Embodied carbon
Embodied carbon is the greenhouse gas emissions associated with making, transporting, installing, maintaining, replacing, and disposing of materials and products. In buildings and infrastructure, it highlights the climate impact hidden in concrete, steel, glass, insulation, finishes, and construction work.
What it is
Embodied carbon is the greenhouse gas emissions associated with a product or built asset before, during, and after its use. In construction, it includes emissions from extracting raw materials, manufacturing products, transporting them, building with them, replacing components, and handling demolition or disposal. The term is most often used for buildings and infrastructure because large amounts of concrete, steel, aluminum, glass, asphalt, insulation, and other materials are used before anyone turns on the lights or heats the space.
Embodied versus operational carbon
Operational carbon comes from running a building or asset: heating, cooling, lighting, plug loads, hot water, fuel use, and sometimes refrigerant leakage. Embodied carbon comes from the materials and construction supply chain. As buildings become more energy efficient and electricity grids get cleaner, embodied carbon can represent a larger share of total climate impact. This does not make operational emissions unimportant. It means designers and owners have to manage both at the same time.
Upfront carbon
Upfront carbon is the portion of embodied carbon released before a building or infrastructure project is occupied or used. It usually includes product manufacturing, transport to site, and construction activity. This timing matters. Emissions released today affect the climate immediately, while operational savings may arrive gradually over decades. A design that reduces future energy use can still have a high upfront carbon cost, so teams need to compare timing as well as totals.
Where emissions come from
High-impact sources vary by project, but concrete, steel, aluminum, glass, insulation, asphalt, and interior finishes are common hotspots. Cement production releases CO2 from fuel use and from the chemical conversion of limestone. Steel emissions depend on whether production uses coal-based blast furnaces, scrap-based electric arc furnaces, or lower-carbon processes. Transport and construction equipment can matter too, especially for heavy materials or remote sites. Replacement cycles also count: a low-carbon material that fails early may perform worse over the life of the building.
How it is measured
Embodied carbon is usually estimated through life cycle assessment. A project team defines a functional unit, system boundaries, life cycle stages, data sources, and assumptions. Results are often reported as carbon dioxide equivalent, or CO2e, so different greenhouse gases can be compared in one metric. Environmental product declarations can provide product-specific data, but they are not automatically comparable unless they follow compatible product category rules and assumptions. Generic databases can fill gaps, but they may hide local manufacturing or energy differences.
Ways to reduce it
The biggest reductions often come from building less new material in the first place. Reusing existing structures, designing smaller or more adaptable spaces, avoiding overdesign, and extending service life can cut material demand before product choices even begin. Material strategies include lower-clinker cement, supplementary cementitious materials, optimized concrete mixes, recycled steel, responsibly sourced timber, low-carbon insulation, reuse of structural components, design for disassembly, and procurement rules that ask suppliers for transparent carbon data.
Tradeoffs and accounting
Embodied carbon decisions can create tradeoffs. More insulation may increase embodied carbon but reduce operational energy. Mass timber can store biogenic carbon, but accounting depends on forest management, product lifetime, end-of-life treatment, and whether the wood displaces higher-carbon materials. Good analysis avoids treating any material as automatically good or bad. It compares realistic options for the same function, uses transparent assumptions, and checks whether reductions in one life cycle stage increase impacts somewhere else.
Why it matters
Embodied carbon matters because construction decisions lock in emissions before a building opens. Once concrete is poured and steel is fabricated, those emissions are already in the atmosphere or counted in the supply chain. Lowering embodied carbon can push cleaner materials, better reuse, smarter design, and more honest procurement. It gives climate policy a way to address the physical stuff of buildings and infrastructure, not only the energy they consume later.