements: Low-carbon construction calls for simple switches, with carbon-neutral or negative aggregate fitting easily into existing concrete mixes and workflows.
- Supply chain resilience: Direct air capture provides a stable, on-demand supply of sustainable CO2 protecting production from CO2 shortages and price spikes;
- Simple logistics: Sourcing carbon from the atmosphere means there’s no need to import or transport the CO2 needed to create concrete;
- Additional revenue streams: Products which durably remove CO₂ from the atmosphere create the opportunity to generate high-quality carbon removal credits;
- New markets: With a guaranteed DAC CO₂ supply in any location, producers can take advantage of opportunities in regions where CO₂ supply is scarce or non-existent.
Low-carbon construction’s storage potential
The potential of carbon-storing materials is enormous. If just 10% of global concrete aggregate production was carbonated, it could lock away 1 gigatonne of CO₂ every year — or just shy of the total amount of CO2 emitted by global cement manufacturing in 2023.
Across all building materials, the built environment could store as much as 16 gigatonnes annually – that’s 50% of global emissions – making carbonated construction one of the biggest untapped carbon sinks on the planet.
Creating building materials that lock away atmospheric CO₂ also opens the door to added value, with the option to sell carbon credits, or expand their product portfolios to offer customers carbon-neutral or carbon-negative products which can command a higher price point.
Though there isn’t as much of a premium for selling carbon-negative products at present, (due to a need for greater regulation and incentivisation) this is set to change, with recent policy shifts in the UK putting pressure on construction firms to lower their carbon impact. Early pace setters within the building materials sector realise that investing in low-carbon innovation now can give them a leading market position and allow them to tailor critical technologies like DAC to their exact needs as sustainable construction policy catches up.
Direct air capture for low-carbon construction: proven, practical, ready to scale
Direct air capture offers building materials innovators both a standalone sustainable CO₂ supply solution — ideal for sites where transportation is more challenging — and a complementary CO₂ source which can be used to bolster the reliability of existing supply.
Integrating a direct air capture system to enable low-carbon construction introduces a traceable and measurable source of CO₂, with a small land footprint (vs. the large infrastructure needed for fossil-based or some biogenic CO₂ sources), that isn’t subject to the unreliable nature of the current commodity CO₂ market.
If you’re ready to build with air, we’re ready to help.
We’re working with innovators across the construction and building materials industry to deploy DAC on-site and unlock the value of carbon-storing building materials.
Contact our Sales team to learn more.
