You’re ready to measure emissions - but the first steps can feel confusing: scopes, boundaries, emission factors, and a dozen different reporting acronyms. The good news is that you don’t need a perfect system on day one. You need a repeatable process you can improve each reporting cycle.

Most organisations end up aligning to the same core approach: build a greenhouse gas (GHG) inventory in line with the GHG Protocol Corporate Standard, then reuse that inventory for customers, investors, lenders, and reporting frameworks. [1]

In this guide, you’ll learn how to start in a way that is:

• Practical for a busy sustainability manager
• Credible enough for procurement and stakeholder questions
• Structured enough to scale into formal reporting later (for example, IFRS S2-aligned disclosures that reference GHG Protocol for measurement) [2]

Define what you're measuring and why

Before you touch a spreadsheet, write down your “why” in one sentence. This single line will shape what data you collect first and how much detail you need.

Common reasons include:

• Customer and supply chain requests (especially if you sell to larger firms)
• Tender requirements (public sector and enterprise procurement increasingly ask for emissions evidence)
• Financing (banks and investors want decision-useful information)
• Internal decision-making (energy cost reduction, travel policies, supplier strategy)

Even in the EU, where sustainability reporting rules have been actively simplified and narrowed toward the largest entities, smaller companies still experience the “trickle-down” effect through value chains and supplier questionnaires.[3]

Choose your standards baseline

To keep your emissions data usable across frameworks, it helps to choose a “home standard” for measurement:

• GHG Protocol Corporate Standard: the widely used corporate inventory approach for Scope 1 and Scope 2 (and often Scope 3). [4]
• ISO 14064-1: specifies principles and requirements for quantification and reporting at the organisation level; also supports verification-ready inventory management. [5]
• ‍Scope 3 Standard: structures value chain emissions into 15 categories and provides boundary-setting and reporting guidance. [6]

Practical tip: if you build your inventory using these standards, you’re usually well positioned to reuse it for other disclosure requests (for example, climate disclosure expectations that reference GHG Protocol for emissions measurement). [7]

Set your organisational boundary

Your organisational boundary defines which entities and operations are “in” your inventory (for example, subsidiaries, sites, joint ventures). The GHG Protocol approach includes different consolidation options (such as control-based and equity-share approaches), and consistency over time matters for credible year-on-year tracking. [8]

What to document (even if you start simple):

• The list of legal entities and sites included.
• How you treat leased assets and joint ventures (state the rule you chose)
• What is excluded, and why (temporary exclusions should have a plan)

Set your operational boundary

Now you define which emission sources you're counting and where they sit.

Data sources in carbon accounting are divided into three "Scopes". The easiest way to remember them is using the three "B's":

• Scope 1: Anything you BURN in fossil fuels
• Scope 2: Any electricity you BUY from the grid
• Scope 3: Anything BEYOND Scopes 1 and 2

See? It doesn't have to be complicated. Let's explore each scope in more detail.

Scope 1: Direct Emissions

Scope 1 emissions are direct emissions from sources owned or controlled by your business. These emissions come from activities directly under your organisation's control, such as fuel combustion in company vehicles, heating systems, generators and any chemical processes you operate.

Examples include natural gas burned in boilers, diesel used in company lorries, petrol for company cars and any other fuels you burn directly in owned or controlled equipment. If your organisation operates a fleet of vehicles or has on-site fuel combustion for heating or power generation, you'll have Scope 1 emissions to account for.

Scope 2: Indirect Emissions from Purchased Energy

Scope 2 emissions are indirect emissions from the generation of purchased electricity, heat, steam or cooling that you consume. Whilst you don't directly create these emissions, they result from your energy consumption. [9]

When you purchase electricity from the grid, emissions occur at the power station generating that electricity. Similarly, if you purchase district heating or cooling, emissions occur where that thermal energy is generated. Even though these emissions happen elsewhere, they're attributed to your organisation because they result from your energy consumption.

Scope 3: All Other Indirect Emissions

Scope 3 emissions are all other indirect emissions that occur in your value chain. This is typically the largest and most complex scope, covering both upstream emissions (in your supply chain) and downstream emissions (from your products or services). [10]

Scope 3 includes business travel in vehicles you don't own, employee commuting, purchased goods and services, waste disposal, transportation and distribution by third parties, use of sold products and much more. Whilst Scope 3 can seem overwhelming, you can start with the categories most relevant to your business and expand over time.

A quick memory device still helps - Burn, Buy, Beyond - but your inventory becomes credible when you connect those “B’s” to documented boundaries and sources.

Pick a baseline year and reporting cadence

A baseline year is the reference point you'll use to track progress.

