Methodology · v2026.1

How CarbonTiers calculates emissions

Every tonne of CO₂e on the platform follows a transparent chain: activity data → emission factor → tier → GWP version. Built on IPCC 2006 (Vol. 1-5), GHG Protocol, ISO 14064-1:2018 and PCAF; ready for ISO 14064-3 verification.

IPCC 2006 (Vol. 1-5) GHG Protocol ISO 14064-1:2018 PCAF Cat. 15
5
IPCC sectors
32+
Sub-modules
3
Tier levels
15
Scope 3 categories

From activity data to report

Every tool follows the same four steps, and every choice you make along the way is kept with the result.

  1. Step 1

    Choose the boundary

    A single IPCC sector, the National Reporting Suite, a company (CarbonTrack) or a city (CityCarbon).

  2. Step 2

    Enter activity data

    Fuel, production, livestock, land area or waste in the module’s own units. Default factors come from the library with their source shown.

  3. Step 3

    Set tier and GWP

    Tier 1, 2 or 3 where the module supports it, and AR4, AR5 or AR6. Both are recorded against the result.

  4. Step 4

    Review and report

    Check the breakdown, then export. Each line keeps its activity data, factor, source, tier and GWP basis.

SECTION 01

Standards stack

CarbonTiers is built on three layers of internationally recognised methodology. They are complementary: IPCC defines the science, GHG Protocol defines the boundaries, ISO defines the reporting format.

Science

IPCC 2006 Guidelines

Volumes 1-5 covering Energy, IPPU, AFOLU, Waste with sectoral equations, default emission factors, and uncertainty ranges. Refined by IPCC 2019.

Boundaries

GHG Protocol Corporate

Scope 1 (direct), Scope 2 (location- and market-based), Scope 3 (15 categories). Sets organisational and operational boundaries for corporate inventories.

Reporting

ISO 14064-1:2018

Six-category indirect emission classification. Replaces the older Scope 1/2/3 split for ISO-conformant inventories. Verifiable per ISO 14064-3:2019.

SECTION 02

Tier 1 → Tier 3 progression

The IPCC tier framework defines methodological complexity and accuracy. CarbonTiers records the tier used for every line item, so verifiers see exactly which factor came from which source.

Level 1
Tier 1

IPCC default factors

Global default emission factors and parameters from IPCC 2006 Guidelines. Suitable when activity data is limited or for first-time inventories.

  • Fuel combustion: IPCC default EF by fuel type
  • Enteric fermentation: regional default EF (kg CH₄/head/yr)
  • Cement: 0.51 t CO₂ / t clinker default
Level 2
Tier 2

Country-specific factors

Jurisdiction-specific factors from official transmission operators, energy agencies, and national inventory reports. Higher accuracy than Tier 1.

  • Grid electricity: TEIAS, EPA eGRID, DEFRA, UBA, RTE
  • Cattle: country-specific feed digestibility & live weights
  • Industrial process: national-average plant data
Level 3
Tier 3

Plant-level / measured

Direct measurement, continuous emission monitoring (CEMS), or facility-specific factors. Highest accuracy, required for CBAM and verified ETS reporting.

  • CEMS-derived stack CO₂ / NOx
  • Plant-specific clinker chemistry (CaO content)
  • Process model output (e.g., DAYCENT for soils)
SECTION 03

GWP: AR4 / AR5 / AR6

Global Warming Potentials are not constants - each IPCC assessment report updates the values. CarbonTiers lets you pick AR4, AR5, or AR6 (100-year horizon) and applies it consistently. The selected version is recorded on every CO₂e output for verification.

GasAR4 (2007)AR5 (2013)AR6 (2021)
CO₂111
CH₄ (fossil)252829.8
CH₄ (biogenic)——27
N₂O298265273
HFC-134a1,4301,3001,530
HFC-2314,80012,40014,600
SF₆22,80023,50024,300
NF₃17,20016,10017,400
CF₄7,3906,6307,380

100-year time horizon. UNFCCC reporting required AR4 until 2020; most national inventories now use AR5; AR6 adoption is growing for voluntary disclosure (CDP, SBTi).

