GRI 305: what each emissions disclosure number means

The short version

This guide walks through GRI 305's numbered disclosures. For the underlying calculations, see Scope 1, 2 and 3, explained and the organization footprint calculator.

GRI 305 is the emissions-specific slice of the GRI Standards, the sustainability-reporting framework most widely referenced by stakeholders — customers, NGOs, investors — outside the newer climate-specific disclosure regimes. It is organized as seven numbered disclosures (305-1 through 305-7) plus a management-approach section, and unlike IFRS S2 it covers some environmental impacts — ozone-depleting substances, air pollutants — that have nothing to do with a carbon tonnage but everything to do with material environmental effect. This guide works through each disclosure against the section structure a report template built on GRI 305 actually uses.

305-1 — Direct (Scope 1) GHG emissions

The disclosure asks for absolute gross Scope 1 emissions in tCO2e, plus three things many first-time reporters omit:

• Which gases are included — CO2, methane, nitrous oxide, HFCs, PFCs, SF6, NF3. Most SME Scope 1 is CO2 from fuel combustion plus HFCs from refrigerant leaks; state which gases are actually present in your activities rather than listing all seven by default.
• The GWP source — the Global Warming Potential values used to convert non-CO2 gases into CO2-equivalent, typically an IPCC Assessment Report (AR5 or AR6). This matters because GWP values are periodically revised, and a refrigerant's CO2e figure changes slightly between AR5 and AR6.
• The consolidation approach for the organizational boundary — equity share, financial control, or operational control, same three options as under IFRS S2.

Evidence for 305-1 is the same paperwork covered in our Scope 1/2/3 guide: fuel receipts, fleet-card statements, and aircon servicing invoices showing refrigerant top-ups.

305-2 — Energy indirect (Scope 2) GHG emissions

305-2 asks for location-based Scope 2 (the grid-average factor for wherever you're connected — 0.4020 kgCO2e/kWh for Singapore's 2024 data year) and, where you hold contractual instruments — renewable energy certificates, guarantees of origin, power purchase agreements — the market-based figure alongside it. If you hold none, GRI expects you to say so explicitly: state that location-based and market-based are equal, rather than leaving the market-based line blank. See our Singapore grid emission factor guide for the full detail on which factor vintage applies to which reporting year.

305-3 — Other indirect (Scope 3) GHG emissions

305-3 asks for Scope 3 emissions by material GHG Protocol category, and — distinctly from IFRS S2's wording — explicitly asks you to disclose the methodology used to determine materiality, not just the resulting figures. A short paragraph naming which categories you screened, which you found material, and why (spend threshold, known supply-chain structure, prior-year data) satisfies this more completely than category totals alone.

305-4 — GHG emissions intensity

This is where GRI diverges most visibly from a pure tonnage report: 305-4 asks for an intensity ratio — emissions per unit of some organizational metric — with the denominator left to the reporter's choice. Common denominators are revenue, headcount, floor area, or units produced.

Worked intensity calculation: a light-manufacturing SME with 145.6 tCO2e total emissions (Scope 1 + 2 + 3) and S$9.7 million annual revenue:

Intensity = 145.6 tCO2e ÷ S$9.7 million = 15.0 tCO2e per S$1 million revenue

The same organization could instead report per employee — say, 42 staff:

Intensity = 145.6 tCO2e ÷ 42 employees = 3.47 tCO2e per employee

Both are valid 305-4 disclosures; GRI does not mandate one denominator over another. What it does ask is that you name the denominator and keep it consistent year to year, since an intensity ratio is only useful as a trend if the yardstick doesn't change underneath it.

305-5 — Reduction of GHG emissions

305-5 asks you to separate emissions reductions that came from actual reduction initiatives — switching to LED lighting, electrifying a delivery vehicle, sourcing renewable electricity — from reductions that happened for other reasons: lower output in a slow year, divesting a site, or a methodology change (a new emission factor vintage, for instance). The Singapore grid factor easing from 0.4085 to 0.4020 between data years is a useful illustration of the distinction this disclosure protects: a company whose Scope 2 tonnage fell only because of that factor update has not achieved a reduction under 305-5, even though its reported number is lower.

