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
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)253029.8
CH₄ (non-fossil)252827
N₂O298265273
HFC-134a1,4301,3001,530
HFC-2314,80012,40014,600
SF₆22,80023,50025,200
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
10,000 iterations sampling from distribution of each input. Pro plan.
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 an immutable 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, PNG, SVG, JSON. CRF templates available 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

9 countries and regions · 12 distinct vintage entries · sourced from national authorities.

Country / regionLatest yearEF (tCO₂/MWh)SourceVintages
Turkey20250.4360TEİAŞ4
EU-27 average20220.2760IEA1
Germany20220.3850UBA1
France20220.0560RTE1
United Kingdom20240.2070DEFRA1
United States20220.3860EPA eGRID1
Japan20220.4700MoE Japan1
China20210.5810NDRC1
India20220.7080CEA1

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 CRF Reporter - National inventory templates
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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Methodology | CarbonTiers