Advisory Request on Emission Factor Methodology Change

General
1

Hello,

I would like to take advantage of this community to seek advice regarding a change in the emission factor methodology for Scope 3 Category 1 calculations.

I am currently working with a Spanish company that has been reporting Scope 3 Category 1 emissions since 2019. Since the beginning, the company has used the DEFRA spend-based emission factors.

However, DEFRA has not updated this database since 2022. To address this issue, the previous consultancy updated the factors manually by adjusting them according to the GBP-EUR exchange rate and inflation rates, for each year, in order to approximate more recent values.

This year, I suggested changing the database and using the Open CEDA dataset provided by Watershed instead. However, after conducting an impact analysis, the results showed an increase of more than 59% in Scope 3 Category 1 emissions.

As a consequence, the company may need to recalculate emissions for all previous reporting years to maintain consistency and comparability.

I would appreciate your thoughts on this situation and any advice on how you would approach this type of methodology change.

And how you would approach if company refuses the recalculation of the previous years.

Thank you in advance.

2

Hi Carla,

In case of a methodology change (which this would be), a recalculation of at least the base year is unavoidable. Recalculating all years between the base year and most recent year is, on the other hand, optional and only necessary if the company requires this for reporting/ tracking.

That being said: If the company is basing majority of their Inventory on spend-based figures, they are likely not as advanced/ have such high data requirements when it comes to their GHG Inventory. Therefore, a recalculation of all years may be a bit overkill.

I personally do use older spend-based EFs and apply an inflation-factor to adjust them to the respective year. However I only do so because the resulting emissions make <1% of our customers GHG Inventory. If the majority of the inventory relies on spend-based EFs, I would highly recommend using a database that is regularly updated/ more recent or (ideally) start switching to a volume-based approach (if applicable to this customer).