SECTION 04

Sectoral methodology

Each of the five IPCC sectors has its own equations, default factors, and tier rules. The platform implements them volume-by-volume, chapter-by-chapter, with the canonical reference next to each line.

IPCC 2006 Vol. 2

Energy

Fuel combustion (stationary + mobile), fugitive emissions from oil/gas/coal, and carbon capture & storage.

Modules
  • •Stationary Combustion (40+ fuels)
  • •Mobile Combustion (road, rail, air, water)
  • •Fugitive (oil, gas, coal mining)
  • •Reference Approach (apparent consumption)
  • •CCS (CO₂ transport & storage)
Core equations
E = AD × EF (Tier 1)
E = AD × EF country-specific (Tier 2)
E = AD × EF plant-specific, with CO₂ oxidation factor (Tier 3)
Reference
IPCC Vol. 2 Ch. 2-4
IPCC 2006 Vol. 3

IPPU

Industrial Processes and Product Use. Mineral (cement, lime, glass), chemical (ammonia, nitric acid), metal (iron & steel, aluminium), and 15 fluorinated gases.

Modules
  • •2A Mineral (cement, lime, glass, soda ash)
  • •2B Chemical (ammonia, HNO3, adipic, carbides)
  • •2C Metal (iron & steel, aluminium, lead, zinc)
  • •2D Non-Energy Products from Fuels
  • •2E Electronics (integrated circuits, TFT)
  • •2F F-gases (15 HFC/PFC, SF6, NF3)
Core equations
E_CO2 = M_clinker × EF_clinker × CKD surcharge (2A1)
E_N2O = M_HNO3 × EF_process (2B2)
E_HFC = M_product × EF_product × GWP (2F)
Reference
IPCC Vol. 3 Ch. 2-5; EU CBAM Implementing Regulation
IPCC 2006 Vol. 4 (AFOLU)

Agriculture

Enteric fermentation, manure management, rice cultivation, managed soils (direct + indirect N₂O), and field burning of agricultural residues.

Modules
  • •Enteric Fermentation (20+ animal categories)
  • •Manure Management (11 systems × 3 climate bands)
  • •Rice Cultivation (7 water regimes)
  • •Managed Soils (direct + indirect N₂O)
  • •Biomass Burning (residues)
Core equations
Enteric CH₄: E = (N_animal × EF) / 1000 (eq. 10.19)
Manure CH₄: E = VS × Bo × MCF (eq. 10.23)
Direct soil N₂O: E = (Σ(F_SN + F_ON + F_CR + F_SOM) × EF1) × 44/28
Rice CH₄: E = A × t × EF_i × SFw × SFp × SFo
Reference
IPCC Vol. 4 Ch. 10-11
IPCC 2006 Vol. 4 Ch. 4-9

LULUCF

Land Use, Land-Use Change and Forestry. Stock-difference and gain-loss methods across forest land, cropland, grassland, wetlands, settlements, and harvested wood products.

Modules
  • •Forest Land (12 ecological zones)
  • •Cropland SOC
  • •Grassland SOC
  • •Wetlands & Peatlands
  • •Settlements
  • •Other Land
  • •HWP (5 approaches: SCA/AFA/PA/SDA/FOD)
Core equations
Stock-difference: ΔC = (C_t2 - C_t1) / (t2 - t1)
Gain-Loss: ΔC = Σ(ΔC_AB + ΔC_BB + ΔC_DW + ΔC_LI + ΔC_SO)
HWP (FOD): C(t) = e^(-k) × C(t-1) + ((1-e^(-k))/k) × Inflow(t)
Reference
IPCC Vol. 4 Ch. 4-9, 12 (HWP)
IPCC 2006 Vol. 5

Waste

Solid waste disposal (FOD model), biological treatment, incineration, and wastewater (domestic + industrial pathways).

