Liquefied Petroleum Gas (LPG)
Every forklift fleet, every off-grid commercial heating system, every hospitality kitchen running propane burners has the same accounting decision: which LPG factor, which unit, which scope. The wrong choice is rarely a rounding error — it is usually a 5–10% mis-statement of the Scope 1 inventory line that LPG occupies.
LPG looks like a simple fuel until the invoice arrives in tonnes, the meter reads in kWh, the technical datasheet specifies propane purity, and the supplier ships a 60/40 propane/butane blend. The DEFRA 2026 factor is unambiguous — but only if the question being asked of it is unambiguous first.
LPG (liquefied petroleum gas) is a propane/butane blend. Combustion in owned equipment is Scope 1; the well-to-tank supply chain is Scope 3 Category 3a. The DEFRA 2026 factor for blended LPG is 1.55713 kg CO₂e per litre — but compare fuels per kWh, not per litre.
What LPG Is and What It Is Not
LPG (Liquefied Petroleum Gas) is a category covering propane (C₃H₈), butane (C₄H₁₀), and blends of the two. Both gases are byproducts of natural gas processing and crude oil refining. At ambient pressure they are gaseous; under modest pressure (around 2 bar for butane, 8 bar for propane) they liquefy, which is why they are transportable as liquid in cylinders and bulk tanks. On combustion they revert to gas and burn cleanly with no soot and very low particulate output — which is why they dominate forklift fleets, off-grid heating, and indoor hospitality applications where diesel or solid fuels would be unacceptable.
Three disambiguations matter for GHG accounting:
LPG is not natural gas. Natural gas is primarily methane (CH₄) delivered through pipeline. LPG is propane/butane delivered as compressed liquid. Different molecule, different emission factor, different scope-3 supply chain. Confusing the two is the most common LPG accounting error — see Natural Gas.
LPG is not always propane. “Propane” in colloquial use is often shorthand for LPG, but the DEFRA factor for pure propane (1.54358 kg CO₂e/litre [GreenCalculus fuels.gbr.propane.litre]) differs from the blended LPG factor (1.55713 [GreenCalculus fuels.gbr.lpg.litre · DEFRA 2026 'Fuels'!D36]) and from pure butane (1.74533 [GreenCalculus fuels.gbr.butane.litre]). The right factor depends on what the supplier actually delivers.
LPG is not LNG. Liquefied Natural Gas (LNG) is methane cooled to −162°C. Liquefied Petroleum Gas is propane/butane compressed at ambient temperature. The shared “L” causes regular confusion in international procurement records.
The DEFRA 2026 Emission Factors — and How LPG Compares to Other Fuels
DEFRA publishes LPG emission factors in three units — per litre, per tonne, and per kWh — because LPG arrives invoiced in all three depending on supplier and region. All three are pre-aggregated CO₂e factors: the CO₂, CH₄, and N₂O components from combustion have already been multiplied by their GWP-100 values and summed by DEFRA. Practitioners multiply activity by the factor and get CO₂e directly.
| Fuel | kg CO₂e per litre | kg CO₂e per tonne | kg CO₂e per kWh (GCV) | kg CO₂e per kWh (NCV) |
|---|---|---|---|---|
| LPG (blended) | 1.55713 | 2939.36095 | 0.2145 | 0.23032 |
| Propane (pure) | 1.54358 | 2997.63233 | 0.2141 | 0.23258 |
| Butane (pure) | 1.74533 | 3033.38067 | 0.22241 | 0.24107 |
Source: DEFRA UK Government GHG Conversion Factors for Company Reporting 2025 (DESNZ, June 2025). Pre-aggregated CO₂e — AR5 GWP-100 basis per DEFRA convention. See complete DEFRA dataset →
How LPG compares to other Scope 1 fuels
The fairest comparison is per kWh of useful energy, not per litre. A litre of LPG, a litre of diesel, and a kWh of natural gas deliver very different quantities of energy — comparing them at the per-litre level is meaningless. The bar chart below normalises every fuel to kg CO₂e per kWh on a net calorific value (NCV) basis — the basis used for energy benchmarking under ISO 14064-1 and most regulatory thresholds.
