It is equally important to review the assumptions, data sources, and limitations described in the document, as manufacturers may approach these differently depending on product characteristics, production methods, and intended use. This information is not only use for interpreting LCA results but also for ensuring alignment with internal sustainability reporting standards. By focusing on relevant life cycle stages and consistent reference units, readers can quickly extract insights that matter for informed design and purchasing decisions.
So, let’s dive into the life of a product, broken down into these helpful modules to really illustrate the existence of a product. It’s the circle of life for a product and it begins at:
The Product and Construction Process Stage (A1-A5)
A1–A3: The Environmental Impact of Manufacturing
- A1 – Raw material supply: Extraction and processing of materials.
- A2 – Transport: Delivery of raw materials to the manufacturing site.
- A3 – Manufacturing: Energy use, water consumption, and production processes.
These stages are crucial for understanding material choices and production efficiency. They are typically based on primary data from suppliers and production sites, while later stages are often modelled using recognised life cycle assessment scenarios.
A4–A5: Transport and Installation
- A4 – Transport to the building site
- A5 – Installation (including auxiliary materials and energy use where relevant)
These capture the impacts associated with delivering the product to the construction site and its installation.
When the product goes to work (B1-B7)
B1–B5: Use, Maintenance, Repair, and Replacement
These sub-modules include impacts from normal use, routine maintenance, repairs, replacement of components that do not last the full reference service life, and refurbishment where applicable. They illustrate how product durability, maintenance requirements, and component lifespan influence environmental performance over time.
B6: Operational Energy Use
B6 covers energy consumption during the operational life of the product. For HVAC systems, this phase often represents the largest share of total life cycle impacts. When interpreting results, it is essential to consider both the reference service life and the functional unit.
Quick example: Two products with the same daily energy consumption but different service lives will show different total impacts in B6. The product with the longer service life may have higher total impacts, but when recalculated annually, it is often the more sustainable choice, as manufacturing impacts are spread over a longer use period.
B7: Operational Water Use
B7 includes water consumption during the use phase, if relevant for the product.
The final chapter (C1-C4)
Module C covers environmental impacts associated with the end-of-life stage, including deconstruction, transport of waste materials, waste processing, and final disposal (sub-modules C1–C4).
Impacts in this module are strongly influenced by material choice and end-of-life scenarios. Materials that can be reused or recycled generally reduce environmental impacts, while disposal via landfill or incineration without energy recovery increases the overall burden. Effective circular design and material selection are therefore key to lowering end-of-life impacts.
Module D: Benefits and Loads Beyond the System Boundary
Module D accounts for potential environmental benefits or burdens beyond the system boundary, including reuse, recycling, or energy recovery. These results are reported separately from Modules A–C and highlight the potential value of recovered materials and resources in supporting a circular economy
Why EPD comparisons aren’t always straightforward
While EPDs are designed to provide transparency, direct comparisons between products from different manufacturers can be challenging. Why?
- Different reference units (e.g. per product vs per performance over time)
- Different system boundaries and use scenarios
- Different versions of the EN 15804 standard (A1 and the updated version A2)
So, for example, environmental impacts may be expressed using different reference units. Some EPDs relate impacts to a specific level of performance over a defined service life, while others report impacts per product unit. Even when products serve a similar function, such differences can make direct comparisons misleading, as they may not reflect the same level of performance or service provided. Additionally, manufacturers may assume different use scenarios or apply different methodological choices for the use phase.
Since EPD standardisation is still evolving, these inconsistencies are common and can limit the reliability of cross-manufacturer comparisons. As the EPD framework and standards continue to develop, greater consistency and comparability of data are expected. Until then, EPDs should be interpreted carefully within their specific context, rather than used as standalone ranking tools or for direct product comparisons across manufacturers.
