For most companies, the emissions that matter most are the ones they do not directly control. Scope 3 — the emissions across a company's value chain — typically accounts for 70–90% of the total footprint, and it is exactly where measurement is hardest because the data sits with suppliers and customers rather than on your own meters. This sits within our GHG accounting work and, at product level, our product carbon footprint service.
Scope 1, 2 and 3 in one line each
Scope 1 is direct emissions from sources you own or control (fuel, processes, fleet). Scope 2 is indirect emissions from the energy you purchase (electricity, steam, heating, cooling). Scope 3 is everything else in your value chain — both upstream and downstream — and it is governed by the GHG Protocol Corporate Value Chain (Scope 3) Standard.
The 15 categories
Scope 3 is divided into 15 categories — eight upstream and seven downstream. Upstream covers purchased goods and services, capital goods, fuel- and energy-related activities, transportation, waste, business travel, employee commuting and leased assets. Downstream covers transportation and distribution, processing and use of sold products, end-of-life treatment, leased assets, franchises and investments. Not all 15 are relevant to every company — but all 15 must be screened.
Why it is hard
Scope 3 data lives outside your organisation. Suppliers may not measure their emissions; customers' use of your products is outside your control; and the further down the value chain you look, the thinner the data gets. The honest answer is that Scope 3 is an estimate that improves over time, not a precise meter reading on day one.
The measurement methods — an accuracy ladder
- Spend-based: multiply money spent by an emission factor per unit of spend. Fast, complete, low accuracy — good for a first screen.
- Average-data: use physical activity data (kg, km, kWh) and average emission factors. More accurate than spend-based.
- Supplier-specific (activity-based): use primary data from your actual suppliers. Most accurate, most effort — reserve it for material categories.
Where to start
Screen all 15 categories quickly, usually with spend-based data, to find where emissions concentrate. For most companies that is purchased goods and services, and — for product makers — the use phase of sold products. Then deepen data quality only on those material categories. Trying to perfect all 15 at once is the most common way to stall a Scope 3 programme.
Why it matters now
Scope 3 is no longer optional. It is required under most disclosure standards (CSRD, IFRS S2), it is central to credible SBTi targets, and it increasingly appears on customer scorecards. The same value-chain data also underpins product carbon footprints and CBAM. Built once, properly, it serves all of them.
Sources & further reading
This article is general information, not legal, financial or compliance advice. The regulations and standards referenced here evolve; verify the current position with the issuing body, or ask us. Published June 2026.