Natural gas, diesel, petrol, and coal values derived from DEFRA 2026 headline factors divided by NCV — verified against MasterBrain v2026.182. Blended LPG, propane, and butane values live via MasterBrain shortcode.
Three takeaways for practitioners choosing between fuels:
- LPG is roughly 22% more carbon-intensive than natural gas per kWh delivered. The advantage of natural gas comes from a higher hydrogen-to-carbon ratio in methane (CH₄) than in propane (C₃H₈) or butane (C₄H₁₀) — more energy released per gram of CO₂ produced.
- LPG is roughly 22% less carbon-intensive than diesel per kWh delivered. Which makes LPG forklifts a genuine Scope 1 reduction lever against diesel forklifts, before any consideration of local air-quality co-benefits.
- The propane–butane spread is small per kWh (around 4%) but material per litre (around 13%). The unit chosen for the calculation determines whether the propane/butane distinction shows up in the inventory total.
Which Unit Is on Your Invoice — Per Litre, Per Tonne, Per kWh
LPG arrives invoiced in four units depending on supplier, country, and equipment type. Choosing the wrong unit field from DEFRA is the second-largest source of LPG reporting error, after using the natural gas factor by accident. The lookup table below maps every common invoice format to the right DEFRA field.
| Invoice / meter unit | DEFRA field to use | Blended LPG value | Typical context |
|---|---|---|---|
| Litres (L) | factor | 1.55713 | Forklift refuelling, small bulk tank deliveries |
| Tonnes (t) or kilograms (kg) | per_tonne | 2939.36095 | Bulk industrial supply, process feedstock |
| kWh gross calorific value | per_kwh_gcv | 0.2145 | UK metered LPG (matches gas convention) |
| kWh net calorific value | per_kwh_ncv | 0.23032 | ISO 14064 energy benchmarking, EU industrial |
Gross Calorific Value (GCV, also “higher heating value”) includes the latent heat of water vapour condensation. Net Calorific Value (NCV, also “lower heating value”) excludes it. The GCV/NCV ratio for LPG is approximately 1.09 — so a GCV-basis kWh figure is around 9% larger than the same energy expressed in NCV. Applying a GCV-basis emission factor to NCV-basis energy data (or vice versa) produces a roughly 9–10% error. Always confirm which basis the meter or invoice uses before selecting the DEFRA field. The UK convention for billed gas is GCV; the EU ETS and ISO 14064 convention for industrial energy is NCV.
Where LPG Sits in Scope Accounting — and a Worked Forklift Example
LPG combustion in owned or controlled equipment is Scope 1 under the GHG Protocol Corporate Standard — specifically stationary combustion for heating boilers and process burners, and mobile combustion for forklifts and small ICE vehicles. The well-to-tank supply chain (extraction, refining, transport, distribution) is Scope 3 Category 3a under the Scope 3 Standard.
Scope 1 — combustion
Forklifts, mobile plant, water heaters, space heaters, kitchen burners, process burners, off-grid generators. Owned or under operational control. Use the DEFRA combustion factor: 1.55713 kg CO₂e/litre [GreenCalculus fuels.gbr.lpg.litre].
Scope 3 Cat 3a — well-to-tank
Upstream emissions from LPG extraction, refining, and transport to the point of consumption. DEFRA publishes a WTT factor of approximately 0.387 kg CO₂e/litre — roughly 25% additional on top of the combustion factor. Hardcoded — no shortcode yet.
Scope 2 — not applicable
LPG is never Scope 2. Scope 2 covers purchased grid electricity, heat, steam, and cooling delivered through a utility network. LPG is a physical fuel delivered as a tradeable commodity, combusted on site.
