Embodied carbon in buildings: what it is, how to measure it, and why it matters

The built environment accounts for roughly 37% of global energy-related CO2 emissions, and approximately 11% of that total originates not from heating, cooling, or lighting but from the materials and construction processes themselves. According to the United Nations Environment Programme's 2024 Global Status Report for Buildings and Construction, embodied carbon from building materials reached 3.6 GtCO2 in 2023, a figure that has remained stubbornly flat even as operational energy efficiency improves. With over 230 billion square meters of new floor area expected globally by 2060, the carbon locked into concrete, steel, aluminum, and glass at the moment of construction represents a climate liability that cannot be retrofitted away. Addressing embodied carbon is no longer optional; it is the next frontier in decarbonizing the built environment.

Why It Matters

Operational carbon, the emissions from running a building over its lifetime, has dominated sustainability discussions for decades. Building codes, energy ratings, and retrofit programs have driven meaningful reductions in heating, ventilation, and air conditioning (HVAC) energy use. Yet as operational efficiency improves, embodied carbon's share of a building's total lifecycle emissions grows proportionally larger. For high-performance new buildings designed to net-zero operational standards, embodied carbon can represent 50% to 80% of total lifecycle emissions over a 60-year period (World Green Building Council, 2024).

The timing problem makes embodied carbon uniquely urgent. Operational emissions accrue over decades and can be reduced through equipment upgrades, grid decarbonization, and behavioral changes. Embodied emissions, by contrast, are released upfront, primarily during material extraction, manufacturing, and construction. Once a concrete foundation is poured, its carbon footprint is permanently locked in. Given that scientists estimate the world must halve emissions by 2030 to limit warming to 1.5 degrees Celsius, the upfront carbon released in the next five years of construction will significantly shape whether those targets are achievable.

Regulatory pressure is accelerating rapidly. The European Union's Level(s) framework requires lifecycle carbon assessment for public buildings. France's RE2020 regulation, effective since 2022, imposes binding embodied carbon limits on new construction that tighten every three years. In the United States, the Federal Buy Clean Initiative mandates Environmental Product Declarations (EPDs) for construction materials used in federally funded projects. By 2025, over 20 national and subnational jurisdictions had adopted or proposed embodied carbon disclosure or limit requirements (Carbon Leadership Forum, 2025).

Key Concepts

Lifecycle Stages

Embodied carbon is measured across defined lifecycle stages established by EN 15978 and ISO 21930. Understanding these stages is essential for accurate accounting:

A1 to A3 (Product Stage) covers raw material extraction, transport to the factory, and manufacturing. This stage typically accounts for 60% to 80% of total embodied carbon and includes the calcination of limestone in cement production, the reduction of iron ore in steelmaking, and energy consumed during fabrication.

A4 to A5 (Construction Stage) includes transport of finished materials to the building site and on-site construction activities such as crane operation, welding, and formwork. This stage usually contributes 5% to 15% of embodied carbon.

B1 to B5 (Use Stage, Embodied) captures emissions from maintenance, repair, replacement, and refurbishment of building components over the service life. Facade recladding, roof membrane replacement, and interior fit-out refreshes all contribute. This stage can add 10% to 30% depending on building type and replacement cycles.

C1 to C4 (End-of-Life Stage) accounts for demolition, waste transport, processing, and disposal. Buildings demolished and sent to landfill carry higher end-of-life carbon than those deconstructed for material reuse.

D (Beyond the Building Lifecycle) credits potential benefits from material reuse, recycling, or energy recovery. Stage D is reported separately and remains contentious because it relies on assumptions about future recycling rates and markets.

Environmental Product Declarations

An Environmental Product Declaration (EPD) is a standardized, third-party-verified document that quantifies the environmental impacts of a specific product across its lifecycle. Governed by ISO 14025 and EN 15804, EPDs provide the data inputs needed for whole-building lifecycle assessment. A single EPD reports global warming potential (GWP) in kilograms of CO2 equivalent per functional unit, such as one cubic meter of concrete or one metric ton of structural steel.

