Every non-exact factor in this tool references one of these sources. We prioritise official standards, government and agency data, then international organisations and serious technical references — and we never invent numbers.
2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2 (Energy), Ch.1 & Ch.2
international organization
Publisher
IPCC / Institute for Global Environmental Strategies (IGES)
Reliability: Very high — the global Tier-1 default fallback for net calorific values (Vol.2 Ch.1 Table 1.2) and default CO2 emission factors (Vol.2 Ch.2 Table 2.2) when no better regional source exists. Used here as primary for crude oil, anthracite and lignite (rank-based, global), which DESNZ does not cover cleanly.
Ch.1 (NCV): https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_1_Ch1_Introduction.pdf ; Ch.2 (EF): https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_2_Ch2_Stationary_Combustion.pdf . Factors are in kg/TJ and NCVs in TJ/Gg (= GJ/tonne). 95% CI ranges recorded where given.
2025 Government GHG Conversion Factors for Company Reporting (Full Set)
government
Publisher
UK Department for Energy Security and Net Zero (DESNZ)
Year
2025
License
Open Government Licence v3.0 — explicit permission for commercial AND non-commercial reuse, adaptation and redistribution, with attribution ('Contains public sector information licensed under the Open Government Licence v3.0').
Retrieved
2026-07-04
Reliability: Very high — the single most valuable fuel source for this project: per-fuel density, NCV/GCV, CO2/CH4/N2O split and derived CO2e in one authoritative, actively maintained, licensing-friendly dataset. Data year 2025; next publication June 2026.
Full data set (Excel): https://assets.publishing.service.gov.uk/media/6846a4f55e92539572806125/ghg-conversion-factors-2025-full-set.xlsx . Fuel values were taken from its 'Fuels', 'Bioenergy', 'Fuel properties', 'UK electricity' and 'Outside of scopes' sheets. This is used as the general-purpose, UK-context default source.
US EPA — Emissions & Generation Resource Integrated Database (eGRID)
Year
2025
License
US federal government work — public domain, freely reusable
Retrieved
2026-08-17
Reliability: High — eGRID is the authoritative US inventory of power-plant emissions and generation, compiled from EPA CAMD, EIA and other federal reporting. This is the primary summary document (Rev. 2, created 03/27/2025, produced with eGRID R production model 1.0.2).
Table 1 (Subregion Output Emission Rates) and Table 3 (State Output Emission Rates) both carry an identical bottom "U.S." row; the national figures used here are taken from it. Rates are published in lb/MWh; this catalog stores g/kWh, converted with the exact NIST pound (0.45359237 kg) — see the factor notes for the arithmetic.
Energy units & calculators explained; Energy conversion calculators; CO2 emission coefficients
government
Publisher
US Energy Information Administration (EIA)
Year
2024
License
US federal government work — public domain
Retrieved
2026-07-04
Reliability: High — the standard US-specific cross-check for heat contents and CO2 coefficients. Heat-content data year varies by table (Monthly Energy Review Appendix A, annual); CO2 coefficients based on 2022 data, used for 2023+ estimates; page release date 2024-09-18.
CO2 coefficients: https://www.eia.gov/environment/emissions/co2_vol_mass.php ; conversion calculators: https://www.eia.gov/energyexplained/units-and-calculators/energy-conversion-calculators.php . Used only as a US cross-check figure in notes, never averaged with DESNZ/IPCC.
US federal government work — public domain, freely reusable
Retrieved
2026-07-04
Reliability: High — 435 factors, Scope 1/2/3, widely used for US corporate GHG reporting; stationary-combustion factors trace to 40 CFR Part 98 / EPA's GHG Inventory. Published Jan 2025 ('last modified 15 January 2025').
PDF: https://www.epa.gov/system/files/documents/2025-01/ghg-emission-factors-hub-2025.pdf ; XLSX: https://www.epa.gov/system/files/other-files/2025-01/ghg-emission-factors-hub-2025.xlsx . Table 6 holds eGRID electricity factors (US average). US-specific cross-check only in v0.1.
Greenhouse gas emission intensity of electricity generation in Europe
international organization
Publisher
European Environment Agency (EEA)
Year
2024
License
EEA content generally reusable with attribution (standard EU-institution practice); not explicitly re-verified on this page in the research pass.
Retrieved
2026-07-04
Reliability: Medium — good EU-aggregate cross-check for electricity carbon intensity. EU-27 2023 value 242 gCO2/kWh (down from 292 in 2022). The exact 2024 figure was not extractable from the fetched page; the 2023 figure is used with an explicit year caveat.
Used only for the illustrative, region+year-labeled EU electricity example — never as a default factor.
