There are two overarching types of data required in LCA - data that relates to the product (aka in the foreground of the product system) and data that relates to environmental emissions of that product (aka in the background of the product system).

Foreground product data relates directly to the product being assessed, including the inputs and outputs across its life cycle. It is referred to as foreground data because it encompasses everything in the immediate product system, such as the energy (e.g., MJ, kWh) consumed or the materials (e.g., kg, m2) used during production. People also describe this data as ‘physical’ data, as the data relates to the physical properties and attributes of the product. What foreground data is included in the product system is decided during the Goal and Scope phase of your LCA, particularly through exercises that determine the product system (e.g., flow charts).

Accurate foreground product data is essential for quantifying the environmental impacts associated with specific processes, such as calculating the carbon footprint based on energy consumption during production.

Background environmental data translates your product data to environmental impacts. It is referred to as background data because it relates to the broader environmental processes occurring outside the immediate product system, such as CO2 emissions from electricity generation.

This data translates the physical activities in your product's life cycle into measurable environmental impacts, providing essential context for understanding your product's contribution to global environmental outcomes.

Both foreground product and background environmental data can be categorized based on their source and accuracy into three levels.

Primary data is direct data from your production site or suppliers, reflecting the actual operations of your product. This is the most reliable and accurate data, ensuring your LCA results closely represent your product’s environmental impact. Always try to prioritize primary data!

Secondary data is data gathered from external sources, such as databases (e.g., ecoinvent) or industry reports. While less specific, secondary data is valuable for filling gaps and providing a comprehensive view of your LCA.

Proxy data is assumptions or data from similar products or processes used when primary or secondary data is unavailable. Proxy data should only be used when necessary as it is the least accurate, but it can be essential when no other data is available. For instance, if there is no data on a specific chemical, you might estimate its impact with available data on a chemical that resembles yours.

The product components requiring data collection for an LCA depend on the system boundaries defined in the Goal and Scope phase. The system boundaries outline what parts of the product’s life cycle are included in the assessment. If you are following specific regulations or Product Category Rules (PCR), these boundaries may already be predetermined, guiding you in collecting data that aligns with compliance requirements. However, in a typical cradle-to-gate LCA, the assessment generally includes the following product components:

Both (foreground) product data and (background) environmental data, once collected, can be classified as primary, secondary, or proxy data, but the collection process and the level of specificity differs based on the type of data and the LCA's objectives.

For product data, primary data is preferred because it provides accurate, site-specific measurements (e.g., energy use at a facility). Secondary data (e.g., average industry emission factors) and proxy data (e.g., estimates based on similar products) are alternatives when primary data isn’t available. On the other hand, background environmental data often relies on secondary or proxy data due to the broader scope of environmental impacts (e.g., global CO2 emissions from electricity).

Primary data is often preferred because it enhances accuracy, leading to more reliable LCA results, particularly when compliance, verification, or making sustainability claims is a priority. However, the time and effort spent collecting data should match the component's significance to the product's environmental footprint. For key components, such as heavy materials or rare engineering metals, collecting primary data is crucial. Conversely, for less significant components (e.g., small quantities of common materials), secondary or proxy data might suffice. In fact, small components that are difficult to model may not justify the time and effort required to investigate them thoroughly, making secondary or proxy data the more efficient choice.

LCA modeling is an iterative process, so don’t worry if your first version isn’t perfect! As you refine your model, reach out to suppliers for additional data that can help you improve accuracy in future iterations. While primary data offers the best precision, secondary and proxy data remain practical alternatives depending on the material's contribution to the overall environmental impact.

Data collection is the foundation of any LCA and directly determines the accuracy of your results. By capturing the necessary data across the product’s life cycle—whether it’s detailed primary data from production or broader secondary and proxy data—you can create a reliable model of your product’s environmental impact. Understanding the different types of data (foreground product data and background environmental data), the levels of data accuracy (primary, secondary, and proxy), and where data is needed (materials, transport, and production) helps to ensure that your LCA aligns with its intended goals.

The level of detail in your data collection should reflect the importance of each component to the overall environmental footprint of your product. Ultimately, the time and effort invested in collecting accurate data should align with your LCA’s objectives, whether for compliance, sustainability claims, or product improvement.