The number of construction EPDs has grown rapidly. EC3 (the Embodied Carbon in Construction Calculator), developed by Building Transparency, contained over 130,000 EPDs as of early 2026, up from approximately 90,000 in 2023 (Building Transparency, 2026). However, EPD availability remains uneven across geographies and product categories. Insulation, cladding, and interior finish products lag behind structural materials in EPD coverage.

Whole-Building Lifecycle Assessment

Whole-building LCA (WBLCA) aggregates the embodied carbon of every material in a building across all lifecycle stages to produce a total carbon footprint measured in kgCO2e per square meter. Software tools such as One Click LCA, Tally (integrated with Autodesk Revit), and the open-source ATHENA Impact Estimator enable designers to model embodied carbon during the design phase when material substitution decisions have the greatest impact.

A WBLCA performed at the concept stage can identify that structural systems typically contribute 40% to 60% of a building's total embodied carbon, with concrete and steel alone often accounting for over 50%. This insight allows design teams to prioritize interventions where they deliver the greatest reductions.

How It Works

Measuring embodied carbon follows a structured workflow. First, the design team defines the scope: which lifecycle stages to include (A1 to A3 at minimum, ideally A1 to C4), the reference study period (typically 50 or 60 years), and the building elements in scope (structure, envelope, interiors, and sometimes site work).

Second, the team develops a bill of materials from structural and architectural models, quantifying every significant material by mass or volume. BIM (Building Information Modeling) software accelerates this step by extracting material quantities directly from the digital model.

Third, each material quantity is matched to an EPD or generic lifecycle inventory dataset. Product-specific EPDs provide the most accurate data, while industry-average EPDs or database values serve as proxies when specific data is unavailable. The choice between product-specific and generic data can shift results by 20% to 40% for carbon-intensive materials like concrete (One Click LCA, 2025).

Fourth, the tool calculates total embodied carbon across all lifecycle stages and reports results in kgCO2e per square meter of gross floor area. Results are benchmarked against reference buildings of similar typology, climate zone, and program. The Carbon Leadership Forum's CLF Baseline Database and the RIBA 2030 Climate Challenge targets provide widely used benchmarks.

Finally, the design team iterates, testing material substitutions (lower-carbon concrete mixes, mass timber instead of steel, recycled content aluminum), structural optimization (reducing material quantities through efficient design), and specification changes to identify the combination that meets both performance requirements and carbon targets.

What's Working

Low-carbon concrete is scaling commercially. Concrete accounts for roughly 8% of global CO2 emissions, making it the single largest material contributor to embodied carbon. Producers including Holcim, CEMEX, and Heidelberg Materials now offer blended cements using supplementary cite cite materials (SCMs) such as ground granulated blast furnace slag, fly ash, and calcined clay. Holcim's ECOPact range, launched globally, reduces embodied carbon by 30% to 100% compared to standard concrete. By 2025, ECOPact represented over 15% of Holcim's net sales in ready-mix concrete across 19 markets (Holcim, 2025). LC3 (Limestone Calcined Clay Cement) technology, developed at EPFL, reduces clinker content by up to 50% and is being deployed commercially in India, Colombia, and several African countries.

Mass timber is displacing steel and concrete in mid-rise construction. Cross-laminated timber (CLT) and glue-laminated timber (glulam) store carbon rather than emit it. Skanska's Sara Kulturhus in Sweden, completed in 2021 at 20 stories, demonstrated that mass timber high-rises can achieve 40% to 50% lower embodied carbon than equivalent concrete and steel structures. Sidewalk Labs' 35 Hudson Yards in Toronto and the Ascent Tower in Milwaukee (25 stories, completed 2022) further validated mass timber's structural viability. The global CLT market reached $1.8 billion in 2024 and is projected to exceed $3.5 billion by 2030 (Mordor Intelligence, 2025).