Worked example: 24-forklift LPG fleet — annual Scope 1 + Scope 3 Cat 3a
A distribution centre operates 24 LPG forklifts on a single 8-hour shift, five days a week, 50 weeks a year. Average consumption: 3.2 litres per operating hour. Compute the annual Scope 1 combustion emissions and the Scope 3 Category 3a well-to-tank emissions.
| Step | Input or formula | Value | Source |
|---|---|---|---|
| 1. Fleet size | Number of forklifts | 24 | Operations data |
| 2. Operating hours per forklift | 8 h/day × 5 days × 50 weeks | 2,000 h/yr | Operations data |
| 3. Consumption rate | Manufacturer / metering | 3.2 L/h | Equipment spec |
| 4. Total annual LPG consumed | 24 × 2,000 × 3.2 | 153,600 L | Derived |
| 5. Scope 1 combustion | 153,600 × 1.55713 | 239,175 kg CO₂e | DEFRA 2026 blended LPG |
| 6. Scope 3 Cat 3a (WTT) | 153,600 × 0.387 | 59,443 kg CO₂e | DEFRA 2026 WTT-LPG |
| 7. Combined LPG footprint | Sum of rows 5 and 6 | 298,618 kg CO₂e | Derived |
All values in the worked example are hardcoded so it remains a reproducible snapshot regardless of future MasterBrain updates. The DEFRA 2026 blended LPG combustion factor used is 1.55713 kg CO₂e/litre; the WTT factor is 0.387 kg CO₂e/litre. Run the same scenario interactively in the Scope 1 Combustion Calculator.
Pre-aggregated CO₂e — what is already inside the LPG factor
The 1.55713 kg CO₂e/litre [GreenCalculus fuels.gbr.lpg.litre] figure looks like one number but is actually three. DEFRA composes the factor from the CO₂, CH₄, and N₂O combustion components, each multiplied by its GWP-100, and sums them at publication. The breakdown below — accessible in the MasterBrain via fuels.lpg.components — explains the structure.
| Component | Gas mass per litre LPG | GWP-100 (AR5) | Contribution (kg CO₂e/L) |
|---|---|---|---|
| CO₂ (combustion) | ~1.5510 kg CO₂/L | 1 | 1.5510 |
| CH₄ (slip) | ~0.000043 kg CH₄/L | 28 | 0.0012 |
| N₂O | ~0.000019 kg N₂O/L | 265 | 0.0050 |
| Sum — DEFRA pre-aggregated factor | 1.55713 | ||
Component values approximated from DEFRA 2026 source workbook; the headline figure 1.55713 is exact. Note DEFRA’s stated GWP basis is AR5 — see Mistake #4 for the AR5 vs AR6 reconciliation.
The DEFRA LPG factor is already in CO₂e form — the GWP arithmetic was performed at publication. Multiplying CH₄ slip × 29.8 [GreenCalculus gwp.CH4_fossil.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100] and adding it on top of the 1.55713 [GreenCalculus fuels.gbr.lpg.litre] figure double-counts the methane component. The same applies to N₂O. Use raw component factors only if you are deliberately building from a per-gas dataset (such as IPCC Tier 1 defaults) — and in that case, do not also use the pre-aggregated DEFRA figure. The two paths are mutually exclusive.
Calculate LPG combustion emissions across multi-fuel fleets with per-gas breakdown and audit-grade trail.
Propane, Butane, or Blended LPG — When the Distinction Matters
Most operators receive LPG as a propane/butane blend, and most use the DEFRA blended LPG factor (1.55713 kg CO₂e/litre) [GreenCalculus fuels.gbr.lpg.litre]. For the majority of reporting situations this is correct. But four contexts make the propane/butane distinction material.
