Scope 1, 2, and 3 Emissions: A Complete Worked Example for a Small Business
The Company: Hartmann Technical Services Ltd
To make this concrete, we will walk through a complete Scope 1, 2, and 3 GHG calculation for a fictional company: Hartmann Technical Services Ltd, a 22-person engineering services firm based in Birmingham, UK. They have one office with a gas central heating system, one company diesel van, and employees who commute by car and occasionally fly to client sites.
This is a real-world profile matching thousands of UK and EU SMEs.
Step 1 — Scope 1: Direct Emissions
Scope 1 covers direct combustion at premises you control and vehicles you own or operate.
Natural gas (office heating): Hartmann's annual gas bill shows 42,000 kWh of consumption. - Convert kWh to m³: 42,000 ÷ 11.2 = 3,750 m³ - Apply DEFRA 2023 factor: 3,750 × 2.04 kgCO2e/m³ ÷ 1,000 = 7.65 tCO2e
Diesel van (one vehicle, 18,000 km/year): The van averages 9 km per litre. - Litres consumed: 18,000 ÷ 9 = 2,000 litres - Apply DEFRA 2023 factor: 2,000 × 2.68 kgCO2e/litre ÷ 1,000 = 5.36 tCO2e
Scope 1 total: 13.01 tCO2e
Step 2 — Scope 2: Purchased Electricity
Hartmann's office consumed 38,000 kWh of electricity during the year. They are on a standard (non-renewable) tariff.
Location-based (DEFRA 2023 UK grid): - 38,000 × 0.193 kgCO2e/kWh ÷ 1,000 = 7.33 tCO2e
Market-based: Same figure because no renewable tariff is held.
Scope 2 total: 7.33 tCO2e
Step 3 — Scope 3: Indirect Emissions
Category 3 — Well-to-Tank (WTT) — auto-calculated from Scope 1
WTT covers upstream extraction and processing of fuels burned in Scope 1.
- Natural gas WTT: 3,750 m³ × 0.376 kgCO2e/m³ ÷ 1,000 = 1.41 tCO2e
- Diesel WTT: 2,000 litres × 0.641 kgCO2e/litre ÷ 1,000 = 1.28 tCO2e
- Category 3 total: 2.69 tCO2e
Category 5 — Waste
Hartmann's waste contractor confirms they send approximately 3 tonnes to landfill and 1 tonne to recycling per year. - Landfill: 3,000 kg × 0.459 kgCO2e/kg ÷ 1,000 = 1.38 tCO2e - Recycling: 1,000 kg × 0.021 kgCO2e/kg ÷ 1,000 = 0.02 tCO2e - Category 5 total: 1.40 tCO2e
Category 6 — Business Travel
In the reporting year, four engineers each made one return flight to Edinburgh (short-haul, economy, ~600 km each way): - Return distance per trip: 1,200 km - 4 trips × 1,200 km × 0.255 kgCO2e/km ÷ 1,000 = 1.22 tCO2e
Three trips by UK national rail (average 400 km round trip): - 3 × 400 km × 0.035 kgCO2e/km ÷ 1,000 = 0.04 tCO2e
- Category 6 total: 1.26 tCO2e
Category 7 — Employee Commuting
22 employees, estimated average 24 km round-trip commute, 220 working days, 65% by car: - Car commuters: 22 × 0.65 × 24 km × 220 days × 0.170 kgCO2e/km ÷ 1,000 = 13.65 tCO2e - Remaining 35% by rail: 22 × 0.35 × 24 km × 220 days × 0.035 kgCO2e/km ÷ 1,000 = 1.41 tCO2e - Category 7 total: 15.06 tCO2e
Scope 3 total: 20.41 tCO2e
Complete Summary
| Scope | Source | tCO2e |
|---|---|---|
| Scope 1 | Gas + diesel van | 13.01 |
| Scope 2 | Electricity | 7.33 |
| Scope 3 | WTT + waste + travel + commuting | 20.41 |
| Total | 40.75 tCO2e |
Emissions intensity: 40.75 ÷ 22 employees = 1.85 tCO2e per employee — well within the typical range for UK engineering services SMEs (1.5–4.0 tCO2e/employee).
What to Write in the Questionnaire Methodology Box
> "GHG Protocol Corporate Standard (WRI/WBCSD). Emission factors: DEFRA 2023 (UK Government). Scope 1: natural gas combustion and diesel vehicle. Scope 2: purchased electricity, location-based, UK grid factor 0.193 kgCO2e/kWh. Scope 3: Category 3 (WTT from Scope 1 fuels), Category 5 (waste — contractor-reported tonnage), Category 6 (business travel — flight distances from booking records, rail by journey km), Category 7 (commuting — employee headcount × average commute estimate × 220 working days). Self-assessed. Reporting year: [YYYY]. Verification: [Carbon Passport URL]."
How DeCarbonOPS Replicates This
DeCarbonOPS applies exactly these DEFRA 2023 factors automatically. Enter your gas m³, electricity kWh, diesel litres, headcount, and travel estimates — the platform performs all the calculations above and generates a Carbon Passport with your Scope 1, 2, and 3 totals, intensity metrics, and a verification URL. The process takes under 20 minutes.
Frequently Asked Questions
What are the DEFRA 2023 factors used in this worked example?
The worked example uses: natural gas 2.04 kgCO2e/m³ (Scope 1), diesel 2.68 kgCO2e/litre (Scope 1), UK grid electricity 0.193 kgCO2e/kWh (Scope 2), natural gas WTT 0.376 kgCO2e/m³ (Scope 3 Cat 3), diesel WTT 0.641 kgCO2e/litre (Scope 3 Cat 3), landfill waste 0.459 kgCO2e/kg (Scope 3 Cat 5), short-haul economy flight 0.255 kgCO2e/km (Scope 3 Cat 6), UK rail 0.035 kgCO2e/km (Scope 3 Cat 6), and car commuting 0.170 kgCO2e/km (Scope 3 Cat 7).
Is 40.75 tCO2e a typical total for a 22-person engineering services company?
Yes, 40.75 tCO2e for a 22-person UK engineering services firm (1.85 tCO2e/employee) is within the normal range for the sector (1.5–4.0 tCO2e/employee). The figure would be higher for firms with more business travel, longer commutes, or more gas-intensive premises. It would be lower for home-working-heavy firms with low travel budgets.
Why is Scope 3 larger than Scope 1 and 2 combined in the example?
Employee commuting (15.06 tCO2e) is the largest single source in this example — larger than Scope 1 and 2 combined. This is typical for professional and engineering services firms where the main emission driver is people travelling rather than energy-intensive processes. Commuting and business travel often dominate Scope 3 for service businesses, while waste and WTT are relatively small.
How would the example change if the company switched to a renewable electricity tariff?
The Scope 2 market-based figure would drop to approximately zero (from 7.33 tCO2e) if the company switched to a REGO-backed renewable electricity tariff. This is the fastest single reduction available — free to implement, available on request from most UK electricity suppliers. The location-based Scope 2 (7.33 tCO2e) would still be reported for comparison, but the market-based figure is the one most buyers use.
Can DeCarbonOPS replicate this calculation automatically?
Yes. Enter the same inputs into DeCarbonOPS — gas m³, electricity kWh, diesel litres, waste tonnes, flight distances, rail distances, and commuting data — and it performs these calculations exactly, applying DEFRA 2023 factors for each source. The platform generates a Carbon Passport with all scope totals, intensity metrics, and a verification URL in under 20 minutes.
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