Digital tools are democratizing measurement. Building Transparency's EC3 tool, freely available online, allows any project team to compare the embodied carbon of thousands of construction products using EPD data. One Click LCA reports that over 30,000 projects across 170 countries have used its platform as of 2025. Tally's integration with Revit enables architects to assess embodied carbon without leaving their design environment. These tools have reduced the time required for a whole-building LCA from weeks to hours, making embodied carbon assessment feasible even on projects without dedicated sustainability consultants.

What Isn't Working

Data gaps undermine accuracy. While EPD availability for structural materials (concrete, steel, rebar) has improved substantially, many product categories remain poorly covered. Mechanical, electrical, and plumbing (MEP) systems, which can contribute 10% to 20% of total embodied carbon, have very few EPDs available. Regional coverage is also uneven: North America and Europe have relatively robust EPD ecosystems, while Africa, South America, and much of Southeast Asia rely on generic or proxied datasets that may not reflect local manufacturing processes.

Inconsistent methodologies complicate comparison. Different LCA tools, databases, and standards can produce divergent results for the same building. Variations in system boundaries, reference study periods, biogenic carbon accounting methods, and end-of-life assumptions make it difficult to compare embodied carbon claims across projects or jurisdictions. A 2024 study by the Royal Institution of Chartered Surveyors (RICS) found that embodied carbon estimates for the same building could vary by up to 30% depending on the tool and dataset used.

Cost premiums persist for some low-carbon materials. While low-carbon concrete often carries minimal price premiums (0% to 5% in competitive markets), mass timber can cost 5% to 15% more than conventional structural systems at current scale. Green steel produced via hydrogen direct reduction remains 20% to 40% more expensive than blast furnace steel, though costs are declining. These premiums, combined with conservative engineering practices and unfamiliar supply chains, slow adoption particularly in cost-sensitive commercial development.

Regulation lags behind ambition. Despite growing policy momentum, most jurisdictions still lack mandatory embodied carbon limits. Disclosure requirements are more common but do not compel reductions. Even in France, where RE2020 sets binding limits, enforcement mechanisms are still maturing. In the United States, embodied carbon policy remains fragmented across state and municipal levels, with no federal performance standard in place as of early 2026.

Key Players

Established Leaders

• Holcim - Global cement and building materials producer, leading low-carbon concrete (ECOPact) commercialization
• Heidelberg Materials - Major cement manufacturer investing in carbon capture at production facilities
• ArcelorMittal - World's largest steelmaker, piloting hydrogen-based steelmaking (XCarb initiative)
• Skanska - Construction firm pioneering mass timber and embodied carbon reduction in major projects

Emerging Startups

• CarbonCure Technologies - Injects captured CO2 into concrete during mixing, sequestering carbon permanently
• Brimstone - Produces carbon-negative Portland cement from calcium silicate rock instead of limestone
• Material Mapper - Digital platform for tracking and reusing salvaged building materials

Key Investors and Funders

• Breakthrough Energy Ventures - Investing in low-carbon cement, steel, and construction technologies
• LKAB and Hybrit - Joint venture driving fossil-free steel production in Sweden
• U.S. General Services Administration (GSA) - Driving demand through Buy Clean procurement requirements for federal buildings

Sector-Specific KPI Benchmarks

KPI	Low Performer	Median	High Performer	Unit
Upfront embodied carbon (A1 to A5), office building	>800	500 to 600	<350	kgCO2e/m2
Upfront embodied carbon (A1 to A5), residential	>600	350 to 450	<250	kgCO2e/m2
Whole-life carbon (A1 to C4, 60 yr), office	>1,500	900 to 1,100	<600	kgCO2e/m2
Structural system share of total embodied carbon	>70%	45% to 55%	<35%	% of total
EPD coverage rate in material specifications	<20%	40% to 60%	>80%	% by mass
Recycled content in structural steel	<30%	60% to 80%	>90%	% by mass
Cement clinker ratio	>90%	70% to 80%	<55%	% clinker