| Context | Use propane factor | Use butane factor | Use blended LPG factor |
|---|---|---|---|
| Forklift fleet, generic supply | ✓ | ||
| Off-grid heating, generic supply | ✓ | ||
| Pure propane supply (verified by spec) | ✓ | ||
| Pure butane supply (verified by spec) | ✓ | ||
| Process feedstock — petrochemical | If propane | If butane | |
| DEFRA Tier 2 reporting / regulatory | If propane | If butane | If blend |
| Cylinder gas (often pure propane in UK) | ✓ | ||
| Aerosol propellant, lighter fuel (butane) | ✓ |
The per-litre spread between the three factors is material:
- Propane to blended LPG: 1.54358 [GreenCalculus fuels.gbr.propane.litre] vs 1.55713 [GreenCalculus fuels.gbr.lpg.litre] — about 0.9% lower
- Blended LPG to butane: 1.55713 [GreenCalculus fuels.gbr.lpg.litre] vs 1.74533 [GreenCalculus fuels.gbr.butane.litre] — about 12% higher for butane
- Propane to butane: 1.54358 [GreenCalculus fuels.gbr.propane.litre] vs 1.74533 [GreenCalculus fuels.gbr.butane.litre] — about 13% higher for butane per litre
The propane–butane spread comes from molecular structure: butane (C₄H₁₀) is a larger molecule with more carbon per litre than propane (C₃H₈). At equal volume, a litre of butane contains more carbon mass, so combustion releases more CO₂ per litre. On a per-kWh basis the spread narrows to around 4% because butane also carries more energy per litre.
Three sources, in order of authority: (1) the supplier’s Safety Data Sheet (SDS / MSDS) — Section 3 (Composition) lists the propane and butane content as percentages. (2) the technical data sheet attached to the bulk delivery note — most UK and EU LPG suppliers publish this monthly and it states the actual delivered blend ratio for the period. (3) the equipment manual — forklift and burner manufacturers usually specify the LPG grade their equipment is rated for, which is a strong inference about what is being delivered. If none of these are available, the blended LPG factor is the defensible default.
Four Common LPG Reporting Mistakes
- Using the natural gas factor for LPG by accident. Procurement records sometimes label LPG cylinders as “gas” and the inventory builder pulls the natural gas factor (2.02633 kg CO₂e/kWh [GreenCalculus fuels.gbr.natural_gas.m3 · DEFRA 2026 'Fuels'!D40] on a GCV basis) instead of the LPG factor (0.2145 kg CO₂e/kWh [GreenCalculus fuels.gbr.lpg.kwh_gcv · DEFRA 2026 'Fuels'!D38] on a GCV basis). Per kWh GCV, the LPG factor is roughly 22% higher — using the natural gas factor by mistake under-states the LPG line by approximately 18%. The two fuels are chemically distinct: methane (CH₄) for natural gas, propane/butane (C₃H₈/C₄H₁₀) for LPG.
- Mixing the unit basis — per litre, per tonne, per kWh GCV, per kWh NCV. DEFRA publishes all four. Multiplying activity in NCV-basis kWh by a GCV-basis factor (or vice versa) creates an approximately 9% error. Multiplying a tonnage by the per-litre factor creates an approximately 1,800× error. The unit on the invoice and the field selected from DEFRA must match exactly. See the §3 lookup table above.
- Ignoring well-to-tank (Scope 3 Category 3a). The DEFRA WTT factor for LPG is approximately 0.387 kg CO₂e/litre — roughly 25% of the combustion factor. A company that reports Scope 1 LPG but omits Scope 3 Cat 3a is missing about a quarter of the actual LPG footprint. Under the Scope 3 Standard Category 3 is required where material; for any fuel-intensive operation it almost always is.
- Reconciling AR5 (DEFRA) and AR6 (corporate inventory) bases incorrectly. DEFRA’s stated GWP basis on the source workbook is AR5. The corporate inventory default for every framework — GHG Protocol, CSRD/ESRS E1, CDP, SBTi — is AR6. The DEFRA factor is pre-aggregated and the AR5 basis is baked into its definition. Do not “convert” the DEFRA factor to AR6 by applying a 29.8/28 [GreenCalculus gwp.CH4_fossil.ar6_100] ratio to a CH₄ slip component that has already been collapsed into the headline figure. Use the DEFRA factor as published, and disclose its AR5 basis as an explanatory note on the methodology page. The practical effect of the AR5/AR6 distinction on LPG combustion is sub-1% because the non-CO₂ components (CH₄ slip + N₂O) contribute less than 0.5% of the headline factor — but the methodological discipline matters for audit. See the full reconciliation rule on CO₂e and GWP.
Related Terms, Standards, and Tools
Quick converters: LPG is billed by the litre, delivered by the kilogram and metered as energy — convert litres of LPG to kg or kg of LPG to kWh.
