
Building materials like bricks, concrete, and asphalt hold massive potential to store carbon. The production of building
materials alone contributes up to 11 billion tonnes of carbon dioxide equivalent annually. PHOTO/FILE
Imagine your home as a climate ally—every brick, roof tile, or concrete slab actively capturing and storing carbon dioxide (CO₂). For Uganda, where buildings seem to sprout overnight, this could be a game-changer.
A 2025 expert analysis estimates that using CO₂-storing building materials could sequester 16.6 ± 2.8 billion tonnes of CO₂ annually—nearly half the world’s emissions from 2021. But even beyond emissions reductions, they could also eliminate the environmental risks tied to alternative methods like deep-earth or oceanic carbon storage.
Science has established that stabilising the earth’s climate requires more than cutting emissions.
Net-zero means balancing residual emissions with their removal, particularly in sectors like heavy industry and aviation that require direct carbon dioxide removal (CDR). Traditional methods like carbon capture and storage (CCS) are effective but costly and risky.
Can all of the aforesaid be skipped en route to transforming our cities into carbon banks?
Building materials like bricks, concrete, and asphalt hold massive potential to store carbon. From 1900 to 2015, the cumulative mass of infrastructure materials produced was comparable to the weight of all human food, animal feed, and energy resources combined, a 2018 research from the ScienceDirect journal shows.
Unlike single-use items, these materials endure for decades, making them an ideal vessel for long-term carbon storage.
That is where physicists come in, suggesting that engineering these materials to absorb and lock away CO₂ could be revolutionary. Not only does it bypass the need for costly storage systems, but it leverages an industry already consuming billions of tonnes annually.
So, why dig deep or risk ocean ecosystems when we can redesign our built environment to become part of the solution?
Construction is one of the planet's worst climate offenders. The production of building materials alone contributes up to 11 billion tonnes of CO₂ equivalent annually, accounting for 10-23 percent of global emissions, the United Nations Environment Programme (UNEP) data shows. It further reveals that even when we strip out energy-related emissions, the industry still released 1.8 billion tonnes of CO₂ in 2016, amounting to five percent of global emissions.
Can the very materials responsible for this mess help clean it up?
Emerging technologies are rethinking materials like concrete, brick, wood, asphalt, and plastic, making them carbon positive. Imagine concrete that absorbs CO₂, bricks made with carbon-rich minerals, or timber buildings acting as long-term carbon sinks.
“Take wood. Timber buildings could become carbon vaults, trapping atmospheric CO₂ captured through photosynthesis. Concrete, the most widely used building material, can absorb carbon at the end of its life through a process called carbonation, undoing part of its emissions debt. Even alternatives like "green cements" and CO₂-enriched plastics are being tested, offering the chance to reverse emissions from their production,” data in a new research paper titled “Building Materials Could Store More Than 16 Billion Tonnes of CO2 Annually” and released on January 6, 2025, shows.
Pioneered by building and environmental researchers Elisabeth Van Roijen, Sabbie A Miller, and Steven J Davis reveals that the potential lies not just in carbon storage per kilogramme but in the sheer scale at which these materials are used. The trio of experts explored the carbon storage potential of common materials using 2016 consumption levels and found that replacing traditional inputs with biogenic materials or carbon-rich minerals could turn buildings into massive carbon sinks.
Bio-based plastics pack the most carbon per kilogramme, but are produced in smaller quantities, limiting their global impact. Concrete aggregates, while less efficient per kilogramme, have a huge storage capacity due to their widespread use.
What numbers are we looking at here?
Concrete and aggregates lead the way, accounting for 11.5 ± 1 Gt of the total. Their dominance lies in global demand, not carbon-absorbing power. But innovations in cement, such as magnesium oxide-based binders with biochar, are seen as ones that could capture up to 0.9 kg of CO₂ per kilogramme, unlocking another 2.6 ± 1.1 Gt.
“Bricks, with added biomass fibres or calcium hydroxide, could store 0.8 to 1.2 Gt of CO₂. Wood, with responsible forestry practices, could sequester 0.45 ± 0.09 Gt from a modest 20 percent increase in global consumption. The key is managing emissions from harvesting, transport, and decay,” the researchers note.
Even materials with low carbon-storing efficiency such as bio-based plastics and asphalt binders, can contribute if scaled appropriately. Although they represent less than five percent of the total potential, their integration adds valuable pieces to the larger puzzle.
Sensitivity tests confirm that increasing the use of low-carbon materials is essential to unlocking their full potential.
In the end, scaling material use amplifies carbon storage, making high-demand materials like concrete pivotal to transformative environmental outcomes.
So, what’s the catch?
Producing these materials uses more energy, which could slightly offset the gains. But don't worry, energy emissions weren't modelled in the research paper this publication used, and it looks like we’re still on track.
