Primary vs. secondary data – What’s the best in LCA?

Zazala Quist
To make an LCA you first need data on your product(s). What's the difference between primary and secondary data in LCA? Which form of data is the best?
Thinking about primary vs secondary data in LCA

To make an LCA of your product(s) you need data. Think of the energy usage for your manufacturing and waste processes, data on your purchased & used raw materials, etc. 

Much data can be found in your own finance or purchase department. But with supply chain data (e.g. purchased raw materials) it’s trickier. How do you get to know the exact raw impact behind the specific materials you purchase? It’s information your suppliers hold.

This raw supply chain data is called primary data. And it’s crucial for credible footprint calculations.

After reading this article you know:

  • The difference between primary and secondary data in LCA
  • Why primary data is so important in LCA

1. What’s the difference between primary & secondary data in LCA?

Primary data: The ‘foreground’ system 

The European Commission defines primary data as directly measured or collected data representative of activities at a specific facility or set of facilities”.

Primary data is (highly) specific and accurate raw data that’s directly collected/measured from main sources. In the case of LCA this covers:

  • raw process- and site-specific data 
  • raw data from suppliers and distributors
  • raw data on the use phase of your product (how your product is used by consumers)

For example, think of the emissions that are directly related to a specific process. Or your exact purchased and used raw materials, your energy use, your waste processes, etc. Or how often your product is used by consumers. You can collect this data using invoice bills (bookkeeping), metered data, manufacturing site visits, surveys, etc.

However, often a large chunk of this data can be found at suppliers or distributors. To get this information, you can request inventory data from these important value chain stakeholders. Yet, the best option is to ask for LCA’s of their products.  

In LCA terms this primary data is called your ‘foreground’ system. It includes all the necessary raw inputs of your product’s lifecycle that are then connected to corresponding impacts in an LCA.

Read more about the specific data you need to make an LCA of a product here

Secondary data: the ‘background’ system

Secondary data, however, are already existing scientific databases collected by previous researchers. The European Commission defines secondary data as “data that is not directly collected, measured, or estimated, but rather sourced from a third-party life-cycle-inventory database

These existing databases are made available for companies to use for their own research. In the case of LCA, this is called the Life Cycle Inventory database. EcoInvent is one of the main LCI databases in our footprint tools.

The LCI database gives you already existing (average) environmental background data on supply chains – without having to really dive into your raw supply chain data. In LCA terms this secondary data is called your ‘background system’. Companies often don’t have access to all their primary data (yet), secondary data then functions to fill these gaps. 

2. Why is primary data so important in LCA?

Because secondary data is more accessible, it allows you to create LCA’s faster – without the hassle of asking suppliers for primary data. It can already give you a very good indication of your impact hotspots. These impact hotspots show you where you need to focus for further sustainability research & improvements.

However, secondary data won’t show the accurate, authentic raw data from your suppliers, making your  LCA more generic and not completely ‘true-to-reality’.  Something that could lead to criticism and potentially greenwashing claims. 

So, using (as much as possible) primary data from suppliers is important as:

  1. It makes your LCA more credible through accurate raw data that’s specific to your footprint study –  instead of relying on averages. 
  2. It provides you with more reliable, authentic and objective footprint insights. This allows for focused and effective sustainable efforts and gives companies more ownership over their LCA’s.

Read our supplier collaboration tips below:

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