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If you’re part of a sustainability team, you already know that the road to net zero is rarely linear. It's a winding path with three core milestones: reducing your Scope 1, Scope 2 and Scope 3 emissions. Each scope represents a different type of carbon impact and each brings its own set of data challenges, reduction strategies and stakeholder conversations.
But beyond definitions and diagrams, you need something more practical - a route map that balances technical accuracy with commercial pragmatism. One that equips you to track, reduce and report emissions, while making a watertight business case internally.
This guide does just that. We draw from leading frameworks (GHG Protocol, CDP, SBTi, CSRD), regulatory context (UK SECR, EU taxonomy) and practical resources (DEFRA, Quantis, CDP) to help you navigate the complexities and take action with confidence.
What Are the Three Scopes of Emissions?
The Greenhouse Gas Protocol - the most widely used emissions accounting standard globally - defines carbon emissions across three scopes:
| Scope | Description | Example |
|---|---|---|
| Scope 1 | Direct GHG emissions from owned or controlled sources | Onsite fuel combustion, fleet vehicles, refrigerant leaks |
| Scope 2 | Indirect GHG emissions from purchased energy | Electricity, steam, heating, cooling |
| Scope 3 | Indirect GHG emissions in the value chain | Purchased goods, business travel, product use, waste, investments |
Scope 1 Emissions: Direct Emissions from Your Operations
Scope 1 emissions are direct emissions from sources your organisation owns or controls. These typically include:
- Stationary combustion (e.g. natural gas in boilers)
- Mobile combustion (e.g. petrol/diesel fleet vehicles)
- Fugitive emissions (e.g. refrigerant or fire suppressant leaks)
- Process emissions from industrial operations.
How to Measure
- Collect consumption data (e.g. litres of fuel, kWh of gas)
- Apply UK government DEFRA conversion factors
- Review refrigerant logs for leakage estimates.
Reduction Strategies
- Electrify fleet vehicles
- Switch to low-carbon heating (heat pumps, biofuels)
- Track and repair refrigerant systems
- Use smart controls and voltage optimisation.
Scope 2 Emissions: Indirect Emissions from Purchased Energy
Scope 2 covers indirect emissions from the generation of purchased electricity, heating or cooling. These occur offsite but are directly tied to your usage.
How to Measure
- Gather consumption data from electricity and utility bills
- Report using both location-based (average grid emissions) and market-based (supplier-specific) methods per the GHG Protocol
- Refer to the latest UK emissions factors from BEIS.
Reduction Strategies
- Switch to REGO or REC-backed green tariffs
- Sign corporate PPAs for renewable power
- Invest in on-site solar PV or battery storage
- Implement LED lighting and BMS systems.
Scope 3 Emissions: Indirect Value Chain Emissions
Scope 3 includes all other indirect emissions created across your company's value chain, both upstream (e.g. suppliers) and downstream (e.g. product use).
Even though they are indirect, Scope 3 emissions often account for the majority of a company’s total emissions, so they are essential to pay attention to.
The GHG Protocol identifies 15 categories of Scope 3 emissions in a value chain and all that are relevant to your company should be accounted for:
Upstream:- Purchased goods and services
- Capital goods
- Fuel- and Energy-Related Activities
- Upstream transportation and distribution
- Waste generated in operations
- Business travel
- Employee commuting
- Upstream leased assets
Downstream:
- Downstream transportation and distribution
- Processing of sold products
- Use of sold products
- End-of-Life treatment of sold products
- Downstream leased assets
- Franchises
- Investments.
Further information and descriptions of each GHG Protocol Scope 3 category can be found here.
Measuring and reducing scope 3 emissions is often challenging as it relies on influencing external partners and suppliers across your value chain to report and reduce their emissions. However, Scope 3 is where the biggest potential for decarbonisation lies.
How to Measure
Use one or more of the following:
- Spend-based: Estimating emissions based on procurement costs and industry emission factors
- Activity-based: More precise, using kWh, tonnes, or miles
- Supplier-specific: From CDP disclosures or life cycle assessments (LCAs)
- Hybrid: Combine data types and fill gaps strategically.
Reduction Strategies
- Collaborate with suppliers on joint emissions reduction targets
- Prioritise sustainable vendors and procurement
- Introduce circular product models and reuse schemes
- Launch employee EV salary sacrifice schemes and public transport incentives
- Educate customers on proper product disposal or recycling practices.
What About Scope 4?
As the climate crisis progresses, a new carbon accounting method has emerged; Scope 4.
Scope 4 or 'avoided emissions' refers to emissions that are prevented by your product or service. For example, a SaaS platform reducing the need for servers or travel and the associated carbon emissions.
While not yet officially recognised by the GHG Protocol, Scope 4 is increasingly relevant for EU CSRD and taxonomy-aligned companies aiming to quantify climate-positive impact.
Regulatory & Reporting Requirements
| Framework | Region | Requirement |
|---|---|---|
| CSRD | EU | Scope 1–3 mandatory, assurance required, phased from FY 2024 |
| SECR | UK | Scope 1 & 2 mandatory for large businesses |
| SBTi | Global | Scope 3 mandatory if >40% of total emissions |
| CDP | Global | Voluntary disclosure, widely used by investors |
GHG Protocol
The Greenhouse Gas Protocol is the globally recognised standard for carbon accounting. It provides the foundational structure for classifying and measuring Scope 1, 2 and 3 emissions and underpins most sustainability reporting frameworks and tools used today. For any organisation serious about decarbonisation, aligning with the GHG Protocol is essential.
SBTi (Science Based Targets initiative)
The SBTi helps organisations set carbon reduction targets that are aligned with global climate science, specifically, limiting global warming to 1.5°C above pre-industrial levels. If more than 40% of your emissions fall under Scope 3, SBTi requires you to include them in your targets. As net zero strategies come under greater scrutiny, SBTi validation is fast becoming a benchmark for credibility.
CSRD (Corporate Sustainability Reporting Directive)
Introduced by the EU, CSRD mandates robust sustainability disclosures for thousands of companies operating in Europe. It requires detailed reporting of Scope 1, 2 and 3 emissions, along with third-party assurance and alignment to the EU’s sustainability taxonomy. Phased implementation begins with large listed companies from FY 2024.
SECR (Streamlined Energy and Carbon Reporting)
A UK regulation that requires large businesses and LLPs to report on their energy use and carbon emissions. Scope 1 and 2 emissions reporting is mandatory, while Scope 3 remains voluntary but recommended. SECR is designed to bring consistency and transparency to corporate emissions data.
CDP (formerly Carbon Disclosure Project)
CDP operates a global disclosure system for investors, companies and cities to manage their environmental impacts. Submitting through CDP is voluntary, but widely regarded as a best practice and increasingly requested by stakeholders, from clients to shareholders.
Measuring and reducing emissions across all scopes is no small feat - but it’s foundational to any credible net zero strategy. And for sustainability professionals navigating the demands of internal stakeholders, auditors and regulators, the ability to back your plans with accurate data and a clear ROI narrative has never been more essential.
Start with what you can measure, readjust as you go and never lose sight of the bigger picture: reducing emissions means reducing risk, unlocking efficiencies and creating future-fit organisations.
If you'd like more practical guidance on building a commercially viable carbon strategy, speak to our experts.
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