ISO 14064 Verification: The Ultimate Guide

If you’re getting asked for "verified" carbon numbers by customers or investors, ISO 14064 is likely the standard they have in mind. It gives organisations a consistent way to measure greenhouse gas emissions, explain what’s included, and have an independent expert check the work. For businesses, that means fewer credibility questions, smoother procurement, and a stronger base for targets and plans.

What is the ISO 14064 standard?

ISO 14064 sits within the wider ISO 14000 family of environmental standards and focuses specifically on greenhouse gases. Think of it as three parts that work together.

ISO 14064-1 is a blueprint for an organisation-wide greenhouse gas inventory. It sets expectations for boundaries, data collection across Scopes 1, 2, and 3, calculation methods, and transparent reporting.
ISO 14064-2 deals with quantifying and reporting results from specific reduction projects. Helpful when you want to show the impact of a defined initiative, though most businesses begin with the organisational inventory.
ISO 14064-3 explains how an independent verifier should assess what you’ve reported. That’s the assurance step that turns “we measured it” into “a qualified third party has checked it”.

The overall process is: start with 14064-1 to get the organisational footprint right, then use 14064-3 to verify it. ISO 14064-2 is helpful but less commonly used.

What's the difference between ISO 14064-1 and the GHG Protocol?

The GHG Protocol is the most widely used guidance framework for measuring and corporate greenhouse gas emissions, while ISO 14064-1 is an auditable standard written so an independent third party can formally check and certify whether a company’s greenhouse gas report follows its requirements. In practice, companies often use the GHG Protocol to calculate emissions and ISO 14064-1 to verify and report them. You can read a detailed breakdown in the table below:

Both the GHG Protocol and ISO 14064-1 divide emissions into direct and indirect categories, but they label and structure them differently.

The GHG Protocol uses Scope 1 (direct), Scope 2 (energy-related indirect), and Scope 3 (other indirect), with Scope 3 further broken into 15 detailed categories such as purchased goods, transport, and waste.
ISO 14064-1 uses Direct, Energy-indirect, and Other indirect categories - conceptually the same, but it doesn’t prescribe fixed categories. Instead, it requires you to define what’s included, justify your approach, and report transparently.

So when it comes to measurement and reporting, the real difference is that ISO 14064-1 is less prescriptive: it sets out requirements for consistency, documentation, and verification but not the exact calculation methods.
The GHG Protocol is more detailed and stricter in practice, providing specific guidance on how to categorise, calculate, and report emissions - especially for Scope 3.

Should I use ISO 14064-1 or the GHG Protocol?

Use the GHG Protocol to calculate and manage your emissions - it’s the global baseline and required by programs like CDP and SBTi. Then apply ISO 14064-1 if you need a formally verified, auditable report. They’re fully compatible, so you can build your inventory with the GHG Protocol and have it verified against ISO 14064-1 without redoing the work. The extra effort will be in providing ISO-style documentation (e.g., base year & recalculation policy, uncertainty/data quality, intended use, org/operational boundaries) as we explain later on in this article.

In short: use the GHG Protocol for how to measure, and ISO 14064-1 for how to structure and verify your reporting.

Why get verified under ISO 14064?

Once, you've measured your business' GHG inventory - either independently or with support from experts like Seedling - ISO 14064 verification is an optional next step that provides a third-party opinion on accuracy and documentation for stakeholders who need extra assurance.

ISO 14064 verification helps to build trust in your data, and may be required by clients or particular accreditation schemes. However, given verification also entails additional cost (verifier fees), many businesses only choose to engage with verification if required.

Top tip: if you're asked for verified carbon data, double check what your client/certification scheme actually requires. They may simply mean independent assurance - such as from a carbon accountant (like Seedling) - that your footprint has been calculated in line with the GHG Protocol.

The process: how to verify under ISO 14064

Step one: compile your emissions inventory in line with ISO 14064-1

First, decide your organisational and operational boundaries - the "thing" that you are completing a footprint for, and which elements within that footprint are under your direct control vs. will be classed as indirect emissions. Be clear on which legal entities and sites you’re covering, how you define control, and which period you’re reporting for.

