How do you calculate supplier-associated emissions?

We follow the GHG Protocol methodology for calculating scope 3 emissions, in this case 'Purchased Goods and Services' and use the spend-based method which estimates emissions for goods and services by collecting data on the economic value of goods and services purchased and multiplying it by relevant secondary (e.g. industry average) emission factors (e.g. average emissions per monetary value of goods).

This is industry standard and provides a robust estimation of the emissions from each industry. The most accurate approach is to gather total emissions of each supplier, divided by total sales and multiplied by your total spend with that supplier. This exercise requires intensive consultation with each supplier, but we believe that initiatives like TCFD will drive further transparency into company emissions in the future.