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Cradle-to-Grave

Cradle-to-grave life cycle assessment Carbon footprint product life cycle disposal recycling system boundary

In life cycle assessment (LCA), cradle-to-grave refers to a system boundary. It considers the entire life cycle of a product or facility, from raw material extraction to final disposal. Literally, the term means "from the cradle to the grave". It denotes an accounting approach that does not stop at the factory gate, at the point of sale or at the start of use. Accordingly, the standard DIN EN ISO 14040 defines the life cycle as consecutive and interlinked stages, from the acquisition or generation of raw materials to final disposal.

What is included

A cradle-to-grave assessment typically covers raw material extraction, intermediate products, manufacturing, transport, packaging, installation, use, maintenance, repair, replacement of components, dismantling, recycling, energy recovery and waste treatment. Which processes are actually taken into account in a given case depends on the research question, the available data and the method. Methodologically, such analyses usually follow the standards ISO 14040 and ISO 14044. According to these, a life cycle assessment consists of four phases: definition of goal and scope, life cycle inventory analysis, life cycle impact assessment and interpretation. The system boundary is set in the first phase. It depends on the object of study and the purpose of the study and must be carefully documented.

For construction products, the European standard EN 15804 specifies the life cycle in information modules. A1 to A3 cover the production stage, A4 and A5 the construction stage, B1 to B7 the use stage including maintenance, replacement and operational energy, and C1 to C4 the end of life. A cradle-to-grave declaration covers modules A, B and C. Module D stands for credits and burdens beyond the system boundary, for example through reuse or recycling. It is reported separately. This breakdown clearly shows that in practice "cradle-to-grave" means a specifically defined list of modules and not merely a general buzzword.

Functional unit as the reference quantity

What matters for the assessment is not the product as an object but the functional unit. Life cycle assessment models the life cycle as a product system that fulfils one or more defined functions. The functional unit determines what the environmental impact is related to. For a battery storage system this can be one kilowatt hour delivered over its lifetime, for a vehicle one passenger kilometre, for a heating system one delivered kilowatt hour of heat. Without a functional unit, products with different lifetimes, utilisation and performance can hardly be compared in a meaningful way. The EU Battery Regulation uses exactly such a quantity for the carbon footprint of batteries: kilograms of CO₂ equivalent per kilowatt hour of the total energy that the battery system delivers during its expected service life.

Distinction from cradle-to-gate and cradle-to-cradle

Cradle-to-gate ends at the factory gate or at a defined delivery point. In EN 15804 this corresponds to modules A1 to A3. This boundary is often suitable for supply chains, industrial intermediate products and procurement decisions. However, it says little about the impacts during use. For products with high energy consumption in operation, the difference can be large. A device with lower manufacturing emissions can perform worse over its service life if it operates inefficiently. Conversely, elaborate manufacturing can pay off if the product permanently saves energy or emissions in operation. If a cradle-to-gate value and a cradle-to-grave value are directly compared, this is not a valid comparison.

Cradle-to-cradle, by contrast, refers to a design concept. Here, materials are meant to return after use, as far as possible as raw materials, into technical or biological cycles. Cradle-to-grave is initially only an accounting boundary, not a circular strategy. Such an analysis can take recycling into account, but does not presuppose a closed loop. The term is therefore analytical and not normative: it defines what is counted, not what counts as good product design.

Relevance for the electricity system

For the electricity system, cradle-to-grave is important because many technologies shift their environmental impact over time. Photovoltaic modules, wind turbines, battery storage systems and electrolysers cause a large part of their emissions and resource consumption before the first hour of operation. In operation, they usually have only low direct emissions. For other components the reverse is true: in transformers, cables or inverters, electrical losses over decades can shape the balance. For electric vehicles and heat pumps, the use phase depends strongly on the electricity used. Anyone who evaluates only the use phase ignores manufacturing, raw materials and disposal. Anyone who evaluates only manufacturing overlooks the fuel consumption and emissions avoided later.

The use phase is often the most uncertain part of the assessment. For an electric car, it depends on mileage, service life, battery ageing, charging losses and the electricity mix. For a heat pump, the seasonal performance factor, building standard, flow temperature and the type of electricity generation are decisive. For a battery storage system, the number of cycles, efficiency, operating profile and the question of whether it mainly makes renewable electricity more usable or predominantly exploits price differences on the market all matter. Cradle-to-grave results are therefore not timeless properties of a product, but apply to a specific use scenario.