Then, collect data across all three scopes to measure your emissions. Use the GHG Protocol as your methodological foundation for defining and calculating Scopes 1, 2, and 3, and apply the ISO 14064-1 structure to ensure your inventory meets the requirements for future verification. Aim for activity-based inputs wherever possible because they reflect reality and make year-on-year change meaningful. That means kilowatt hours rather than the value of an electricity bill, litres of fuel rather than spend at the pump, kilometres travelled rather than ticket price, and kilograms or units of material rather than purchase order value. Apply recognised emissions factors consistently, document your sources and assumptions, and keep a record of any estimates you needed to make, plus plans to improve them next cycle.

You can build the inventory in-house, hire a consultant, or use a carbon management platform designed for businesses. If you do bring in external help to prepare the footprint, that same organisation should not verify it. Independence matters. The verifier must be able to challenge your assumptions without conflict.

Expect an iterative first year. Most businesses see a big accuracy jump in year two once data gaps are known and processes are bedded in. Treat it like you would quality management: set up sensible data processes, keep evidence tidy, and review methods annually.

Step two: seek verification under ISO 14064-3

ISO itself can't help with verification - they just provide the standard to follow. Instead, you contract an independent verification body that works to 14064-3. The most credible route is to pick a provider accredited by a national body, such as UKAS in the UK. In the EU, look for verifiers accredited by national agencies under Regulation 765/2008. In the US, the ANSI National Accreditation Board is the reference point. This route usually costs more, but carries greater weight with customers and scorecards because the verifier’s own processes are regulated and audited.

You’ll agree an assurance level. Limited assurance is a lighter review that asks whether anything has come to the verifier’s attention to suggest a material misstatement. Reasonable assurance goes deeper, with more testing and evidence, and results in a stronger conclusion. If stakeholders don’t specify, many businesses start with limited to prove the process, then step up to reasonable as expectations grow.

What the engagement looks like in practice:

Scoping: you and the verifier agree the boundary, period, assurance level, and timetable.
Document review: the verifier examines your methods, emission factors, data sources, and controls.
Sampling and testing: they select a cross-section of figures across Scopes 1, 2, and 3 and trace them to underlying evidence. For energy, that could mean meter reads or supplier statements. For travel, booking records or mileage logs. For purchased goods, supplier data or weight-based calculations.
Site visits or remote checks: many business verifications are remote if records are complete. Some engagements include visits to confirm meters, logs, or other activity data.
Queries and corrections: expect questions. You’ll clarify assumptions, fix errors, and strengthen evidence where needed.
Verification statement: you receive a formal statement that sets out the scope, standards used, assurance level, and any qualifications.

The outcome is binary on credibility: either you can show an independent statement alongside your footprint, or you can’t.

What it typically costs

There are two cost lines to think about: preparing the inventory and verifying it. For the first:

Doing everything in-house has the lowest cash cost but demands time and capability. You’ll need someone comfortable with data collection, emissions factors, and documentation.
Working with a consultant usually improves data quality, particularly across Scope 3, but can be expensive.
The "best of both" approach is often to work with a software platform like Seedling - you get one-to-one expert guidance from a dedicated account manager, but you'll use software to make the process more efficient and affordable.

For 14064-3 verification, a UKAS-accredited engagement might start around £5k for a simple, single-entity inventory at limited assurance. Costs rise into five figures for reasonable assurance, multi-site operations, complex Scope 3 categories, or group structures. Non-accredited verification is typically cheaper, but carries less weight with some buyers and schemes.

How Seedling can help

Seedling is designed to make ISO-aligned carbon accounting manageable for small and mid-sized teams. On the platform, you collect the right data across Scopes 1, 2, and 3, apply recognised factors consistently, and produce a transparent inventory that stands up to scrutiny. You also get one-to-one expert support to choose the right methods, plug data gaps, and improve accuracy year on year. You're guided through the whole process one-to-one, saving you time and giving you confidence in your results.

When you’re ready to verify, we introduce trusted UKAS-accredited partners and help you prep so the process is efficient. That means agreeing scope and materiality early, organising evidence so sampling runs smoothly, and sense-checking your narrative before the auditor sees it. You end up with the two assets that matter most: a credible inventory and an independent verification statement you can reuse across bids, investor packs, CDP, and B Corp submissions.