Modules
  • •Solid Waste Disposal (FOD, 7 types × 6 SWDS × 5 climate zones)
  • •Biological Treatment (composting, anaerobic digestion)
  • •Waste Incineration (7 technology types)
  • •Wastewater (14 domestic + 10 industrial pathways)
Core equations
SWDS (FOD): CH₄ = Σ ((1-f) × MSW × DOC × DOC_f × MCF × F × 16/12 - R) × (1-OX)
Wastewater: CH₄ = (TOW - S) × EF - R
Incineration: CO₂ = SW × dm × CF × FCF × OF × 44/12
Reference
IPCC Vol. 5 Ch. 2-6
SECTION 05

Scope mapping & ISO categories

The platform classifies every line by both the GHG Protocol scope and the ISO 14064-1:2018 indirect category. This dual mapping lets you produce both reporting formats from the same inventory without rework.

GHG Protocol scopes

Scope 1 - direct
Stationary combustion, mobile combustion, fugitive, process emissions.
Scope 2 - imported energy
Electricity, steam, heating, cooling. Reported dual: location- and market-based.
Scope 3 - value chain
15 categories spanning upstream and downstream activities (incl. PCAF Cat. 15).

ISO 14064-1:2018 categories

  • 1Direct GHG emissions and removals (= Scope 1)
  • 2Indirect GHG emissions from imported energy (= Scope 2)
  • 3Indirect from transportation
  • 4Indirect from products used by the organization
  • 5Indirect associated with the use of products from the organization
  • 6Indirect from other sources

Scope 3 - 15 categories

1. Purchased goods and services
2. Capital goods
3. Fuel- and energy-related activities
4. Upstream transportation and distribution
5. Waste generated in operations
6. Business travel
7. Employee commuting
8. Upstream leased assets
9. Downstream transportation and distribution
10. Processing of sold products
11. Use of sold products
12. End-of-life treatment of sold products
13. Downstream leased assets
14. Franchises
15. Investments (PCAF)
SECTION 06

Scope 2 dual reporting

GHG Protocol Scope 2 Guidance (2015) requires both a location-based and market-based total. The platform calculates both automatically.

Location-based

Average grid intensity for the country/region in which the consumption physically occurs.

E = kWh × EF_grid_country
Sources: TEIAS, EPA eGRID, DEFRA, UBA, RTE, IEA, NDRC, CEA

Market-based

Contractual instruments (PPAs, RECs, GoOs) reflecting your specific energy supplier choices.

E = Σ(kWh_i × EF_supplier_i) + (residual × EF_residual)
Quality criteria per Scope 2 Guidance §7.1
SECTION 07

PCAF - financed emissions

For financial institutions, Scope 3 Category 15 (Investments) is calculated per the PCAF Global GHG Accounting and Reporting Standard.

Attribution
Financed emissions = Σ (Outstanding amount_c / EVIC_c) × Emissions_c

For listed equity & corporate bonds: attribution factor = outstanding amount ÷ EVIC (Enterprise Value Including Cash). For project finance, business loans, mortgages, motor vehicle loans, commercial real estate, and sovereign debt, the platform implements the asset-class-specific PCAF formulas.

PCAF data score 1-2
Verified emissions reported by counterparty (preferred)
PCAF data score 3
Physical activity-based estimate
PCAF data score 4-5
Sector-average / economic activity-based estimate
SECTION 08

Uncertainty & data quality

Each line item carries a Data Quality Indicator (DQI) score. The platform aggregates uncertainty using IPCC Approach 1 (error propagation) and supports Monte Carlo (Approach 2) on Pro plans.

5
Direct measurement / CEMS data, current period
4
Plant-specific factor, current period
3
Country-specific factor, recent (< 5 yr)
2
IPCC default, regional context
1
IPCC default, global average, > 5 yr old
Approach 1
Error propagation
Combine uncertainty ranges via standard formulas. Suitable for any inventory.
Approach 2
Monte Carlo
Where you have run your own Monte Carlo analysis, record the method and resulting ranges per scope in the corporate inventory's uncertainty section.
SECTION 09

Scenario modelling math

Project emissions forward against five built-in pathways or design custom scenarios from the 81+ mitigation options across the five sectors. All scenarios share the same baseline year and end year for clean comparison.

