Embodied carbon is the total greenhouse gas emissions produced during the extraction, manufacturing, transportation, and construction of building materials. It accounts for roughly 11% of global energy-related carbon emissions, separate from the 28% that comes from actually heating, cooling, and powering buildings once they’re occupied. Together, these two categories mean buildings are responsible for 39% of global carbon emissions, making embodied carbon one of the largest and least-addressed contributors to climate change.
Embodied vs. Operational Carbon
Every building has two carbon footprints. Operational carbon is the easier one to picture: it’s the emissions from running the building day to day. Heating, air conditioning, lighting, plugging in appliances. This is the carbon most people think of when they hear “energy-efficient building,” and it’s the focus of insulation upgrades, solar panels, and smart thermostats.
Embodied carbon is everything that happened before anyone flipped a light switch. It covers the emissions from mining raw ore, firing cement kilns, smelting steel, sawing lumber, trucking materials to a job site, and bolting the whole thing together. It also includes emissions from maintenance, renovation, and eventual demolition. A building labeled “zero carbon” typically means zero operational emissions only. The embodied carbon is locked in before the doors open.
This distinction matters more as buildings become more energy-efficient. When operational emissions shrink thanks to better insulation and renewable energy, embodied carbon makes up a larger share of a building’s total lifetime footprint. For some highly efficient new buildings, the materials and construction can represent half or more of the structure’s total emissions over its lifespan.
Where the Emissions Come From
The construction industry tracks embodied carbon using a standardized lifecycle framework. The stages most relevant to embodied carbon are grouped under “Stage A,” which breaks down into five modules:
- A1: Raw material supply. Mining limestone for cement, extracting iron ore for steel, harvesting timber.
- A2: Transport to the factory. Shipping raw materials to the manufacturing plant.
- A3: Manufacturing. The energy-intensive processes that turn raw materials into usable products like concrete, steel beams, or glass panels.
- A4: Transport to the construction site. Trucking finished materials from the factory to where the building goes up.
- A5: Construction and installation. Energy used by cranes, excavators, and other equipment on site.
Modules A1 through A3 are the biggest contributors and the ones most commonly reported in product environmental disclosures. Manufacturing is where the heaviest emissions concentrate, particularly for materials that require extreme heat. Producing cement, for example, involves heating limestone to around 1,450°C, a process that releases carbon dioxide both from the fuel burned and from the chemical reaction in the limestone itself.
Which Materials Carry the Most Carbon
Not all building materials are equal. Steel and concrete are the two largest sources of embodied carbon in construction, largely because of the enormous volumes used and the fossil fuel intensity of their production. Concrete alone is responsible for about 8% of global CO₂ emissions when you count the entire cement industry.
Timber is dramatically lower. Research comparing structural floor systems found that cross-laminated timber (CLT) slabs emit about 75% less CO₂ than reinforced concrete slabs with equivalent structural performance. Timber-concrete composite systems, which use both wood and concrete together, emitted about 65% less. Wood has an additional advantage: trees absorb carbon dioxide as they grow, so the material stores carbon rather than only releasing it.
That doesn’t mean every project can simply swap concrete for wood. Structural requirements, fire codes, building height, moisture conditions, and cost all factor in. But knowing the carbon gap between materials gives designers a starting point for reducing a project’s footprint.
How Embodied Carbon Is Measured
The primary measurement tool is a Life Cycle Assessment (LCA), which quantifies the environmental impact of a product from raw material extraction through end of life. Manufacturers publish the results in Environmental Product Declarations (EPDs), standardized documents that function like nutrition labels for building materials. An EPD for a specific brand of concrete will list its global warming potential in kilograms of CO₂ equivalent per unit, letting designers compare it directly against competing products.
One of the most widely used digital tools for this comparison is EC3, a free platform developed by the nonprofit Building Transparency. EC3 houses a database of thousands of digitized EPDs and lets project teams input their material quantities from building models or cost estimates, then compare the embodied carbon of different product options side by side. It integrates with design platforms like Autodesk Construction Cloud, Procore, and One Click LCA, so carbon data can feed into decisions during design rather than being calculated after the fact.
Strategies for Reducing Embodied Carbon
The most effective reductions start with using less material in the first place. Optimizing structural designs to eliminate overengineered elements, reusing existing buildings instead of demolishing them, and specifying materials with lower carbon intensity all cut emissions before any new technology enters the picture.
For concrete specifically, several innovations are gaining traction. Carbon capture during manufacturing can inject CO₂ directly into the concrete mix, where it mineralizes and actually strengthens the final product. CarbonCure, a Canadian company, has deployed CO₂ injection systems in factories worldwide, reducing the amount of cement needed while improving concrete strength. In Japan, a product called CO2-SUICOM uses a specialized calcium silicate compound that reacts with carbon dioxide during curing, effectively absorbing CO₂ as part of the hardening process. Supplementary materials like calcined clays and industrial byproducts can also partially replace cement in concrete mixes, cutting the most carbon-intensive ingredient.
Choosing local materials reduces transport emissions. Specifying recycled steel instead of virgin steel avoids the energy cost of mining and smelting from scratch. And in cases where timber can structurally replace concrete or steel, the carbon savings are substantial.
Regulatory Pressure Is Building
For years, embodied carbon flew under the regulatory radar while energy codes focused exclusively on operational efficiency. That’s changing. The European Union’s updated Construction Products Regulation will require manufacturers to declare the global warming potential of their products over the full lifecycle, covering fossil, biogenic, and land-use-related emissions. The EU has also announced a mandatory carbon label for cement, displaying its global warming potential directly on the product. A digital product passport system will eventually cover every product regulated under the new rules, including information on carbon footprint, durability, recyclability, and material composition.
In North America, policies are more fragmented but moving in the same direction. Several U.S. states and cities now require whole-building LCA reporting for large projects, and federal procurement rules increasingly favor low-carbon materials like “Buy Clean” policies for government-funded construction.
Industry Targets for 2030 and Beyond
Architecture 2030, an influential nonprofit that sets voluntary benchmarks for the building industry, has laid out an aggressive timeline. Its 2030 Challenge for Embodied Carbon calls for a 45% reduction in global warming potential by 2025, 65% by 2030, and net zero embodied carbon by 2040. These targets apply to all new buildings, infrastructure, and the materials that go into them.
Hitting those numbers will require changes at every stage of the supply chain. Material manufacturers need to decarbonize production. Designers need to choose lower-carbon alternatives and optimize structures to use less material. Contractors need to minimize waste on site. And the broader industry needs transparent, comparable data to make carbon-informed decisions routine rather than exceptional. The tools and benchmarks exist. The gap is in adoption.