Activity-based: Yook Methodology
A product carbon footprint (PCF) balances the greenhouse gas emissions caused over a product’s life cycle. Its unit is CO2e, which is used to compare and aggregate other greenhouse gases - including methane and nitrous oxide - based on their global warming potential (GWP 100). Yook calculates PCFs using attributional allocation on an (extended) cradle-to-gate basis, which includes materials, manufacturing, packaging and distribution of a product. The use phase is (not yet) covered, since this life cycle stage is usually subject to massive variability and uncertainty due to personal use behavior, country-specific characteristics, and framework conditions. Similarly strong assumptions have to be made for the end of life phase, that’s why it is so far only partially covered by the circular footprint formula (CFF) - if applicable.
The first part of a product’s carbon footprint includes the emissions caused by raw material extraction and processing. Depending on the product this can include agriculture, recycling of pre-used materials (applying CFF) or the production of components, always including their transport and packaging between processing facilities. this means that in some cases, the material part already includes certain production steps for the production of the materials (e.g. for textiles, the yarn, and fabric production from the raw fibers).
For the assessment, Yook extracts the products’ materials or ingredients from the product data, enriches them with Standard Product Data if necessary, and combines them with the associated best-fit emission factors from its own database. This database is constituted from various sources and includes public, licensed, and private databases as well as studies from scientific literature and EPDs (Environmental Product Declarations). To ensure comparability of the data entries, they have been harmonized and assessed with the Reliability Score. Yook's database is continuously expanded and updated.
If primary supplier data is available, a quality score is also assigned and used for the calculation. Yook assists in contacting suppliers and data query, if needed.
In the second part of the PCF, the emissions resulting from the production of a good are quantified. These are mainly caused by the energy demand during production. Production can consist of several process steps at different factories of different suppliers. To calculate the emissions of manufacturing, the total energy and heat consumption of the different processes is determined and then, based on emission factors of the electricity mix, the emissions are calculated. The determination of the energy consumption depends on the data availability. Primary data, including the machine running time and power consumption, is used to directly estimate emissions. Scientific literature complements the data on electricity and heat consumption in manufacturing processes. For the calculation of the emissions based on energy consumption, primary data on the specific energy mix is used if available. Otherwise, the national grid mix is applied for the calculation.
In the third part, the emissions of all transport stages within the system boundaries and the product packaging are assessed together. Transport
Regarding transport, firstly, the transport of raw materials and components from the extraction site to the production sites is considered, if they are not already accounted for in the Emission Factors (EF). Secondly, in the case of two or more production sites, the transportation of components between production sites is taken into account. Lastly, the transportation of finished products from the production site to the warehouse is assessed. Depending on whether the product is transported inter- or intra-continental, we use different emission factors for the means of transport (mostly truck, ship, and plane) and assume average distances for the transport routes when no supplier-specific data is available. The transportation of packaging materials is also considered in Yook's assessment, both for component transportation and final product transportation.
Packaging can be divided into three areas. Primary, secondary, and tertiary packaging. Primary packaging is the packaging needed to wrap the product like the bottle of a detergent, for example. For transportation, further packaging is needed, such as a cardboard box and a pallet. This type of packaging is covered in secondary and tertiary packaging. In the packaging section, Yook calculates the CO2e emissions of the packaging of the components and the final product. If packaging is used for the transportation of raw materials and components, it is included based on available data. If primary data is not available, we use sector-specific standard data in compliance with the product category and dimensions. In the final product packaging, the primary, secondary, and tertiary (transport of the final product to the warehouse) is taken into account in the PCF. Here, the same methodology applies, if primary data is not available, sector-specific average data about typical packaging materials and their weights is used to calculate the emissions based on the product category and dimensions of the product.
Last Mile/ Shipping
The cradle-to-gate footprint is extended by the fourth phase to include two scenarios, based on whether the product is sold online or stationary in retail stores. Here we calculate with average values for distances and transport routes and base our calculation on frequently used assumptions from the scientific literature. For online orders, the return rate is also included in the calculation.
There are generally three limitations to consider when interpreting and using the results:
1. Cradle-to-Gate consideration:
- The use and disposal phases (including disposal of waste products during production as well as secondary packaging) are not calculated, even though they can have a significant GWP effect. This decision is based on the following reasons:
- poor data quality and availability,
- extremely high volatility of possible assumptions,
2. Focus on CO2e emissions:
- Additional impact categories to capture the total damage potential of a product are currently not assessed, although they can have a significant environmental effect and this can lead to unintended burden shifting. That is why Yook is currently working on integrating the other impact categories into the assessment to improve the methodology.
3. Data quality and availability
- A major challenge in PCF calculation and LCA in general is the often very limited availability and quality of suitable data. To make the limitations due to data quality and availability visible and to avoid underestimation of CO2e emissions, Yook has developed the Accuracy Score.
Yook PCF calculations are based on the requirements of the GHG Protocol (Scope 3 Accounting and Reporting Standard; Product Life Cycle Accounting and Reporting Standard), ISO 14067 (CO2 footprint at product level), and the preliminary PEF Guidelines of the EU. However, as these often leave a lot of freedom, we disclose our methodology and create transparency. Where we deviate from recommendations or the standard approach, we explain why. An independent peer review of the methodology and results applied by Yook is possible.