Carbon footprint or LCA: which approach for an industrial company?

In short:

1. A carbon footprint covers an organisation over one year, an LCA covers a product over its whole life cycle.
2. In France, the regulatory BEGES applies to companies with more than 500 employees (250 overseas), updated every 4 years.
3. LCA follows ISO 14040 and ISO 14044 and assesses several environmental indicators, not just carbon.
4. The two approaches are complementary: the footprint guides strategy, the LCA guides eco-design.

Two approaches, two subjects

Manufacturers starting a decarbonisation process quickly come across two tools: the greenhouse gas emissions inventory and life cycle assessment. They share emission factor databases, but they do not answer the same question.

The organisational emissions inventory

The inventory classifies emissions into three scopes: scope 1 (direct emissions, on-site combustion, processes), scope 2 (emissions from purchased energy) and scope 3 (other indirect emissions: purchases, transport, use and end of life of products sold). In industry, scope 3 is often the largest share.

In France, the regulatory BEGES is mandatory for companies with more than 500 employees in mainland France and more than 250 employees overseas, updated every four years. Companies covered by the European CSRD directive, whose application timeline was revised in 2025, also have broader climate reporting obligations.

The product life cycle assessment

LCA follows a standardised four-phase method:

1. goal and scope definition, including the functional unit used as the basis for comparison;
2. life cycle inventory, which lists material and energy flows;
3. impact assessment, which translates these flows into environmental indicators;
4. interpretation, which identifies the main contributing stages and improvement levers.

In French construction, LCAs feed the environmental and health declaration sheets (FDES) of building products, used in the regulatory RE2020 calculation.

Which approach to start with

For a company getting started, the emissions inventory gives an overall view and points to priority items. If it shows that raw materials or product use weigh heavily, LCA becomes the right tool to act on design. Both approaches rely on emission factors, including ADEME’s Base Empreinte for the French context.

The calculation principle shared by both approaches

Emissions inventories and LCA rely on the same basic logic: multiplying activity data by an emission factor. Activity data describes what was consumed or produced (kilowatt-hours of electricity, litres of fuel oil, tonnes of steel purchased, kilometres travelled). The emission factor converts this quantity into greenhouse gas emissions, expressed in kilograms or tonnes of CO2 equivalent.

The quality of the result therefore depends on two elements:

• the accuracy of activity data, ranging from direct measurement (meters, invoices in quantities) to estimates based on financial amounts;
• the relevance of emission factors, which must match the country, technology and year considered.

When only spending data is available, monetary ratios allow an initial estimate, especially for purchases. They help identify major items but remain imprecise: they do not distinguish a high-performing supplier from a high-emitting one. For major items, the challenge is to move gradually to physical data, then to data provided by suppliers themselves.

The steps of a first emissions inventory

A first emissions inventory generally follows these steps:

1. Define the organisational boundary: which entities and sites are included.
2. Define the operational boundary: which emission sources are covered in scopes 1, 2 and 3.
3. Collect activity data from the departments concerned: energy, purchasing, logistics, travel, waste.
4. Apply emission factors and calculate emissions by item.
5. Assess uncertainties, which can be high for some scope 3 items.
6. Build the reduction action plan, prioritised by the weight of each item and the ability to act on it.

For companies subject to the regulatory BEGES, French regulations require the inventory to be accompanied by a transition plan describing the planned reduction actions. Beyond the obligation, this plan is what gives the exercise its value: an inventory without actions remains a mere observation.

The limits of each approach

Neither approach is perfect, and knowing their limits avoids hasty conclusions.

For LCA, the choice of functional unit deserves particular attention. Comparing two products “per item” makes no sense if their lifetimes differ: the functional unit must express the service provided, for example a function performed over a given period. An LCA intended for public comparative claims must also undergo a critical review, as required by ISO 14044.

Available tools

Depending on the approach and level of detail, several families of tools exist:

• spreadsheets, sufficient for a simple first inventory, provided up-to-date, sourced emission factors are used;
• carbon accounting software, which structures data collection, automates calculations and tracks the reduction trajectory over time;
• LCA software, which relies on life cycle inventory databases such as ecoinvent to model products and processes.

The choice depends on the number of sites, the level of reporting requirements and internal skills. In all cases, the quality of input data matters more than the sophistication of the tool.

Getting teams on board

Carbon accounting and LCA are not purely environmental exercises. Data comes from purchasing, logistics, production, maintenance and design, and reduction levers sit in the same departments. Involving these teams from the data collection stage, and sharing the results with them, turns the inventory into a working tool rather than a report produced by a single person. Engineering teams play a central role, since product design determines a large share of emissions over the life cycle.

From diagnosis to action: the most common levers

Once the main items have been identified, reduction levers in industry fall into a few broad families:

• energy sufficiency and efficiency: tuning installations, tracking compressed air leaks, variable speed drives on motors, insulating heat networks;
• waste heat recovery, from furnaces, compressors or chillers, to supply other uses on site;
• changing the energy mix, for example electrifying some thermal processes or using renewable heat;
• purchasing, with lower-emission or recycled materials and a dialogue with suppliers about their own emissions;
• eco-design, which acts on the mass, materials, lifetime and repairability of products, and where LCA comes into its own;
• logistics, by optimising loads, distances and transport modes.

The emissions inventory helps choose between these levers by showing their relative weight. LCA, for its part, makes it possible to check that a change of material or process really reduces the product’s overall impact, without shifting it to another stage of the life cycle.

Repeating the exercise over time

A single inventory is a snapshot. Its value comes from repetition: measuring emissions on a consistent basis year after year shows whether actions are working and whether the company is on the trajectory it has set. Keeping the same boundaries, documenting changes in methods or emission factors and recalculating the reference year when needed are what make results comparable over time.

In practice, many companies combine both tools: an annual inventory to steer the overall trajectory, and targeted LCAs on the products that weigh most in their footprint.

Frequently asked questions