Action Checklist

• Establish an embodied carbon budget at the project brief stage, setting kgCO2e per square meter targets aligned with RIBA 2030 or LETI benchmarks for the relevant building typology
• Require product-specific EPDs for all major structural and envelope materials in procurement specifications, with preference given to products demonstrating below-industry-average GWP
• Conduct a whole-building LCA at concept design, schematic design, and construction documentation stages using tools such as One Click LCA, Tally, or EC3 to track progress against targets
• Specify low-carbon concrete mixes with reduced clinker content, using SCMs such as slag, fly ash, or calcined clay, targeting a minimum 30% reduction from baseline GWP
• Evaluate mass timber, recycled steel, and other low-carbon structural alternatives early in design when material substitution has the greatest impact on total embodied carbon
• Design for disassembly by using mechanical connections, standardized components, and material passports to enable future reuse and reduce end-of-life (Stage C) carbon
• Benchmark final results against the CLF Baseline Database, RICS whole-life carbon benchmarks, or relevant regional databases and publish findings to contribute to industry knowledge

FAQ

Q: What is the difference between embodied carbon and operational carbon? A: Operational carbon refers to the emissions generated by running a building over its lifetime, including energy for heating, cooling, lighting, and plug loads. Embodied carbon covers the emissions from manufacturing, transporting, installing, maintaining, and eventually demolishing building materials. As buildings become more energy-efficient and electrical grids decarbonize, embodied carbon represents an increasing share of total lifecycle emissions, often exceeding 50% for high-performance new construction.

Q: How much can embodied carbon be reduced with current technologies? A: Studies and pilot projects demonstrate reductions of 30% to 50% using commercially available strategies: low-carbon concrete mixes, mass timber structural systems, recycled steel, optimized structural design, and local sourcing. Emerging technologies such as carbon-cured concrete, green hydrogen steel, and bio-based insulation materials could enable reductions of 50% to 80% at scale. The World Green Building Council's target calls for 40% reduction in embodied carbon by 2030.

Q: Are EPDs required by law? A: EPD requirements vary by jurisdiction. France's RE2020 mandates lifecycle carbon assessment (which requires EPD data) for all new residential buildings. The EU's Construction Products Regulation revision (expected to take full effect by 2028) will require EPDs for many construction product categories. In the United States, the Buy Clean California Act and the federal Buy Clean Initiative require EPDs for steel, concrete, glass, and asphalt used in public projects. Many green building certifications, including LEED v4.1, award credits for using products with EPDs.

Q: Which building materials contribute the most embodied carbon? A: Concrete and steel together typically account for 50% to 70% of a building's total embodied carbon. Cement production alone is responsible for roughly 8% of global CO2 emissions due to the calcination of limestone. Aluminum, glass, insulation, and interior finishes contribute smaller but significant shares. MEP systems and fit-out materials are often underestimated because they lack EPD coverage.

Sources

• United Nations Environment Programme. (2024). "2024 Global Status Report for Buildings and Construction." https://www.unep.org/resources/report/global-status-report-buildings-and-construction-2024
• World Green Building Council. (2024). "Bringing Embodied Carbon Upfront." https://worldgbc.org/advancing-net-zero/embodied-carbon/
• Building Transparency. (2026). "EC3 Tool: Embodied Carbon in Construction Calculator." https://www.buildingtransparency.org/ec3/
• Carbon Leadership Forum. (2025). "Policy Resources: Embodied Carbon in Building Codes." https://carbonleadershipforum.org/embodied-carbon-policy/
• Holcim. (2025). "ECOPact: Net-Zero Concrete." https://www.holcim.com/what-we-do/ready-mix-concrete/ecopact
• RICS. (2024). "Whole Life Carbon Assessment for the Built Environment." https://www.rics.org/profession-standards/rics-standards-and-guidance/sector-standards/construction-standards/whole-life-carbon-assessment
• Mordor Intelligence. (2025). "Cross-Laminated Timber Market: Growth, Trends, and Forecasts." https://www.mordorintelligence.com/industry-reports/cross-laminated-timber-market
• One Click LCA. (2025). "Global Benchmarks for Embodied Carbon in Construction." https://www.oneclicklca.com/