For many small and medium-sized enterprises (SMEs), carbon accounting can feel intimidating. You know sustainability is becoming essential for winning tenders, maintaining supply chain relationships, and meeting regulatory expectations. Frameworks such as EcoVadis, CSRD, and the NHS Evergreen Sustainable Supplier Assessment now place increasing emphasis on emissions measurement and transparency.

But what if your business has no dedicated sustainability manager, no ESG analyst, and no in-house carbon knowledge?

The good news is that SMEs can still build a credible carbon accounting process without hiring a full-time expert. This guide outlines practical steps to get started quickly, affordably, and confidently.

Start With the Data You Already Have

Carbon accounting begins with gathering basic operational data. Most SMEs already hold much of what they need, including:

• Electricity and gas bills
• Fuel purchase records
• Travel expense reports
• Procurement spend data
• Waste management invoices

The UK Government provides a useful introductory guide for measuring and reporting environmental impacts:

https://www.gov.uk/guidance/measuring-and-reporting-environmental-impacts-guidance-for-businesses

And if you need a simple framework for assembling this data into a baseline, see Emerald Power’s internal guide:

Creating Your First Sustainability Report.

Focus on the Most Material Emission Sources for SMEs

SMEs do not need to measure every emission category at the start. Most emissions typically come from a few major areas:

Purchased Goods and Services

This usually represents the largest portion of Scope 3 emissions. When supplier-specific emissions data is unavailable, SMEs can use spend-based calculations, which estimate emissions using how much money was spent and on what types of goods.

The GHG Protocol provides detailed guidance on spend-based methods:

https://ghgprotocol.org/scope-3-technical-calculation-guidance

For a deeper dive into Scope 3 categories relevant to SMEs, see:

A Practical Guide – Calculating Your Scope 3 Emissions.

Business Travel

Travel records are often straightforward to gather through expenses. Airline, rail, and mileage data can be used to calculate emissions with government conversion factors.

Employee Commuting

A short staff survey can help identify commuting modes and distances. Even rough estimates provide a reasonable starting point.

Waste

Your waste management provider can supply data on waste types, weights, or collection frequencies.

Use Simple Tools Before Investing in Complex Platforms

SMEs do not need an enterprise-grade carbon accounting system to get started. Accessible and reliable resources include:

UK DEFRA emissions factors:

https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting

GHG Protocol calculation guidance:

https://ghgprotocol.org/

As SMEs grow or begin reporting to investors or supply chains, tools like Emerald Power can streamline the process by automating data collection and providing consistent emissions reporting across suppliers and portfolio companies.

Establish a Baseline and Build Your First Carbon Footprint

A carbon baseline is a fixed starting point against which future progress is measured. It should be based on a full 12 months of data whenever possible and include clear documentation of:

• What data was included
• The methods used
• Any assumptions or estimates

Your baseline does not need to be perfect. It simply needs to be transparent and repeatable.

For a structured approach to building your first sustainability report, see:

A Practical Guide: Creating Your First Sustainability Report.

Create a Simple and Actionable Carbon Reduction Plan

After calculating your emissions, the next step is identifying credible actions to reduce them. These do not need to be complicated. Common SME actions include:

• Switching to renewable electricity
• Reducing business travel or shifting to virtual meetings
• Asking top suppliers for emissions information
• Increasing recycling and improving waste segregation
• Implementing energy-efficient lighting or equipment

If your long-term goal is to align with global climate science, you can explore the Science Based Targets initiative (SBTi):

https://sciencebasedtargets.org/

Emerald Power also provides an internal guide on this topic:

How to Set Science Based Targets.

Seek External Support When Necessary

SMEs rarely need an in-house sustainability team. Instead, they can rely on external expertise including:

• Carbon accounting consultants
• Industry associations
• Local enterprise offices offering sustainability grants
• Software solutions that automate data collection

If your customers require reporting for EcoVadis or NHS Evergreen, or if you are preparing for new CSRD-aligned disclosures, external support can accelerate compliance and reduce internal workload.

See Emerald Power’s related guide:

How to Improve Your EcoVadis Score.

Start Small, Improve Over Time

Carbon accounting is an iterative process. SMEs should focus on getting started with what they can measure today and improving data quality year after year. Each cycle becomes easier, more accurate, and more aligned with customer and regulatory expectations.

FAQ

What is the easiest way for SMEs to begin carbon accounting?

Start by gathering existing operational data such as utility bills, travel records, fuel receipts, and procurement spend. This provides the foundation for your first carbon footprint.

Do SMEs need specialised software?

Not at the beginning. Free resources like DEFRA emissions factors and GHG Protocol guidance are enough to build an initial baseline. Software becomes valuable as reporting complexity increases.

What if I don’t have perfect data?

Carbon accounting does not require perfect data at the start. Transparent assumptions and reasonable estimates are acceptable when clearly documented.

What emissions categories should SMEs prioritise?

Purchased goods and services, business travel, employee commuting, and waste are typically the most material categories for SMEs.

Do SMEs need to measure Scope 3 emissions?

Increasingly yes, especially if supplying to large organisations or public-sector bodies. Many frameworks, including EcoVadis and the NHS Evergreen Assessment, expect Scope 3 reporting.