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Glossary · Energy industry & energy transition

Embodied Carbon

Embodied Carbon Embodied emissions Carbon footprint Building materials product life cycle assessment

Embodied carbon refers to the greenhouse gas emissions attributed to a product, building, building component or infrastructure over the material part of its life cycle. Depending on the system boundary, this includes raw material extraction, manufacturing, transport, construction and also maintenance, replacement of components, deconstruction and disposal. It therefore covers emissions that do not arise from heating a building, transmitting electricity or operating a wind turbine, but from physically providing them. A large share of these emissions occurs before the facility is used for the first time. In German, the term "graue Emissionen" is often used. However, a figure is only meaningful once it is clear which life cycle stages it includes.

Embodied carbon is usually stated in kilograms or tonnes of CO₂ equivalents. Different greenhouse gases such as methane or nitrous oxide are converted into a common unit according to their global warming potential. The reference unit varies depending on the object: for buildings it is often the square metre of usable floor area, for building materials the tonne or cubic metre of material, and for energy facilities the kilowatt of installed capacity or the kilowatt-hour generated over the service life. This reference unit is not a minor detail. Values per building, per square metre, per square metre and year, per kilowatt or per kilowatt-hour each convey something different and cannot be compared directly.

Distinction from operational emissions and energy consumption

Embodied carbon must be distinguished from operational emissions. Operational emissions arise during use, for example from a gas heating system, electricity consumption, process heat or fuels. Embodied carbon, by contrast, is contained in the material basis: cement clinker for concrete, steel for load-bearing structures, copper and aluminium for cables, silicon and glass for photovoltaic modules, battery cells, insulation materials, power electronics, transformers, foundations and transport. In a building life cycle assessment, embodied emissions mainly comprise manufacturing and construction, maintenance and replacement, and end of life. Energy and water consumption during operation are reported separately as operational emissions.

This distinction is particularly important for buildings. A highly efficient new building may need little energy in operation and still have high embodied emissions if large amounts of emission-intensive material were used. Conversely, a moderately efficient existing building may perform better in the overall balance than demolition and new construction if the new building requires large quantities of concrete, steel and building services. The climate balance then does not depend only on later electricity consumption or heat demand. What matters is how the operational emissions saved relate to the newly caused manufacturing emissions. Timing also counts: manufacturing emissions occur immediately, whereas operational savings accrue only over decades.

Embodied carbon is also not the same as embodied energy or primary energy. Primary energy describes the energy input before conversion and use, whereas embodied carbon refers to greenhouse gas emissions. A product manufactured in an energy-intensive way can have low emissions if renewable process energy was used. Conversely, a moderate energy input can cause high emissions if coal or natural gas is burned or process-related emissions occur. The best-known example is the calcination of limestone in cement clinker production: the CO₂ is released from the raw material itself, regardless of the fuel used.

Life cycle modules, system boundaries and data quality

How reliable a figure is depends on the system boundary. In the construction sector, the European standards EN 15804 (construction products) and EN 15978 (buildings) divide the life cycle into modules. An overview:

  • A1 to A3, production stage: raw material supply (A1), transport to the factory (A2) and manufacturing (A3). This corresponds to an assessment following the cradle-to-gate principle, i.e. up to the factory gate.

  • A4 and A5, construction stage: transport from the factory to the construction site (A4) as well as installation and the construction process (A5). A1 to A5 are often summarised as upfront carbon.

  • B, use stage: maintenance, repair, replacement and refurbishment (B1 to B5) as well as operational energy and water use (B6, B7). Only B6 and B7 count as operational emissions.

  • C1 to C4, end of life: deconstruction, transport, waste processing and disposal. A to C together form an assessment following the cradle-to-grave principle.

  • D, beyond the system boundary: possible credits and burdens from reuse, recycling or energy recovery. They are reported separately and not offset against the actual building life cycle.

A value for the "embodied carbon of a building" can therefore only be put into context if it is known whether it covers only the manufacture of building materials (A1 to A3) or also the construction process, replacement investments and end of life. It is equally important whether Module D was included. The reference period and the definition of floor area must also be stated.

The data usually come from environmental product declarations (EPDs) or from databases for life cycle assessment. These data are necessary, but they are not naturally given measured values. They are based on assumptions about production processes, the electricity mix at the plant, transport routes, service lives, recycling rates and system boundaries. Generic average values can deviate significantly from manufacturer-specific EPDs. Two methodologically correct values are therefore not automatically comparable, for example if they use different service lives or system boundaries.

For timber, biogenic carbon is added. Timber stores carbon as long as it does not rot or burn. In many assessments, this uptake is booked as a negative value in the production stage and counted again as an emission at end of life, for example upon incineration. Anyone who states only A1 to A3 therefore presents timber products more favourably than the overall balance justifies. Independently of this, it remains to be checked whether the timber comes from sustainable forestry, how long the carbon remains bound and what emissions arise from processing and transport. For concrete, reference is often made to carbonation, i.e. the fact that hardened concrete takes up some CO₂ again over time. The effect is real, but limited and slow. It does not offset the process-related emissions of cement production.

