A supply mix is a Production mix with the addition of the import of the specified product to the geographical area. This concept is essential in Life Cycle Assessment for accurately representing the total availability of a product within a defined geographical boundary.
Whilst the production mix represents only the production-volume-weighted average of suppliers producing a specific product within a geographical area, the supply mix provides a more complete picture by accounting for both domestic production and imported quantities. This distinction is particularly important when modelling product systems in LCA, as many geographical areas rely on a combination of locally produced goods and imported products to meet total demand.
The supply mix calculation combines the weighted contributions of all domestic producers with the weighted contributions of imports, creating a comprehensive representation of how a product is supplied to a market. This approach ensures that Life Cycle Inventory analysis accurately reflects the environmental burdens associated with both production activities within the geographical area and the upstream impacts embedded in imported products.
In practice, determining the appropriate geographical boundaries for a supply mix requires careful consideration of market structures, trade flows and the goal and scope of the LCA study. For globalised products with significant international trade, the supply mix may differ substantially from the production mix, as imports can represent a large proportion of total supply. Conversely, for products with limited trade or strong regional production, the supply mix may closely approximate the production mix.
Understanding the difference between production mix and supply mix is crucial for consequential LCA modelling, where the geographical scope of affected markets and the role of international trade can significantly influence which activities are expected to change in response to changes in demand.
