How to Report Carbon Data to Clients: A Practical Guide

A clear, step-by-step guide to carbon reporting

If you’re reading this article, chances are you’ve started receiving requests from clients asking for your carbon data. Whether it’s a tender requirement or part of a supply chain questionnaire, these requests are only going to grow.

For businesses that don't have a team of in-house sustainability experts, the first reaction is worry: What do we actually need to provide? How much work is this going to take? Will it expose us if our numbers aren’t perfect?

The good news is that carbon reporting doesn’t need to be a time sink. With the right approach, you can provide your clients with credible data – and even use it as a chance to stand out.

Why businesses are being asked for carbon data by clients

If your clients are asking you for emissions data, it's because they themselves are under pressure to measure and report on carbon. This could be because of:

Regulation – Larger businesses are under new requirements (from SECR to ISSB and CSRD) and need supplier data to complete their own Scope 3 reports.
Procurement frameworks – PPN 006 (06/21) in the UK makes carbon reporting a requirement for many public sector contracts.
Funding requirements – Carbon emissions and a Net Zero strategy are increasing a criteria for investment, or a route to more affordable funding (for instance - through sustainability linked loans (SLLs)).

In short: if your clients are asking, it’s because they need your data to meet their own compliance needs.

What does a carbon data request look like?

Carbon data request can come in many forms. You might be asked to submit emissions data through a recognised third-party assessment, such as:

EcoVadis - a supply chain sustainability assessment widely used by large organisations. This questionnaire goes beyond carbon, but emissions are a key aspect.
The Carbon Disclosure Project (CDP) - a widely used portal for environmental submissions.

You may also be asked to submit carbon data through a portal managed by your supplier, or simply via email.

Carbon reporting frameworks: the GHG Protocol and the SBTi explained

Let's take a look at the two real-life examples of carbon data requests, shown in the image below:

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You'll spot two pieces of terminology which are commonly used to structure carbon reporting: the 'Scopes' and 'Net Zero'. We'll explore each of these in turn, so you can understand what your clients expect:

The GHG Protocol

‍The Greenhouse Gas Protocol is the global standard for measuring emissions. It sets out a step-by-step process for calculating and talking about emissions that all businesses should follow.

When you receive a request for carbon data, it will likely ask you to follow the GHG Protocol in your approach. It divides your footprint into:

Scope 1: Direct emissions from fuel use (e.g. on-site, or company vehicles).
Scope 2: Indirect emissions from purchased energy (e.g. office electricity).
Scope 3: Wider supply chain emissions (e.g. purchased goods, shipping, employee commuting).

To get started with measuring emissions, read our Carbon Accounting Beginner's Guide.

Science Based Targets initiative (SBTi)‍

While the GHG Protocol is about measurement, the SBTi is about targets, specifically Net Zero targets. It provides the global standard for setting emissions reduction goals in line with climate science.

By following the SBTi's framework, you ensure that when you say “Net Zero,” you're committing to a pathway that matches the 1.5°C Paris Agreement trajectory. You can learn more about what this means in practice in our Net Zero guide.

Businesses are increasingly expected to set interim targets (by 2030) and long-term Net Zero commitments (by 2050).

The key takeaway: you'll likely be expected to follow the GHG Protocol and SBTi in your carbon reporting to ensure credibility.

What to include in your client carbon report

Most client requests boil down to a few essentials:

Your carbon footprint (Scopes 1, 2, and 3) in line with the GHG Protocol.
Your Net Zero targets, and plan to reduce emissions over time, not just a one-off number.‍
Assurance that the methodology is robust – not just a rough calculation.

What's the difference between third-party verification and assurance in carbon reporting

Large corporations often pay for full third-party verification of their carbon footprint, often by a UKAS accredited partner – essentially an audit by an external consultancy to check that both the measurement approach you take and the underlying business data that on which your calculation are based is accurate. This can cost tens of thousands of pounds, so typically isn't something that your clients will ask for.

Instead, what is often asked for is assurance: confirmation that your footprint has been measured in line with the GHG Protocol by a trusted platform and team of experts. This gives your clients confidence in your methodology, without the need for significant cost or time investment.

Note: confusingly, terms like verification and assurance, and the definition of third-party, are often used incorrectly and interchangeably. The best approach? Clarify expectations with your supplier. Ask what level of verification is required. Do they need full UKAS-accredited verification and data-checking, or - as it typically the case -assurance from a third party that your methodology aligns with the GHG Protocol.

Ultimately, what your client needs is confidence you haven't quickly fudged the numbers, but are providing accurate data they can rely on.

Do I need to submit my SBTi targets for approval

Another feature of client carbon reporting worth double-checking relates to your SBTi-aligned Net Zero target. It's possible to pay to have your Net Zero target approved by the SBTi.

However, many business don't require SBTi submission - they simply need you to set your Net Zero target within the SBTi's rules, and to evidence this. Double checking what's needed by your client could save you a fee.

Carbon reduction vs. offsetting: what clients expect

Another common question is: “Can’t we just offset?”

Offsetting has a role, but clients increasingly expect to see a credible reduction pathway first. Offsetting alone isn’t enough.

Reduction: Cutting emissions at source (switching to renewable energy, supplier engagement, efficiency measures).
Offsetting: Funding external projects to remove or avoid emissions.

Using the SBTi's framework will help you to find the right balance, prioritising real reductions before investing in high-integrity offsets. Still unsure - read our Carbon Reduction VS. Offsetting Guide for more detail.

Case Study - Reporting Carbon Data to Microsoft

Read how Janea Systems submitted carbon data to their client - Microsoft - easily and credibly, with help from Seedling.

Read how Seedling helped Janea Systems report carbon data to Microsoft

Ready to get started with carbon reporting? Seedling can help

Client carbon reporting can feel intimidating, but it doesn't need to be.

Whether you're overwhelmed as a sustainability team of one, tackling carbon reporting for the first time in an Ops, SHEQ, or marketing role, or looking to switch from DIY calcs and consultants to straightforward, streamlined, and credible carbon reporting, Seedling can help.

With our easy-to-use software plus support from your dedicated carbon expert, we'll help you to:

Measure an accurate, full-scope footprint, assured by Seedling to align with the GHG Protocol methodology
Set targets in line with the SBTi framework, with all the data you need for SBTi submission
Build a practical, data-backed plan to reduce emissions
Offset by investing in high-integrity projects that benefit both people and planet
Build client-ready reports, in just a few clicks

We already help 250+ businesses to track, reduce, and report emissions, including to blue chip clients such as Microsoft, KPMG, and UBS.

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👉 Ready to turn carbon reporting into an opportunity? Book a call with our team.

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