Carbon footprint data and methods: primary data, secondary data and the JRC rules

Carbon footprint calculation for batteries is a life cycle assessment exercise governed by the method rules developed by the Joint Research Centre, the JRC, for the Commission, under Article 7 and Annex II of Regulation (EU) 2023/1542. The JRC rules for EV batteries, for rechargeable industrial batteries without external storage, and, in draft form, for LMT batteries, build on the Product Environmental Footprint method and the battery Product Environmental Footprint Category Rules, and set out how the footprint is calculated, which data must be primary, how allocation is handled, and how verification is performed.

The method is the difference between a comparable footprint and a number. Two footprints calculated by different methods, with different boundaries and different data, cannot be compared, however similar the numbers look.

What is primary data and what is secondary data?

Primary data, also called company specific data, is data collected by the operator for the processes it controls or directly influences: energy use at the manufacturing plant, material inputs for the battery model, yields, scrap rates, and transport for the foreground system. Secondary data is data from databases and literature for background processes: extraction and processing of raw materials, production of chemicals, electricity grid mixes, and transport networks. The JRC rules require primary data for defined foreground processes, including battery manufacturing and, where the rules so provide, cell production, because those processes dominate the footprint and vary most between plants. Secondary data must come from datasets that comply with the method, with the dataset version and reference stated. A calculation that uses secondary data for a foreground process where primary data is required does not meet the method, even when the secondary data is of high quality. Data quality is judged against the method requirement, not in the abstract.

How are allocation and energy handled?

Allocation decides how emissions are shared between co products, between a battery and a recycling output, and between the battery and other products from a shared process. The JRC rules set allocation rules for defined situations, including the treatment of recycled content and the end of life stage, so that the same material flow is not counted twice and is not omitted. Energy handling decides how electricity is accounted for: the electricity mix, the use of guarantees of origin or supplier specific mixes where the method allows them, and the treatment of on site generation. Electricity is often a major contributor to the battery footprint, and the electricity accounting rule can change the result materially. A declaration that does not state the electricity accounting approach, the mix used, and the period covered, leaves a reader unable to judge whether two footprints used the same energy basis. The method reference and the declaration breakdown should allow that judgement to be made.

How does the JRC method build on the Product Environmental Footprint?

The Product Environmental Footprint, or PEF, method is the Commission life cycle method that provides the general framework: goal and scope, inventory, impact assessment, and interpretation, with category rules that fix choices for a product group. The JRC battery rules are the battery specific application of that framework, fixing the functional unit, the system boundary, the data requirements, the allocation rules, and the verification approach for batteries. The relationship matters for a reader, because a footprint calculated by a generic life cycle assessment under ISO 14040 and ISO 14044, without the battery category rules, is not the same as a footprint calculated under the JRC rules, even when the same inventory data is used. The declaration must name the method it follows, and a reader comparing footprints must check that the method matches. A generic life cycle assessment can be a useful internal study. It is not an Article 7 declaration unless it follows the prescribed method and format.

What does the data table illustrate?

How are data gaps and proxies handled?

Data gaps are handled by the method rules for proxies, defaults and data quality, not by invention. Where primary data is unavailable for a required process, the method may allow a defined default or a proxy, with the use of the proxy stated and the data quality assessed. A proxy used without a statement is a hidden assumption. A default used where primary data was available is a missed requirement. The calculation record should list each data gap, the proxy or default used, the reason, and the effect on the result where the method requires a sensitivity or data quality statement. A calculation that presents a single precise number with no data quality information overstates the certainty of the result. Life cycle results carry uncertainty from data, from allocation choices, and from the expected service life assumption, and the declaration should allow a reader to see the basis on which the number was produced.

What limits apply to method claims?

A method claim states that a footprint was calculated by the JRC rules and the delegated act methodology. It does not state that the footprint is accurate to the last decimal, that the data was complete, or that the battery is low carbon. Accuracy, completeness and merit are separate judgements, requiring inspection of the calculation record and the verification. This guide gives general educational information only and does not give legal advice for a particular battery, calculation or declaration.