Choose:

• A recent year with the best available data coverage
• A year you can reproduce from retained evidence (utility bills, fuel receipts, travel reports)

Plan to refresh at least annually. If your organisation changes significantly (acquisitions, divestments, major outsourcing or insourcing), you may need to reassess comparability and document what changed. The GHG Protocol emphasises credible reporting principles (including consistency and transparency) to support decision-useful results. [11]

Build your emissions source map

Carbon accounting succeeds or fails based on one thing: whether you can consistently get the right data, from the right owners, with an evidence trail. The fastest way to uncover where emissions sources exist and who owns the data is a short cross-functional mapping workshop. This approach supports Scope 3 screening and prioritisation (recommended in GHG Protocol Scope 3 guidance) and sets you up for clearer boundary and methodology disclosure expected in investor-grade frameworks (for example, IFRS S2’s emissions disclosure requirements and measurement expectations)

Start by listing all the activities in your business that might generate emissions, then organise them into the appropriate scope.

Don't worry about being perfect at first - carbon accounting is an iterative process. You'll refine your approach as you learn more about your emissions profile and become more familiar with the data available within your organisation.

Scope 1 starter list

• Natural gas or other fuels for heating/process heat
• On-site generators
• Company-owned vehicles or machinery.
• Refrigerants/top-ups from HVAC maintenance

Scope 2 starter list

• Electricity for sites (pull from utility bills or landlord statements)
• Purchased heat/steam/cooling if applicable

Scope 3 starter list

• Scope 3 is structured into 15 categories
• Don't try to do all 15 at once!
• Guidance exists to help calculate them, including different methods depending on data maturity [12]

A practical prioritisation could be:

1. Screen by spend and activity (what you buy, what you ship, where you travel)
2. Identify top categories likely to dominate (often purchased goods, transport, business travel, employee commuting, waste, use of sold products - depending on your sector)
3. Start with high - confidence data you can access quickly, then expand.

Assign data owners and create a “data request” rhythm

Carbon accounting succeeds when it’s a business process, not a once-a-year scramble.

Create a one-page data owner list: 

• Facilities/Operations: utilities, fuels, refrigerants
• Fleet/Travel: fuel cards, mileage, travel provider exports.
• Procurement/Finance: spend by supplier/category, freight invoices.
• HR: headcount, commuting survey inputs (if used)
• IT: cloud usage metrics (if relevant to your Scope 3 strategy)

Minimum viable cadence:

• Monthly capture for utilities and fuels (reduces year-end gaps)
• Quarterly capture for business travel and freight
• Annual refresh for procurement spend mapping and supplier engagement.

Decide where your emission factors will come from

An emission factor turns activity into emissions (kWh → kg CO2e). Official, regularly updated factor sets are preferable. For example:

• UK Government conversion factors are updated and explicitly intended for organisational GHG reporting (and are commonly used internationally as a reputable factor source). [13]
• The US EPA provides an emission factors hub designed for organisational greenhouse gas reporting. [14]

Also document which Global Warming Potential (GWP) values you use to convert gases into CO2e. GHG Protocol provides a ready reference updated with IPCC AR6 values and explains why AR6 is recommended (while acknowledging legacy AR4/AR5 usage in some schemes). [15]

Make it audit-ready from day one

Even if you’re not getting formal assurance this year, building an evidence trail now saves time later.

The GHG Protocol’s reporting principles emphasise credible, well-documented results, especially transparency and accuracy -supported by an audit trail. [16]

What“ audit-ready” looks like in practice

• Keep source files (bills, invoices, exports) in a structured folder.
• Log assumptions (missing months, estimation methods, unit conversions)
• Record decisions (boundary choices, exclusions, factors used)
• Version-control your workbook or platform outputs

Choose your tool: spreadsheet vs platform

A spreadsheet can work for a first-year baseline if:

• You have a small number of sites and simple operations.
• You can keep clean documentation and controls.

A platform becomes valuable when you need:

• Multi-site consolidation and repeatable workflows
• Supplier engagement (Scope 3 data requests)
• Dashboards, targets, and reporting outputs for multiple stakeholders
• Clean audit trails and permissions suitable for governance teams

If you want a faster path from “first baseline” to“ repeatable monthly process,” book a 15 minute demo of GreenFeet and see how to integrate emissions data with governance workflows.

Quick-start checklist

If you only have a few hours this week, do these in order:

• Write your “why” and your reporting audience.
• Choose organisational boundary rules and document them.
• List Scope 1 and Scope 2 sources by site.
• Pick your emission factor set and GWP version.
• Select 2–4 Scope 3 categories to start(screening approach)
• Assign data owners and cadence.
• Create an evidence folder and assumptions log.

Next in the series: Once you’ve got activity data, the next step is turning it into a baseline footprint using emission factors and clear calculation methods.