Life cycle in law: not always complete

When legal texts speak of a "life cycle", this does not automatically mean a complete cradle-to-grave boundary. One example is the EU Battery Regulation (EU) 2023/1542. It requires a declaration on the life cycle carbon footprint for electric vehicle batteries, for rechargeable industrial batteries with a capacity of more than 2 kWh and for batteries for light means of transport. According to the recitals, however, the use phase is excluded, because manufacturers cannot directly influence it. An exception applies only if decisions at the design stage demonstrably affect the use phase. Anyone comparing such values with a classic cradle-to-grave study must be aware of this deviation. The precise calculation rules and application deadlines are set through delegated acts and implementing acts.

Modelling decisions and common misunderstandings

Cradle-to-grave is often understood as the definitive truth about the climate impact of a product. Life cycle assessments, however, rely on modelling decisions. These include assumptions about service life, utilisation, future electricity generation, recycling rates, transport routes and the allocation of burdens to by-products. For metals, for example, it is disputed how credits for recycling should be applied. EN 15804 therefore reports them separately in module D, so that they do not unnoticeably improve the main result. For long-lived facilities, it matters whether calculations use today's or an expected future electricity mix, and whether average or marginal emission factors are used. Different assumptions can lead to different results without any of the analyses thereby being worthless. A comparison only becomes robust when system boundaries, data sources and assumptions are disclosed.

Another misunderstanding is to equate cradle-to-grave with a single CO₂ figure. The system boundary defines which life cycle phases are covered. Which environmental impacts are assessed is decided independently of this, through the impact categories. Besides the climate impact of greenhouse gases, a life cycle assessment can also depict resource consumption, water consumption, acidification, particulate matter formation, land use or toxicity. A pure carbon footprint does not capture these impacts, even if it covers the entire life cycle. Especially for batteries, photovoltaics, power electronics and grid expansion, raw materials, extraction conditions and recyclability are important issues. They only become visible if the analysis includes further impact categories accordingly.

Institutional and economic role

Institutionally, cradle-to-grave plays a role wherever product rules, public procurement, funding programmes, sustainability reports or environmental product declarations draw on life cycle data. Companies use such analyses to assess supply chains, make material decisions or substantiate emission reductions. For regulation and market design, it is important that the rules deliver comparable results. If manufacturers use different system boundaries, figures easily become advertising tools instead of bases for decisions. Comparability arises through clear product categories, uniform data requirements and traceable requirements on recycling and the use phase. The module structure of EN 15804 or the harmonised calculation rules of the Battery Regulation serve this purpose, for example.

Economically, cradle-to-grave shifts the focus from acquisition costs to life cycle costs and life cycle impacts. A product may be more expensive to acquire but need less energy in operation, last longer or be easier to repair. In the electricity system this applies, for example, to low-loss transformers, more durable cables, more efficient inverters or modular storage components. The environmental balance then depends not only on material input but also on losses, maintenance, replacement cycles and dismantling. A cheap component can become expensive if it has to be replaced earlier or causes higher electrical losses over the years.

Limits of the method

Cradle-to-grave does not automatically indicate which decision is right in a specific case. The method describes impacts along a defined chain. It does not replace an assessment of security of supply, grid compatibility, availability, price risks or strategic dependencies. A battery storage system can cause emissions in the life cycle assessment and at the same time provide valuable flexibility for the electricity system. An overhead line or an underground cable causes material and construction emissions and can nevertheless help to integrate renewable electricity better. The ecological balance is an important part of the decision, but sits alongside technical and institutional requirements.

The concept is particularly useful when debates get stuck on a system boundary that is too narrow. For electric vehicles, often only battery manufacturing is considered, or only emission-free operation at the tailpipe. For heat pumps, sometimes only the electricity consumption is seen, without taking the replaced fossil heat into account. For photovoltaics, manufacturing is occasionally emphasised without counting the amount of electricity generated over decades. Cradle-to-grave requires using the same boundary and the same functional unit for all options compared. Only then does it become visible whether a technology actually avoids emissions, merely shifts them in time or causes them elsewhere.

Used precisely, cradle-to-grave is neither an advertising claim nor a quality seal, but an accounting boundary. Its value lies in considering manufacturing, use and end of life together and in disclosing the assumptions made. For products and facilities in the electricity system, this perspective is particularly valuable because material input, operating phase, electricity mix, service life and recycling are closely interlinked. A good cradle-to-grave analysis makes these interrelationships traceable, without deriving a complete system assessment from a single indicator.

Sources

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Edited by eCMS on 11.11.2026 18:13

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