Legal framework in the EU and in Germany

For buildings, the calculation is becoming mandatory in the EU. The recast Energy Performance of Buildings Directive (EU) 2024/1275 (EPBD) requires in Article 7(2) that Member States have the life-cycle global warming potential (GWP) of new buildings calculated and disclosed in the energy performance certificate. This applies from 1 January 2028 to new buildings with more than 1,000 m² of useful floor area and from 1 January 2030 to all new buildings. According to Annex III, the value is stated in kg CO₂ equivalent per m² of useful floor area, for each life cycle stage and over a reference period of 50 years. According to the Directive, this indicator brings together the emissions embodied in construction products and the emissions of the use stage. Member States may provide for exemptions for certain building categories that do not require an energy performance certificate. By 1 January 2027, they are also to submit roadmaps describing the introduction of limit values for the life-cycle GWP of new buildings. This applies to new buildings. Existing buildings are covered by this calculation obligation only to a limited extent, for example through an estimate for buildings of class A+.

The uniform calculation framework is laid down by Commission Delegated Regulation (EU) 2026/52 of 16 December 2025. It replaces Annex III of the EPBD and entered into force on 24 May 2026. It leaves Member States room to integrate their existing national methods. The results are to be reported transparently at least for each life cycle stage. In Germany, a building energy law promulgated in Bundesgesetzblatt 2026 I No. 226 of 28 July 2026 contains a definition of life-cycle global warming potential that refers to Annex III of the EPBD. There, the value is to be stated in kg CO₂ equivalent per m² of reference floor area and year. A German annual value is therefore not comparable with an EU value over 50 years without conversion.

On the product side, the EU Carbon Border Adjustment Mechanism (CBAM) applies to the emissions embodied in imported goods. The definitive phase has applied since 1 January 2026: importers of cement, iron and steel, aluminium, fertilisers, hydrogen and electricity must gradually bear CO₂ costs for the embodied emissions. These are phased in from 2026 to 2033. This covers only part of the embodied emissions of a structure, namely the production of certain basic materials, not the entire life cycle.

Significance in the electricity system

In the electricity system, embodied carbon gains weight because operational emissions fall due to renewable energy, electrification and more efficient facilities. For fossil-fuelled power plants, emissions from fuel combustion usually predominate over the service life. For wind power, photovoltaics, power grids, storage and heat pumps, by contrast, a large share of emissions occurs before use. These facilities cause hardly any direct emissions in operation, but require materials, industrial intermediate products, logistics and installation.

This does not mean equating renewable facilities with fossil-fuelled power plants. A gas-fired power plant causes additional emissions from combustion in every hour of operation. A photovoltaic system causes most of its emissions before the first kilowatt-hour. Compared with fossil-generated electricity, it has usually offset these emissions after a few years, i.e. well before the end of its service life. Exactly how long this takes depends on the place of manufacture and the electricity mix there, on the location, the yield, the service life and the displaced electricity mix.

Embodied carbon is nevertheless important for expansion decisions. The electricity transition requires additional grids, storage, generation facilities, substations, charging infrastructure, electrolysers and conversions in industry, and all of this has a material footprint. Not every additional facility is therefore equally good simply because it later enables low-emission electricity. Capacity utilisation, service life, material intensity, repairability and recyclability matter. And it matters whether the facility actually replaces fossil emissions or merely serves additional demand.

For security of supply and ongoing operation, embodied carbon plays no role. Which power plants run is determined by market bids, schedules and grid-technical requirements, not by the embodied emissions of transformers or lines. In long-term planning, however, the concept is important because different expansion paths require different amounts of material and different supply chains. A system with high load peaks needs more generation, grid and reserve capacity than one that manages demand flexibly. Embodied emissions thus also depend on flexibility, load management and storage strategy.

Typical misinterpretations

A common oversimplification is to call technologies "emission-free" without stating the life cycle boundary. An electric car, a heat pump or a solar system causes no direct CO₂ emissions at the place of use, but their manufacture is not emission-free. Anyone who makes this distinction does not play down their climate impact, but creates the basis for a sound balance.

A second misinterpretation arises when embodied carbon is considered in isolation. High manufacturing emissions alone say nothing about whether a use makes sense in terms of climate policy. What counts for the assessment is the comparison over the entire service life and with a realistic alternative. A battery, too, has embodied emissions. But if it reduces fossil peak load, eases grid bottlenecks or reduces the curtailment of renewable generation, its benefit to the system can clearly exceed the manufacturing emissions. If it is poorly utilised, the balance turns out differently.

The spatial attribution is also often imprecise. Many emissions arise not where a product is used, but where raw materials are extracted and components are manufactured. A country can reduce its territorial emissions and at the same time import emission-intensive intermediate products. Embodied carbon makes this shift visible. Whether emissions are accounted for by place of production, place of consumption or corporate responsibility, however, remains a political and methodological decision.

Economically, embodied carbon depends on prices, procurement rules and regulation. As long as CO₂ costs are only partially priced into supply chains, emission-intensive materials can appear cheap. Public tenders, building standards, product declarations, future limit values for life-cycle GWP and the carbon border adjustment change these incentives. Lower-emission steel or cement, however, only becomes widely established when design standards, liability issues, availability, costs and procurement rules fit together.

Overall, embodied carbon makes the climate balance of material decisions more precise. The concept shows which emissions are already embedded in buildings, facilities and products before they are used. It does not by itself answer which investment is right, and it does not replace a look at operation, service life, function and alternatives. Its strength lies in revealing an easily overlooked system boundary: the climate impact arises not only at the point of consumption, but already with the decision about which infrastructure is built with which materials.

Sources

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Edited by eCMS on 11.11.2026 19:44

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