One thing is that relying on materials already needed for other industries (think energy and food) is seen as one that could cause competition because Biochar’s carbon storage comes at the expense of energy, and mineral wastes like blast furnace slag are critical for cement, adding to the complexity.
That is where the trio of researchers put it that carbon storage depends on material use which is expected to grow as the world population increases.
“If we rolled out every carbon-storing building material alternative at once, the built environment could sequester a whopping 13.8 to 19.3 Gt of CO₂ each year, depending on the carbon content of the materials,” the researchers note.
Assuming material consumption stays constant, by 2100, we could store more than 1200 Gt of CO₂ in our buildings if we go all-in on these alternatives by 2025.
Compare that to the 136.8 Gt of cumulative CO₂ emissions from process-related emissions under a “business as usual” approach, and it’s clear: carbon-storing materials are the superheroes we didn’t know we needed. And here’s the kicker: many of these carbon-storing materials are becoming cost-competitive with traditional ones, thanks to affordable feedstocks like mineral waste and biomass residues. This price drop is fuelling market demand, with more companies jumping on the CO₂-storing bandwagon.
What options are we looking at here?
Low-carbon concrete is one hot spot of innovation. Take Solidia Technologies and Carbon Upcycling, who’ve figured out how to lock CO₂ into cement via carbon mineralisation—slashing CO₂ emissions by up to 70 percent compared to your standard concrete. Meanwhile, BluePlanet and OCO Technology are churning out synthetic carbonate aggregates, which combine industrial waste, alkaline rocks, and CO₂ streams to produce carbon-negative building materials.
Bio-based plastics may have been around since the early 20th Century, but they still only account for one percent of global plastic production.
Do the options inspire confidence?
Yes. The market is shifting as policy changes and the push for a circular bioeconomy expand their use into construction.
Companies like Braskem and Biovyn are pumping out bio-based PVC and polyethylene, while Dow and Mango Materials are tapping waste biomass and methane to reduce land-use impacts. With renewable energy, these materials could even turn carbon-negative, despite the agricultural emissions they come with.
In construction, we're seeing some seriously innovative materials. Take carbonate-based and biomass-based bricks. Orbix, for example, makes calcium carbonate bricks by mineralising CO₂ in steel slag, claiming a 600kg CO₂/tonne reduction.
Asphalt alternatives are also making waves. Avello Bioenergy is swapping out petroleum-derived bitumen for bio-oil-based asphalt, while Avantium, in partnership with Roelof, has created a lignin-based bioasphalt road that could cut GHG emissions by 30–60 percent compared to conventional asphalt. Talk about paving the way for a greener future.
Any roadblocks?
Many carbon-storing materials are in the prototype phase, and traditional materials are hard to beat on price. Carbon mineralisation, which requires concentrated CO₂ and alkaline feedstocks, is held back by expensive direct air capture (DAC).
To make it work, industries like steel manufacturing could provide flue-gas sources rich in CO₂ to enhance economic viability. Though not technically CDR, these methods could store carbon while reducing reliance on geologic reserves.
Bio-based plastics also face their own hurdles.
While conversion technology is there, limited access to biomass is still a bottleneck. Plus, construction’s risk-averse nature means changing material performance could lead to failures, design shifts, or increased environmental impacts from more frequent replacements.
And carbonation-cured materials struggle due to outdated codes, but performance-based standards could open the door for widespread use. And while bio-based plastics are close to fossil-based ones in performance, long-term durability studies are still scarce.
What resources are typically being used?
Olivine and basalt are big players in the carbon sequestration game, but like any good treasure hunt, digging them up efficiently is a challenge. And while we’re swapping materials, scaling biochar is another tall order: 0.4 Mt was made in 2021, but to meet demand, we need 600 Mt, a 2021 Triton Market Research shows.
The materials may be plentiful, but they are not always easy to reach. Mining for minerals like carbonatable cement ingredients is like hunting for buried treasure— deep underground. Southeast Asia and Africa’s surface-exposed deposits could be our best shot at scaling these technologies.
Innovation, resourcefulness, and a dash of geography magic will be needed. The Intergovernmental Panel
on Climate Change (IPCC) AR6 already warns that we need to remove a massive 660Gt of CO₂ for a 1.5°C target and 290Gt for 2°C by 2100, on top of the usual efforts— low-carbon energy, cutting non-CO₂ emissions, and improving efficiency.
Despite growing demand for materials, we’re assuming things stay at 2016 levels with a small increase in wood demand
due to sustainable forestry. IPCC argues that switching to carbon-storing materials could store a whopping 1380,920, or 460 Gt of CO₂ by 2100 (by 2025, 2050, or 2075, respectively)—well over its targets.