An audit-ready Scope 3 emission factor is built from the economic data of the country where you spend, updated every year, detailed enough to match what you buy, backed by a peer-reviewed method, and traceable to a published source. FootprintLab's Australian factors meet all five tests, and Unravel Carbon customers can now use them directly in the platform.
Key takeaways
- Two companies buying the same goods can report different Scope 3 emissions because they used different emission factors, and auditors question that choice.
- FootprintLab's factors are built by IELab, a research programme of the University of Sydney and UNSW, and are the benchmark spend-based factors in Australia.
- Unravel Carbon records the database and publisher behind every calculation, so the source trail exists before assurance starts.
- Under AASB S2, Scope 3 disclosure starts in a company's second reporting year.
Why does the choice of emission factor change your Scope 3 result?
Most Scope 3 figures are calculated from spend. An emission factor converts each dollar in the purchase ledger into tonnes of CO2e, so two companies can buy the same steel from the same supplier and report different emissions for it. The GHG Protocol ranks the spend-based method as the least specific way to calculate Scope 3, which leaves the factor as the part of the calculation a company controls most. Under AASB S2, that choice has to hold up in front of an assurance provider and behind a directors' declaration.
What makes an emission factor audit-ready?
The GHG Protocol's Scope 3 Standard judges secondary data on how well it represents the technology, time and geography of the activity, and on its completeness and reliability. For a spend-based factor, that comes down to five questions an assurance provider is likely to ask.
Geographic fit matters most. Spend-based factors come from input-output tables that describe how one country's industries buy from each other, so a factor built from UK or US tables describes UK or US supply chains, and applying it to Australian spend gives the auditor something to question.
Where does FootprintLab's data come from?
FootprintLab holds the exclusive commercial licence to data from IELab, the Industrial Ecology Virtual Laboratory, a joint research programme of the University of Sydney and UNSW. IELab builds its factors from national statistics and international sources such as the IEA, OECD and UN Comtrade, and has published its methodology in peer-reviewed journals. FootprintLab was co-founded by Janet Salem, who led sustainability programmes at the United Nations, and Dr Tim Baynes, a former senior scientist at CSIRO.
According to FootprintLab, the Australian Government's Climate Active scheme sources its Scope 3 spend-based factors directly from IELab, and state and federal government bodies use the same data.
What do Unravel Carbon customers get?
Customers apply FootprintLab's factors to their purchasing data inside the platform, without licensing or loading the data themselves. That includes:
- Factors for 344 Australian product and industry classes under IELab's ISAPC classification, the one used to supply Climate Active
- Factors for 500 sectors under ANZSIC, the industry classification used by the Australian Bureau of Statistics
- The database and publisher recorded against each calculation and visible to the customer, ready for when an assurance provider asks
Why does this matter now?
AASB S2 gives one year of relief on Scope 3, so disclosure starts in the second reporting period. Group 1 entities began with reporting periods starting on or after 1 January 2025, which puts many of them in their first Scope 3 year now, and Group 2 entities began on 1 July 2026. Assurance is being phased in, reaching reasonable assurance of climate disclosures from 1 July 2030.
Climate Active is also closing. On 24 July 2026 the Australian Government announced it will end certification of voluntary climate claims, with 30 June 2027 proposed as the end date. The Scope 3 spend-based factors the scheme used came from IELab, and FootprintLab continues to publish them each year.
Frequently asked questions
What is a spend-based emission factor? A spend-based emission factor converts money spent in a sector, for example $1 of freight services, into kilograms of CO2e. It covers the emissions of that sector and its own supply chain, and it is used for Scope 3 when supplier-specific or activity data is not available.
Does AASB S2 require a specific emission factor database? No. AASB S2 requires emissions to be measured in line with the GHG Protocol unless another method is required by law, and it does not name a database. Reporters need a documented choice of factors that an assurance provider can trace back to its source.
When do Australian companies have to report Scope 3 under AASB S2? From their second reporting period. AASB S2 gives one year of relief on Scope 3, so a reporter discloses Scope 1 and 2 in its first year and adds Scope 3 in its second.
What happens to Climate Active emission factors when the program closes? The Scope 3 spend-based factors Climate Active used were supplied by IELab. FootprintLab continues to update and publish them annually, and Unravel Carbon customers can apply them to their purchasing data in the platform.
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