Business as Usual (BAU)

E(t) = E(t₀) × (1 + g)^(t - t₀)

Project current activity growth forward at constant rate g. Used as the no-action reference baseline.

IPCC 1.5 °C (AR6)

Linear path to net-zero by 2050; -7% / yr global reduction

AR6-aligned trajectory. Roughly 50% reduction by 2030 vs. 2019 baseline, net-zero CO₂ by mid-century.

IPCC 2 °C

Net-zero CO₂ by ~2070; -3% / yr

Paris-compatible likely-below 2 °C trajectory. Less aggressive than 1.5 °C path.

EU ETS Fit-for-55

LRF 4.3% (2024-27) → 4.4% (2028-30); -62% by 2030 vs 2005

Linear Reduction Factor schedule from EU ETS Directive. Used for installations under EU ETS or CBAM.

Custom mitigation

E(t) = E_BAU(t) - Σ(M_i × A_i(t))

Stack 81+ mitigation options across the 5 sectors with start year, ramp curve, and abatement potential. Compare against BAU and IPCC pathways side-by-side.

Five interpolation methods

Linear (constant slope)Step (annual targets)Logistic (S-curve adoption)Exponential decayCustom polynomial
SECTION 10

Audit traceability

Every tonne of CO₂e on the platform traces back through a five-step chain. Verifiers receive a single inventory summary that maps to GHG Protocol scopes and ISO 14064 categories simultaneously.

Activity data
Emission factor
Tier (1/2/3)
GWP version
CO₂e output

Source citation

Every emission factor links to its publisher (TEIAS, IPCC table ref, DEFRA dataset etc.).

Version pinning

GWP version, factor publication year, and IPCC volume reference are stored on every line.

Export formats

Excel, PDF, Word, CSV, XML and chart images, depending on the tool. CRT tables for national inventories.

SECTION 11

Grid factor library

Multi-country grid emission factors sourced from official transmission operators and energy agencies. Used for Scope 2 location-based calculations.

Grid Emission Factor Library

208 countries and regions · 213 distinct vintage entries · sourced from national authorities.

