Detailed, in-house materials science or research are not expected for this VCA documentation requirement. However, companies should be able to make a well-informed calculation of the carbon impact of important input (material, ingredient, etc) choices to ensure that they are choosing lower carbon inputs, not just inputs that are suspected to be lower carbon.
To conduct this estimate, you may look to the following information sources.
Emission factor from an approved library: this could be from the BEE or an external tool tool like Worldly's Higg MSI tool or PlanetFWD’s product calculator. You may be able to demonstrate the difference in emissions directly in the tool by entering the same input amount for both factors - without any additional math.
Custom LCA documentation: this could be conducted by the brand or the supplier. It should demonstrate carbon impact vs a conventional input. Asking a supplier for this information demonstrates demand for inputs with lower-carbon attributes, and puts the onus on the supplier to research and provide it, and then be accountable to reducing product carbon emissions over time.
Reference to a credible 3rd party LCA or peer-reviewed research: this could be from an internet search, like this or this, showing X% decrease in emissions between a conventional and preferred input. This would need to be accompanied by a short description of why you believe this research is a good proxy for your own materials or production - for example, the emissions impact is very different for rPC10 vs rPC30 vs rPC100, so we'd look for an explanation of which value you are using to estimate and why. ** Please be careful to ensure the measurement boundary in the LCA or research study is comparable to your own! **
With documentation about the difference in carbon emissions from one of those sources, it is then simple to estimate the impact across your company. The calculation would look something like this:
➡️ Projected emissions impact = (conventional input emission factor - preferred input emission factor) * (amount purchased in the emissions year)