The Product Lifecycle Stages That Drive the Most Carbon Emissions

The lifecycle stage responsible for the largest share of a product's carbon footprint varies from product to product. For some products, raw material extraction and processing are the largest contributors. For others, manufacturing, energy use during operation, transportation, or end-of-life treatment may account for a larger share.

That variation is why a category average or general rule of thumb does not establish the actual lifecycle emissions of a specific product. The result depends on the product's materials, manufacturing processes, energy requirements, distribution model, expected use, lifetime, and end-of-life pathway. Measuring emissions across the full lifecycle helps identify where the largest impacts occur and where reduction efforts can have the greatest effect.

This blog explains the five product lifecycle stages, examines the factors that influence emissions at each stage, and shows how to identify carbon hotspots across your products.

Product lifecycle stages are the connected phases of a product's life used to organize the processes and greenhouse gas emissions included in a product inventory, commonly referred to as a Product Carbon Footprint (PCF).

The GHG Protocol Product Life Cycle Accounting and Reporting Standard uses five general lifecycle stages to organize product-level greenhouse gas emissions: material acquisition and pre-processing, production, distribution and storage, use, and end-of-life. The standard covers emissions associated with the full product life cycle, including raw materials, manufacturing, transportation, storage, use, and disposal.

The five stages are:

These five stages provide a general structure for organizing a product life cycle. The GHG Protocol notes that companies can further divide or classify stages to better reflect a specific product's life cycle, provided the boundaries are clear and logical and the stages remain consecutive and interlinked.

The stage breakdown is important because a total PCF shows the overall greenhouse gas emissions associated with a product, while results by lifecycle stage help identify where those emissions occur. The GHG Protocol Product Standard is intended to help organizations understand full lifecycle emissions and focus on opportunities to reduce them.

There is no single lifecycle stage that consistently has the largest carbon impact across all products. The result depends on the product's materials, manufacturing processes, distribution, energy or fuel requirements during use, expected lifetime, and end-of-life pathway.

Some general patterns can help provide context:

These are starting points rather than rules. The dominant stage can change significantly depending on the product design, material composition, manufacturing location and processes, energy sources, distribution model, use assumptions, and end-of-life treatment.

Use-phase results are particularly sensitive to assumptions such as expected lifetime, frequency of use, operating energy consumption, and the source of electricity or fuel. Changing these assumptions can change the relative contribution of lifecycle stages.

For this reason, lifecycle-stage contributions should be calculated using a defined product system, unit of analysis (functional unit), system boundary, data sources, and documented assumptions rather than inferred from product category alone.

The sections below examine each lifecycle stage and the factors that can influence its contribution to a product carbon footprint.

The material acquisition and pre-processing stage covers the acquisition of materials, including virgin and recycled materials, and their pre-processing before they enter the production stage. It can include resource extraction, acquisition of recycled materials, processing materials into intermediate inputs, and transportation of material inputs to the production facility.

For manufactured products, this stage often includes processes that take place outside the company's own facilities. Materials and components may pass through several upstream processes before reaching the production site. Understanding these upstream processes is therefore an important part of defining the product system and collecting the data needed for a PCF.

Several factors can influence emissions at this stage:

For products with complex supply chains, material acquisition and pre-processing can therefore represent an important part of the overall product carbon footprint. However, its contribution varies by product and should be determined through the product-level inventory rather than assumed in advance.

Measuring only activities inside the production facility does not capture these upstream processes. A complete product lifecycle assessment needs to account for the relevant material and component inputs that occur before the product enters its production stage.

Production covers the processes that take place from the point where materials or components enter the production site through production of the finished product. It can include energy use, process emissions, material losses, waste treatment and other relevant production activities.

For manufacturers, this stage often contains data that is relatively accessible because companies typically have records for electricity, fuels, production volumes, materials and waste. However, a product carbon footprint requires more than a facility-level total. When a facility produces multiple products, relevant inputs and emissions need to be attributed to the products using an appropriate and documented allocation approach where allocation is required.

The GHG Protocol provides a hierarchy for avoiding or performing allocation and requires companies to apply consistent allocation methods to similar inputs and outputs. The appropriate method depends on the process and the products or co-products involved.

Typical areas to investigate during the production stage include:

Production can therefore be an important source of emissions and an important area for reduction efforts. Its contribution should be determined from the product-level inventory rather than assumed in advance.

The use stage covers emissions associated with using the product during the defined use period. Its importance depends on how the product operates, how frequently it is used, how long it is used, and the energy or fuel required during operation.

For products that consume electricity or fuel during use, the use stage can represent a significant part of the overall footprint. Relevant factors can include:

Use-stage calculations therefore depend on clearly defined assumptions. A change in expected lifetime, operating pattern, energy consumption or energy source can change the calculated contribution of the use stage.

For products where use-phase emissions are significant, product design and energy efficiency can become important areas for reduction.

Distribution and storage cover activities that occur as a product moves from the production facility toward the point where the consumer takes possession. Relevant activities can include transportation, distribution-center operations and storage, including energy requirements for storage conditions where applicable.

The contribution of distribution and storage varies by product and supply chain. Factors such as transportation distance, transport mode, shipment weight, distribution routes and storage requirements can influence the result.

End of life begins after the consumer discards the product. It can include collection, transportation, sorting, recycling, recovery, treatment and disposal, depending on the product system and end-of-life pathway.

End-of-life accounting also requires attention to the treatment of recycled materials. The GHG Protocol Product Standard provides specific approaches for recycling allocation, including the recycled content method and closed-loop approximation method. The selected approach should be documented and applied consistently.

These stages should not be treated as automatically insignificant. Their contribution depends on the characteristics of the product and its lifecycle. A complete product-level assessment considers the relevant processes across all lifecycle stages rather than assuming in advance which stage will have the smallest impact.

There is no universal lifecycle stage that dominates across all product categories. The relative contribution depends on the product system, materials, manufacturing processes, distribution, use profile, lifetime and end-of-life pathway.

This table is a starting point for investigation, not a substitute for calculating the product footprint. The GHG Protocol Product Standard is designed to help organizations understand the full lifecycle and focus on the biggest reduction opportunities rather than assuming a particular stage will always dominate.

If the dominant stage varies by product, the next step is to calculate and review the contribution of each relevant lifecycle stage.

The lifecycle stage responsible for the largest share of a product's carbon footprint depends on the product system and the assumptions used to assess it. Material acquisition, production, distribution and storage, use, and end of life can all contribute to the result, with their relative importance varying across products.

For sustainability, procurement, product and compliance teams, the practical approach is to define the unit of analysis (functional unit) and system boundary, collect relevant data across the lifecycle, document assumptions and allocation methods, and review the results by lifecycle stage.

The GHG Protocol Product Standard is designed to help organizations understand full product lifecycle emissions and identify the areas where reduction efforts can have the greatest impact.