Country / regionLatest yearEF (tCO₂/MWh)SourceVintages
Turkey20250.4360ÇŞİDB6
EU-27 average20220.2760IEA1
Germany20220.3850UBA1
France20220.0560RTE1
United Kingdom20240.2070DEFRA1
United States20220.3860EPA eGRID1
Japan20220.4700MoE Japan1
China20210.5810NDRC1
India20220.7080CEA1
Austria20230.1100Ember1
Belgium20230.1370Ember1
Bulgaria20230.3720Ember1
Croatia20230.1440Ember1
Cyprus20230.5730Ember1
Czechia20230.4020Ember1
Denmark20230.1450Ember1
Estonia20230.4270Ember1
Finland20230.0620Ember1
Greece20230.3180Ember1
Hungary20230.1900Ember1
Ireland20230.2810Ember1
Italy20230.2680Ember1
Latvia20230.1320Ember1
Lithuania20230.1450Ember1
Luxembourg20230.0980Ember1
Malta20230.4100Ember1
Netherlands20230.2680Ember1
Poland20230.6100Ember1
Portugal20230.1280Ember1
Romania20230.2430Ember1
Slovakia20230.1080Ember1
Slovenia20230.2080Ember1
Spain20230.1520Ember1
Sweden20230.0320Ember1
Norway20230.0300Ember1
Switzerland20230.0410Ember1
Iceland20230.0280Ember1
Serbia20230.6800Ember1
Bosnia and Herzegovina20230.7000Ember1
North Macedonia20230.6000Ember1
Albania20230.0240Ember1
Montenegro20230.4000Ember1
Kosovo20230.9000Ember1
Moldova20230.5200Ember1
Ukraine20230.2300Ember1
Russia20230.3600Ember1
Georgia20230.1500Ember1
Canada20230.1250Ember1
Mexico20230.4230Ember1
Brazil20230.0980Ember1
Argentina20230.3340Ember1
Chile20230.3360Ember1
Colombia20230.1960Ember1
Peru20230.2340Ember1
Australia20230.5480Ember1
New Zealand20230.1040Ember1
South Korea20230.4370Ember1
Indonesia20230.6780Ember1
Vietnam20230.3970Ember1
Thailand20230.4720Ember1
Malaysia20230.5500Ember1
Philippines20230.6110Ember1
Pakistan20230.4000Ember1
Bangladesh20230.5200Ember1
Kazakhstan20230.7600Ember1
South Africa20230.7090Ember1
Egypt20230.4460Ember1
Morocco20230.6100Ember1
Nigeria20230.3860Ember1
Kenya20230.0960Ember1
Ghana20230.4120Ember1
Ethiopia20230.0260Ember1
Tanzania20230.3950Ember1
Saudi Arabia20230.6290Ember1
United Arab Emirates20230.3960Ember1
Qatar20230.4900Ember1
Israel20230.5310Ember1
Jordan20230.4300Ember1
Azerbaijan20230.5100Ember1
Afghanistan20240.1172Ember1
Antigua and Barbuda20240.6081Ember1
Armenia20250.2440Ember1
Angola20240.1851Ember1
American Samoa20240.6222Ember1
Aruba20240.5490Ember1
Barbados20240.6009Ember1
Burkina Faso20240.5609Ember1
Bahrain20240.9025Ember1
Burundi20240.1837Ember1
Benin20240.5792Ember1
Brunei Darussalam20240.8930Ember1
Bolivia20250.4814Ember1
Bahamas20240.6524Ember1
Bhutan20240.0237Ember1
Botswana20240.8525Ember1
Belarus20250.3163Ember1
Belize20240.1702Ember1
Congo (DRC)20240.0276Ember1
Central African Republic20230.0214Ember1
Congo20240.7156Ember1
Cote d'Ivoire20240.4056Ember1
Cook Islands (the)20240.3500Ember1
Cameroon20240.2262Ember1
Cuba20240.6429Ember1
Cabo Verde20240.4635Ember1
Djibouti20240.4300Ember1
Dominica20230.5733Ember1
Dominican Republic20250.5380Ember1
Algeria20240.6328Ember1
Ecuador20250.1588Ember1
Eritrea20240.5911Ember1
Fiji20240.2757Ember1
Falkland Islands (Malvinas)20230.7000Ember1
Faroe Islands20230.3612Ember1
Gabon20240.5254Ember1
Grenada20240.6583Ember1
French Guiana20230.2571Ember1
Greenland20240.1383Ember1
Gambia20240.6588Ember1
Guinea20240.1814Ember1
Guadeloupe20230.4934Ember1
Equatorial Guinea20240.6430Ember1
Guatemala20240.3015Ember1
Guam20240.6054Ember1
Guinea-Bissau20240.6625Ember1
Guyana20240.6420Ember1
Hong Kong (SAR of China)20240.6756Ember1
Honduras20240.3220Ember1
Haiti20240.5395Ember1
Iraq20240.6831Ember1
Iran20250.6560Ember1
Jamaica20240.5624Ember1
Kyrgyzstan20250.0726Ember1
Cambodia20250.4988Ember1
Kiribati20240.5000Ember1
Comoros20230.6571Ember1
Saint Kitts and Nevis20240.6043Ember1
North Korea20240.3406Ember1
Kuwait20250.6347Ember1
Cayman Islands20240.6324Ember1
Lao PDR20240.2321Ember1
Lebanon20240.3882Ember1
Saint Lucia20240.6425Ember1
Sri Lanka20250.3677Ember1
Liberia20240.3140Ember1
Libya20240.8269Ember1
Madagascar20240.4337Ember1
Mali20240.5374Ember1
Myanmar20240.5023Ember1
Mongolia20250.8218Ember1
Macao (SAR of China)20240.4744Ember1
Martinique20230.5265Ember1
Mauritania20240.5150Ember1
Montserrat20240.7000Ember1
Mauritius20240.6422Ember1
Maldives20240.6153Ember1
Malawi20240.0568Ember1
Mozambique20240.1294Ember1
Namibia20240.0524Ember1
New Caledonia20240.5641Ember1
Niger20240.6705Ember1
Nicaragua20240.3004Ember1
Nepal20240.0240Ember1
Nauru20240.5400Ember1
Oman20250.5444Ember1
Panama20240.2203Ember1
French Polynesia20240.4403Ember1
Papua New Guinea20240.5161Ember1
Saint Pierre and Miquelon20230.6600Ember1
Puerto Rico20250.6561Ember1
Palestine (State of)20240.4172Ember1
Paraguay20250.0248Ember1
Reunion20230.3987Ember1
Rwanda20240.3619Ember1
Solomon Islands20240.6000Ember1
Seychelles20240.5603Ember1
Sudan20240.1543Ember1
Singapore20250.4970Ember1
Sierra Leone20240.0571Ember1
Senegal20240.5401Ember1
Somalia20240.5302Ember1
Suriname20240.3230Ember1
South Sudan20240.6464Ember1
Sao Tome and Principe20230.5889Ember1
El Salvador20250.1113Ember1
Syria20240.7062Ember1
Eswatini20240.1197Ember1
Turks and Caicos Islands20240.6370Ember1
Chad20240.6297Ember1
Togo20240.4211Ember1
Tajikistan20250.0726Ember1
Turkmenistan20241.3062Ember1
Tunisia20250.5602Ember1
Tonga20240.5714Ember1
Trinidad and Tobago20240.6813Ember1
Taiwan (China)20250.6336Ember1
Uganda20240.0585Ember1
Uruguay20250.0802Ember1
Uzbekistan20251.0000Ember1
Saint Vincent and the Grenadines20240.5733Ember1
Venezuela20240.0859Ember1
Virgin Islands (British)20230.6588Ember1
Virgin Islands (U.S.)20230.6397Ember1
Vanuatu20230.5000Ember1
Samoa20240.4000Ember1
Yemen20240.5914Ember1
Zambia20240.1258Ember1
Zimbabwe20240.3837Ember1

