20 Lessons from 20 Years

On carbon accounting, credibility, and getting the number right.

By Peter Birkett, Founder, Instep

Twenty years ago, almost no one asked us for a carbon number.

Instep was founded in 2006, at a time when greenhouse gas accounting was a niche exercise for a small number of organizations. Today it's a board-level requirement and increasingly a regulatory one, from CBAM to IFRS S1/S2 to national disclosure mandates now landing across Asia-Pacific.

We've spent those twenty years building GHG inventories, running lifecycle assessments, and verifying emissions data under ISO 14064-3 for clients across global markets. Along the way, some things about the work have stayed constant, and some have changed completely. Here are twenty things we've learned.

1. In 2006, almost no one asked for a carbon number. Now almost everyone does. The shift from voluntary to expected and increasingly mandatory happened faster than most organizations planned for.

2. A good inventory is a data project first, a sustainability project second. The sustainability framing matters for buy-in. The rigour that makes a number defensible is pure data discipline.

3. The number only matters if it can survive scrutiny. A carbon figure that can't withstand an auditor's, investor's, or regulator's questions isn't an asset, but a liability waiting to surface.

4. Scope 3 was optional for a decade. It isn't anymore. Value chain emissions are now where most of the real exposure, and most of the real work, sits.

5. Verification isn't a formality. It's what makes a number usable. An unverified inventory is a draft. Independent verification is what turns it into something you can publish, report, or defend.

6. Standards evolve faster than most organizations can keep up. The GHG Protocol, ISO 14064, SBTi guidance-all have moved substantially in twenty years, and the pace is accelerating, not slowing.

7. The best clients ask harder questions than the auditors do. Organizations that interrogate their own numbers before anyone else does end up with the most resilient reporting.

8. A footprint without a baseline is just a number, not a story. Context like trend, target, comparison is what makes an emissions figure mean something to the person reading it.

9. Regulation moves in waves. CBAM, IFRS S1/S2, mandatory disclosure — get ahead of it. Each wave gives organizations a runway before enforcement. The ones who move early spend that runway on preparation, not scrambling.

10. Most emissions hide in categories no one thought to measure. Purchased goods, business travel, waste, financed emissions — the overlooked categories are often where the biggest surprises live.

11. Credibility takes twenty years to build. One bad number to lose. This is the single biggest reason we treat verification and methodology as non-negotiable, even under commercial pressure.

12. The hardest part of an inventory is rarely the calculation. It's the data. Emission factors and formulas are well established. Getting clean, complete activity data out of an organization is the real work.

13. Every sector eventually gets its own carbon standard. Aviation got CORSIA and the Airport Carbon Accreditation programme. Others are following. Sector-specific frameworks are the direction of travel.

14. Clients don't remember the methodology. They remember whether the number held up. Under scrutiny, from a regulator, an investor, a journalist, durability matters more than elegance.

15. The people who prepare your inventory shouldn't be the ones who verify it. Independence between preparation and verification isn't bureaucracy. It's what makes ISO 14064-3 verification mean something.

16. Small consultancies survive on precision, not scale. We've never competed on size. Two decades in, precision is still the differentiator that matters.

17. The first inventory is always the hardest. The tenth is routine. Institutional knowledge compounds. What takes months in year one takes weeks by year three.

18. Investors started asking the questions regulators used to ask alone. Capital markets have become one of the strongest drivers of disclosure quality, sometimes ahead of the regulation itself.

19. The fundamentals haven't changed: measure it right, or don't publish it. Twenty years of evolving standards, and this principle hasn't moved an inch.

20. The next twenty years will be about proof, not promises. Commitments and targets got the last two decades started. Verified, comparable, decision-useful data will define the next two.

Twenty years in, the fundamentals are still what they were on day one: measure it right, or don't publish it.

To mark the anniversary, we're offering 20% off GHG Inventory Programme for new enrolments completed before the end of 2026.

Here's to the next twenty! -Peter Birkett