Guide for the Use of the International System of Units (SI), NIST Special Publication 811 (2008 edition)
standards body
Publisher
National Institute of Standards and Technology (NIST), US Dept. of Commerce
Year
2008
License
US federal government work — public domain, freely citable and reusable
Retrieved
2026-07-04
Reliability: Very high — the canonical US reference for SI usage and exact conversion factors. Defines BTU_IT (1.05505585262 kJ), cal_IT (4.1868 J), cal_th (4.184 J), the avoirdupois pound, US/imperial gallon and cubic foot. 2008 edition not yet updated for the 2019 SI redefinition (NIST's own note), which does not affect the mechanical conversion factors used here.
Appendix B lists the exact conversion factors used for lb, gallons, ft^3, cal_IT and BTU_IT. DOI 10.6028/NIST.SP.811e2008. PDF mirror: https://physics.nist.gov/cuu/pdf/sp811.pdf
Hydrogen Tools — Lower and Higher Heating Values of Hydrogen and Other Fuels; Basic Hydrogen Properties Chart
government lab
Publisher
Pacific Northwest National Laboratory (PNNL) for the US DOE Hydrogen Safety Panel / H2tools.org
Year
2016
License
US DOE-funded public resource — citable with attribution
Retrieved
2026-07-04
Reliability: High by reputation for hydrogen physical properties. The primary page still blocked automated fetch (HTTP 403) in the Data agent's follow-up pass. H2Tools republishes the DOE GREET / ORNL heating-value table; the fetchable primaries for these figures are that GREET/ORNL table and the NIST Chemistry WebBook (see nist-webbook). Values here are confirmed against those fetchable primaries, not recalled from memory.
Hydrogen: LHV 119.96 MJ/kg (~33.3 kWh/kg, NIST WebBook-traceable; DOE GREET gives 120.21), HHV 141.79 MJ/kg (~39.4 kWh/kg, NIST-printed; GREET gives 142.18), gas density 0.08988 kg/m³ at 0 °C/1 bar, liquid density 70.8 kg/m³ (NIST-precise 70.85) at boiling point (−252.87 °C). GREET/ORNL mirror: https://courses.grainger.illinois.edu/npre470/sp2018/web/Lower_and_Higher_Heating_Values_of_Gas_Liquid_and_Solid_Fuels.pdf ; basic properties chart: https://h2tools.org/basic-hydrogen-properties-chart
IEA Unit Converter (Data Tools) — energy-sector unit conventions (toe, tce)
international organization
Publisher
International Energy Agency (IEA)
Year
2023
License
CC BY 4.0 (the tool/page itself) — reusable with attribution. Distinct from IEA's paywalled statistical data products.
Retrieved
2026-07-04
Reliability: Medium-high for definitions (toe = 41.868 GJ net; tce = 29.3076 GJ). Tool last updated 30 Dec 2023. Shows no per-factor sourcing itself, so used only for the standard-definition energy-equivalence conventions.
The widely-cited IEA/UN conventions are: 1 toe = 41.868 GJ (derived from 10⁷ kilocalories, International Table definition, net basis), and 1 tce = 29.3076 GJ (7 gigacalories, IT). The IEA's 'World Energy Balances' dataset, which has detailed country-level data, sits behind a paywall and is not used as a numeric source here.
NIST Chemistry WebBook, NIST Standard Reference Database Number 69
standards body
Publisher
National Institute of Standards and Technology (NIST), US Dept. of Commerce
Year
2021
License
US federal government work — public domain, freely citable
Retrieved
2026-07-04
Reliability: Very high — the authoritative US thermochemical reference. Used for the NIST-traceable hydrogen heating values (LHV 119.96, HHV 141.79 MJ/kg, from the 25 °C heat-of-combustion / formation enthalpies) and hydrogen density (gas 0.08988 kg/m³, liquid 70.85 kg/m³ via NIST 'Thermophysical Properties of Hydrogen').
Used as the primary citation for hydrogen properties, since the H2Tools page could not be fetched automatically. This was confirmed on 2026-07-04 against NIST heat-of-combustion and thermophysical-property tables, and cross-checked against the DOE GREET/ORNL data (see the h2tools entry) — small differences of about 0.2% were found and were not averaged together.
Reliability: Normative project rulebook; records the definitional conventions (IT calorie/BTU, toe/tce/boe, therm, Julian year) v0.1 adopts. Used as a source_ref only for the project's chosen conventions where an external primary citation is also attached (nist-sp811 / iea-unit-conventions).
This is not an independent external authority — it is our own internal document recording which convention we chose to follow, alongside a pointer to the real external source. We keep it listed together with that external source wherever it applies.
#spec-conversion-rules
How these feed into results is described on the methodology page.