Scope 3 Emission Factors
Where to find them and how to choose the right ones.
Emission Factor Selection
Selecting the correct emissions factors is an important part in emissions inventory and carbon reporting to ensure accuracy and reproducibility of the findings. Previously, we shared Our Perspective on Emission Factor Selection for voluntary carbon accounting where we delve deeper into the topic. However, particularly for Scope 3, or value chain emissions, finding suitable emission factors can be an issue.
There is a growing number of organisations that are giving self-reporting a go. So this post is aimed at small and medium businesses operating in Aotearoa New Zealand that are not in a certification programme (such as with Ekos or Toitū Envirocare), are not using a software measurement tool that provides credible factors, and do not engage a consultant to source factors for them.
Resources for Emission Selection
The first point of call for finding and selecting New Zealand-specific scope 3 factors should be the Ministry for the Environment | Manatū mō te Taiao's voluntary reporting guidance document, which can be found here.
Further resources for scope 3 emission factors are:
The Consumption Emissions Modelling Report (2023) for Auckland Council, which is essentially a guide to spend-based factors.
And thinkstep-anz have released Emission Factors for New Zealand: Greenhouse Gas Emissions Intensities for Commodities and Industries - a report on scope 3 corporate carbon footprinting.
If you cannot find the factor you require in the references above, need a factor for activities overseas, and/or have an unusual requirement then consider:
IPCC Emissions Factor Database - a library of emission factors and other parameters with background documentation or technical references.
Life Cycle Databases - a list of third-party databases compiled by the Greenhouse Gas Protocol.
Environmental Product Declarations - a registry of Environmental Product Declarations (EPDs) and Climate Declarations for businesses in Australia and New Zealand.
Carbon product footprint study or life cycle assessment for a product or service. The study will have been completed in accordance with ISO 14067 or ISO 14040 series and will have undergone external assurance or a critical review. Product suppliers (e.g. courier bags) can provide the outcome of these studies.
How to select the correct emission factor
Often you will find various or diverging emissions factors for the same activity, depending on where you look or how you assess the activity or purchased good or service. In this case, our advice is to choose the most conservative factor as that is in line with the principles of the GHG Protocol and ISO 14064-1.
Feel free to contact us at info@mchugh-shaw.co.nz to discuss your assurance requirements or request our free GHG Protocol Scope vs ISO Category Comparison Table. We have over 15 years of experience and complete ISO 14064-1, GHG Protocol, ISO 14067, Airport Carbon Accreditation, Eco Choice Aotearoa, Product Stewardship and Aotearoa New Zealand Climate Standard assurance.
Last Updated August 2025