Frequently Asked Questions
LPG combustion in owned or controlled equipment is Scope 1 — specifically stationary combustion (heating boilers, process burners, kitchen equipment) or mobile combustion (forklifts, small ICE vehicles). LPG is never Scope 2; Scope 2 covers purchased grid electricity, heat, steam, and cooling delivered through utility networks. The upstream supply chain (extraction, refining, transport of LPG to the point of use) is Scope 3 Category 3a “Fuel- and energy-related activities — well-to-tank” under the GHG Protocol Scope 3 Standard — roughly 25% additional on top of the Scope 1 LPG line and required where material.
The DEFRA 2026 emission factor for blended LPG is 1.55713 kg CO₂e per litre [GreenCalculus fuels.gbr.lpg.litre]. Pure propane is 1.54358 kg CO₂e/litre [GreenCalculus fuels.gbr.propane.litre] and pure butane is 1.74533 kg CO₂e/litre [GreenCalculus fuels.gbr.butane.litre]. The blended value sits closer to propane than to butane because UK commercial LPG supply is propane-dominant. All three are pre-aggregated CO₂e factors — the CO₂, CH₄, and N₂O combustion components have already been multiplied by their GWP-100 values and summed at publication. The figures use AR5 GWP-100 per DEFRA convention; the practical difference vs AR6 is sub-1% for LPG. Source: DEFRA UK Government GHG Conversion Factors 2026.
On a per-kWh NCV basis — the fair comparison for energy benchmarking — LPG is roughly 22% more carbon-intensive than natural gas. Blended LPG is approximately 0.23032 kg CO₂e per kWh NCV [GreenCalculus fuels.gbr.lpg.kwh_ncv · DEFRA 2026 'Fuels'!D37]; natural gas is approximately 0.203 kg CO₂e per kWh NCV. The difference comes from molecular structure: methane (CH₄) in natural gas has a higher hydrogen-to-carbon ratio than propane (C₃H₈) or butane (C₄H₁₀) in LPG, so combustion releases less CO₂ per unit of energy delivered. Comparing per litre is meaningless because the two fuels deliver very different energy per litre — always normalise to per kWh (and confirm GCV vs NCV basis) before comparing.
Five steps. (1) Identify the unit on the invoice or meter — litres, tonnes, kWh GCV, or kWh NCV. (2) Select the matching DEFRA field: factor for litres, per_tonne for tonnes/kg, per_kwh_gcv for GCV-basis energy, per_kwh_ncv for NCV-basis energy. (3) Confirm whether the supply is blended LPG, pure propane, or pure butane (Safety Data Sheet Section 3 has the composition). For generic commercial supply, use the blended LPG factor. (4) Multiply activity by the factor to get Scope 1 combustion CO₂e. (5) Apply the WTT factor (approximately 0.387 kg CO₂e/litre) to the same activity for Scope 3 Category 3a. Disclose both lines separately in the inventory and cite DEFRA 2026 as the factor source. For a worked-out example see §3 above, or run the calculation interactively in the Scope 1 Combustion Calculator.
For most operators using generic commercial LPG supply — forklift fleets, off-grid heating, hospitality — the blended LPG factor (1.55713 kg CO₂e/litre [GreenCalculus fuels.gbr.lpg.litre]) is correct. For four contexts the distinction matters: (1) verified pure-propane or pure-butane supply (use 1.54358 [GreenCalculus fuels.gbr.propane.litre] or 1.74533 [GreenCalculus fuels.gbr.butane.litre] respectively); (2) petrochemical process feedstock where the gas grade is specified; (3) DEFRA Tier 2 or regulatory reporting requiring component-level accuracy; (4) UK cylinder gas, which is often pure propane. The per-litre spread between propane and butane is around 13%, so the choice of factor is material for high-volume operations. Confirm the actual delivered blend via the supplier’s SDS Section 3 or delivery-note technical data sheet before deviating from the blended default.
Build LPG reporting on DEFRA 2026 with full propane/butane/blended factor coverage, per-gas breakdown, and Scope 1 + Scope 3 Cat 3a in one workflow.
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