This article describes how the Allocation % feature works, and some use cases for it.
By default, the allocation is set to 100%, which means that 100% of the input that you have made in this row will be allocated to your results. In this example 0,43t CO2e.
If you change this value to, for example, 50%, only half of the emissions associated with this input will be allocated to your results.
The quantity will not change, however, the emissions will be multiplied by 50%. As seen below, the quantity remains as 500kg, but our emissions are reduced to 0,21t CO2e.
There may be many reasons to use this feature, some of which are described below:
Example 1. Allocate raw material inputs to different suppliers
For example, if you have two different suppliers of the same raw material, rather than change the input quantity and calculate a weighted average transportation distance (or if the transport methods are different), you can assign an allocation percentage depending on the share coming from each supplier.
In the below example, Supplier A is 250km away and we get 70% of our cement from there. Supplier B is 480km away and we received 30% of our cement from there.
Example 2. Co-product allocation
If during the production process, one of the raw materials leave this product system for use in a co-product, you can use the allocation feature to only assign the amount of the raw material that is used in the main product's process.
For example, you have 20kg of wood entering your system as raw material. Due to cutting of the wood to size, you have 2kg that is "waste". These off-cuts aren't sent to waste but instead used as raw material in the manufacture of a co-product. In line with co-product allocation rules, the emissions associated with this 2kg of wood can be allocated to the co-product system.
As such, you can apply 90% allocation of the input to this main product system.
Example 3. Average LCA
If you have multiple designs for multiple products and want to create an average LCA, the allocation feature can be used to split the share of inputs based on their production volume.
For example, we have individual LCAs for Products A, B and C, which make up 50%, 30%, and 20% of yearly production volume respectively. In order to create a single average LCA for all three products, we first copy all of the inputs for each design into one average design. Next we allocate 50% to Product A's inputs, 30% to Product B's, and 20% to Product C's.
This will give us a weighted average based on production volume for the three products.