Scope 3 Category 3: Upstream Energy
Category 3 covers the emissions from extracting, processing, and transporting the fuels and energy you use — the upstream footprint of your Scope 1 and 2 energy consumption. It is often overlooked but can add 10–20% on top of your direct energy emissions, particularly for gas-intensive operations.
Category 3 covers the emissions from extracting, processing, and transporting the fuels and energy you use — the upstream footprint of your Scope 1 and 2 energy consumption. Category 3 covers the upstream lifecycle emissions associated with the fuels and energy consumed by the reporting company — but not counted in Scope 1 or 2.
What Category 3 covers and why it matters
Category 3 covers the upstream lifecycle emissions associated with the fuels and energy consumed by the reporting company — but not counted in Scope 1 or 2.
For Scope 1 fuel combustion: the combustion emission itself is Scope 1. The emissions from extracting the gas from the ground, processing it at a refinery, and transporting it through a pipeline to your facility are Category 3. These well-to-gate emissions can add 15–25% to the combustion emission for natural gas.
For Scope 2 purchased electricity: the generation emission is already in Scope 2 (location or market-based). The extraction and processing of the coal, gas, or uranium used to generate that electricity, and the transmission losses in the grid, are Category 3. For renewable electricity, Category 3 covers the manufacturing emissions of the solar panels or wind turbines and the construction of generation infrastructure.
For purchased heat and steam: same principle — the generation emission is Scope 2, the upstream fuel chain emission is Category 3.
Category 3 is frequently omitted from Scope 3 inventories because it feels redundant — you are already counting your fuel combustion in Scope 1. But Category 3 captures the systemic emission from the energy supply chain that Scope 1 and 2 miss. For gas-intensive operations with high fugitive methane in the upstream supply chain, Category 3 can be material.
Calculating Category 3 — well-to-tank factors
The calculation methodology for Category 3 uses well-to-tank (WTT) emission factors — these capture the upstream lifecycle emissions per unit of fuel or energy, from extraction through to delivery at the point of use.
WTT factors are available from DEFRA GHG Conversion Factors — the 'WTT fuels' tab provides factors for natural gas, diesel, petrol, LPG, coal, and other fuel types. These are expressed in kg CO2e per unit of fuel (per litre, per kWh, or per kg).
Calculation: Activity data (same as Scope 1 — fuel volumes consumed) × WTT emission factor = Category 3 emissions.
For purchased electricity (Category 3 component): use the WTT electricity factor from DEFRA — expressed as kg CO2e per kWh of electricity consumed. This represents the upstream fuel chain emission and transmission losses associated with each kWh consumed.
Total Category 3 = Sum of (fuel volume × WTT factor) for each fuel type + (electricity consumed × WTT electricity factor) + (heat and steam consumed × WTT heat factor).
Methane leakage and Category 3 materiality
The single largest driver of Category 3 significance is methane leakage from the natural gas supply chain. Methane (CH4) has a GWP100 of 27.9 under IPCC AR6 — meaning even small volumes of leaked methane have substantial CO2e impact.
US EPA estimates total US natural gas system methane leakage at approximately 1.4% of production. European pipeline systems have lower leakage rates than some upstream production regions — particularly Russian gas imports which historically had higher leakage rates from long-distance pipeline infrastructure.
For a company with significant natural gas consumption (manufacturing, food processing, heating-intensive buildings): Category 3 from gas supply chain methane can represent 15–30% of the total Scope 1 gas combustion emission on a CO2e basis. This is material and should not be excluded without assessment.
The transition away from natural gas — to heat pumps, hydrogen, or biomethane — reduces both Scope 1 combustion emissions and Category 3 upstream methane. This is an additional co-benefit of gas phase-out that strengthens the business case for electrification.
Frequently asked questions
Is Category 3 always calculated from the same activity data as Scope 1 and 2?
Yes — Category 3 uses the same fuel consumption data as Scope 1 (fuel volumes) and the same electricity/heat consumption data as Scope 2. The difference is the emission factor applied — combustion factors for Scope 1, grid factors for Scope 2, and WTT factors for Category 3. Collect the activity data once and apply multiple factor sets.
Do renewable energy purchases eliminate Category 3 for electricity?
Partially. Market-based Scope 2 can be reduced to near-zero through GOO purchases. Category 3 for electricity includes transmission and distribution losses and the manufacturing emissions of generation infrastructure — these are not zero even for renewable electricity. The Category 3 factor for renewable electricity is much lower than for fossil fuel electricity but not zero.
Should we report Category 3 separately from Scope 1 and 2 in our CSRD report?
Yes — ESRS E1-6 requires Scope 3 to be disclosed by category. Category 3 is a separate line item in your Scope 3 disclosure, not added to Scope 1 or 2. Some companies additionally show a 'well-to-wheel' or 'lifecycle' emission figure that combines Scope 1 and Category 3 for analytical purposes — this can be useful context but should not replace the standard scope-segregated disclosure.