1st priority: National transmission operators (TSO) and official registries (TEIAS, RTE, EPA eGRID, DEFRA, UBA, NDRC, MoE Japan, CEA).

2nd priority: IEA Emissions Factors annual bulletin and EU-27 averages.

This table updates automatically as new countries or vintages are added.

SECTION 12

References & sources

All standards, datasets, and grid factor sources used by the platform.

•IPCC 2006 Guidelines for National GHG Inventories (Vol. 1-5)
•IPCC 2019 Refinement to the 2006 Guidelines
•IPCC AR4 / AR5 / AR6 (WG1) - GWP values
•GHG Protocol Corporate Standard (revised 2015)
•GHG Protocol Scope 2 Guidance (2015)
•GHG Protocol Corporate Value Chain (Scope 3) Standard
•ISO 14064-1:2018 - Organization-level GHG quantification
•ISO 14064-2:2019 - Project-level GHG quantification
•ISO 14064-3:2019 - Verification & validation
•PCAF Global GHG Accounting Standard for Financial Industry
•EU CBAM Implementing Regulation 2023/1773
•EU ETS Directive 2003/87/EC (revised 2023, Fit-for-55)
•UNFCCC ETF Reporting Tools - Common Reporting Tables (CRT)
•TEIAS - Turkish grid emission factor
•EPA eGRID - US grid factors
•DEFRA - UK conversion factors
•UBA - German grid factors
•RTE - French grid factors
•IEA Emissions Factors database
•NDRC - China grid factors
•CEA - India grid factors
•MoE Japan - Japanese grid factors

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