The fundamental idea of “primary” and “secondary” data is key in the book and claim world and often overlooked. Unintended data mismatches can disrupt even the most sophisticated practitioners. We often hear people talk of using “actuals” or looking up a “default” from a database. What is that referring to? And are there other ways to discuss data? Below are the differences between primary and secondary data.

1. Primary data refers to a quantified value of a process or activity obtained through direct measurements or refers to calculations based on direct measurements (ISO 14083:2023). Ranging from precise information such as fuel receipts to aggregated values reflecting annual energy consumption, it is the preferred type of data for calculating Scope 1 GHG emissions for transport or logistics site operators and for collecting data from carriers for Scope 3 emissions accounting.
2. Secondary data encompasses all data that is not primary data and can be further categorized into modeled data and default data (see ISO link).
3. Modelled data incorporates primary data and/or GHG emission-relevant parameters of a transport or hub operation. Companies and tool providers use modeled data to estimate energy consumption and emissions based on available information about goods, journey details, vehicle information, and other factors. The accuracy of modeled data depends on the level of detail available, and the modeling assumptions made.
4. Default data is used if better data is not available. Default values represent indicative industry operating practices, provide a general indication of emissions, and can even be useful for niche applications such as identifying emission hotspots. However, default values are inherently dependent upon the assumptions that are used as the inputs to the calculation and so it is critical that those assumptions are fully set out and understood by those who use them – otherwise there is a strong risk of inappropriate application. Hence, relying on default data can increase uncertainty.It is important to specify the source of any default data used and to communicate with partners to gather more specific information that can enhance overall accuracy, as a Community.

In the end, when evaluating a book and claim offering or providing one, it’s fundamental to know your data. Primary data is preferred for emissions calculations that underpin the value chain claim, but it’s understood that a combination of different data types may be necessary.