A buyer's ESG questionnaire asks a manufacturer for its carbon footprint. The inputs are utility bills and fuel records; the method is multiplication by published emission factors. No consultant is required for a site-level Scope 1 and 2 figure.
| First question | Short answer |
|---|---|
| What do I calculate? | Scope 1 (fuel you burn: gas, diesel, LPG, refrigerant leaks) and Scope 2 (electricity you buy). |
| What data do I need? | Twelve months of electricity (kWh), gas (m³ or kWh), and fuel (liters), by site. |
| Where do the factors come from? | National grid factors (IEA, DEFRA, EPA) for electricity; DEFRA or national factors for fuels. Use the current year's. |
| What do customers accept? | A company-level Scope 1 and 2 figure with the period, boundary, inputs, factors, and method stated. |
| Product-level? | A separate calculation; see the product carbon footprint guide. |
Scope 1 and Scope 2
Scope 1: direct emissions from sources you control — natural gas boilers and process heat, company vehicles and forklifts, refrigerant leaks.
Scope 2: indirect emissions from purchased electricity and heat.
Manufacturers start with these two because the data is on bills they already receive.
Electricity (Scope 2)
The electricity bill shows kilowatt-hours consumed.
Formula: kWh × grid emission factor = kg CO₂e
Example
A facility used 50,000 kWh in a month. The grid factor for its country is 0.420 kg CO₂e/kWh.
50,000 kWh × 0.420 = 21,000 kg CO₂e = 21 metric tons CO₂e
Grid factors by country
Grid factors vary widely with the generation mix. Approximate values, for illustration only — use the current published factor for your reporting year:
- France: ~0.05 kg CO₂e/kWh (nuclear-heavy)
- Germany: ~0.42 kg CO₂e/kWh
- Poland: ~0.78 kg CO₂e/kWh (coal-heavy)
- United States: ~0.39 kg CO₂e/kWh (national average)
- China: ~0.56 kg CO₂e/kWh
- India: ~0.71 kg CO₂e/kWh
Find the factor in the IEA emission factors database or the UK DEFRA conversion factors, which cover most grids. The free Scope 2 calculator applies a current grid factor when you enter kWh.
Natural gas (Scope 1)
Gas bills show consumption in cubic meters, therms, or kWh.
Per m³: m³ × 2.02 kg CO₂e/m³
Per therm: therms × 5.50 kg CO₂e/therm
Example
A factory used 5,000 m³ of natural gas for heating and process heat in a month.
5,000 m³ × 2.02 = 10,100 kg CO₂e = 10.1 metric tons CO₂e
Fleet and equipment fuel (Scope 1)
Fuel consumption from fuel cards, receipts, or fleet records.
- Diesel: liters × 2.69 kg CO₂e/L
- Petrol: liters × 2.31 kg CO₂e/L
- Propane (LPG): liters × 1.51 kg CO₂e/L
Example
A delivery fleet consumed 800 liters of diesel in a month.
800 L × 2.69 = 2,152 kg CO₂e = 2.15 metric tons CO₂e
The total
For the example month:
- Electricity: 21.0 metric tons CO₂e
- Natural gas: 10.1 metric tons CO₂e
- Fleet diesel: 2.15 metric tons CO₂e
Total: 33.25 metric tons CO₂e per month, roughly 399 metric tons CO₂e per year at that rate.
The factors above are illustrative. The free carbon calculator runs the full calculation — electricity, gas, fleet fuel — from the same inputs with current factors.
Reporting the result
Present both:
- Absolute emissions: total metric tons CO₂e per year
- Emissions intensity: metric tons CO₂e per unit of production — per metric ton of product, per unit, per euro of revenue, or per square meter
ESG Passport stores the calculation and drafts it into questionnaire responses, so the figure is not recalculated for each buyer.
Improving accuracy
- Track monthly to see seasonal patterns.
- Update emission factors annually as grids decarbonize.
- Sub-meter high-energy processes.
- Document the methodology so an auditor can follow it.
- Set reduction targets from the baseline.
Common errors
Outdated factors. Grid factors change yearly as renewables are added. Use the factor for the reporting year.
Mixing location-based and market-based. For Scope 2, location-based uses the grid average; market-based uses your supplier's specific rate. Be consistent, and state which.
Forgetting refrigerants. Cooling systems leak refrigerant. The gases have very high global warming potential and are Scope 1.
Ignoring small sources. Process emissions, welding gases, and backup generators count.
What customers accept
For a first supplier response, most customers accept a company-level Scope 1 and 2 footprint if the calculation is transparent. Include the reporting year, organizational boundary, energy and fuel activity data, the emission factors used, and whether electricity was calculated location-based or market-based. If product-level emissions are not yet calculated, say so and state when allocation by product line is planned. The product carbon footprint guide covers the step from site footprint to per-product figure.
A credible response needs traceability, not software. Keep the utility bills, fuel invoices, meter readings, emission-factor source, and calculation spreadsheet together. If a customer challenges the number, each input and formula should be visible without rebuilding the calculation.
Documenting the method
Write a short methodology note alongside the calculation: sites included, sources excluded, reporting period, units, who reviewed the figures, version date. This turns a spreadsheet into evidence. For multiple facilities, keep one worksheet per site and one summary worksheet.
For product manufacturers, record the production denominator used for intensity. Customers may ask for emissions per metric ton, per unit, per batch, or per euro of revenue. Choose the denominator that matches how the customer buys from you, and keep the production report behind it. This explains changes in emissions when output rises or falls.