305-6 — Emissions of ozone-depleting substances

This disclosure has no IFRS S2 equivalent. It asks for production, imports, exports, and destruction of ozone-depleting substances (ODS) in metric tonnes of CFC-11-equivalent — relevant mainly to organizations running large refrigeration or air-conditioning fleets, or those in industries that manufacture or handle ODS directly. When an SME can honestly say "not material": if your only refrigerant-bearing equipment is a handful of office aircon units serviced occasionally (the same activity already covered under Scope 1 refrigerant leaks), the ODS-specific disclosure is appropriately marked not material — the leak itself still belongs in 305-1, but the dedicated ODS disclosure is a different, larger-scale reporting obligation aimed at bulk handlers.

305-7 — NOx, SOx, and other significant air emissions

Also with no IFRS S2 counterpart, 305-7 asks for significant air pollutants — NOx, SOx, persistent organic pollutants, particulate matter, heavy metals, volatile organic compounds — in kilograms or tonnes. This is squarely aimed at heavy manufacturing, power generation, and shipping, where combustion produces regulated air pollutants distinct from greenhouse gases. When an SME can say "not material": an office, retail, or professional-services operation with no on-site combustion beyond occasional generator use has no meaningful NOx/SOx profile to report; state that assessment plainly rather than omitting the disclosure number entirely, since a numbered "not material" statement is a complete disclosure and a missing section number reads as an oversight.

GRI 3-3 — Management of the material topic

Sitting alongside the seven numbered disclosures, GRI's management-approach disclosure (3-3, applied here to the emissions topic) asks for the same kind of methodological detail IFRS S2 asks for under §29(b)–(d): the GHG accounting standard used (GHG Protocol Corporate Standard, or ISO 14064-1), emission factor sources and versions, the GWP/IPCC Assessment Report applied, the consolidation approach, base year and recalculation policy, reporting period coverage, and activity data sources.

GRI vs IFRS S2: the practical differences

| | GRI 305 | IFRS S2 §29 | | --- | --- | --- | | Purpose | Sustainability reporting standard, broad stakeholder audience | Climate-specific financial disclosure standard, investor audience | | Scope 1/2/3 tonnage | Yes (305-1/2/3) | Yes (§29a) | | Intensity ratio | Explicit disclosure (305-4) | Not a numbered requirement | | ODS and air pollutants | Yes (305-6, 305-7) | No equivalent | | Biogenic CO2 | Not a separate numbered line | Separate disclosure required | | Measurement methodology | Under 3-3 management approach | Under §29(b)–(d), same level of detail | | Financed emissions | Not covered in 305 | §30, financial entities | | Targets | Covered under GRI 305-5 (reductions) and separate target standards | §32, with defined content requirements | | Adoption mechanism | Voluntary / stakeholder-requested, referenced by some regulators | Adopted into law or listing rules by jurisdiction (e.g. SGX) |

Neither framework asks for a different number underneath — Scope 1, 2 and 3 are computed the same way regardless of which standard's paragraph you're filling in. What differs is which additional context each standard expects around that number, and for whom.

A worked example: the full 305-1/2/3 set

A 25-person clinic operator, one reporting year, using figures from the organization footprint calculator:

• 305-1 (Scope 1): 1.8 tonnes of LPG for backup generator testing plus 1.2 kg of R-410A refilled during aircon servicing. LPG: 1,200 litres × 1.5594 kgCO2e/litre = 1,871 kgCO2e. Refrigerant: 1.2 × 1,924 kgCO2e/kg = 2,309 kgCO2e. Total Scope 1 ≈ 4.2 tCO2e.
• 305-2 (Scope 2): 46,000 kWh at Singapore's 2024 data-year factor: 46,000 × 0.4020 = 18,492 kgCO2e ≈ 18.5 tCO2e, location-based. No RECs held, so market-based is stated as equal.
• 305-3 (Scope 3): purchased medical consumables (spend-based estimate) and staff commuting, the two categories screened as material for a clinic of this size: 31.4 tCO2e combined.
• 305-4 (intensity): total of 54.1 tCO2e ÷ 25 staff = 2.16 tCO2e per employee.
• 305-6 and 305-7: both stated not material — no ODS handling beyond the aircon refrigerant already counted in 305-1, and no combustion source large enough to produce a meaningful NOx/SOx profile.

That is a complete seven-disclosure GRI 305 section: five populated figures, two honest "not material" statements, and one intensity ratio with its denominator named.

What this guide doesn't cover

• Full GRI Standards adoption. GRI 305 can be referenced on its own, as this guide treats it, but a "GRI-compliant" claim requires meeting GRI's broader reporting principles across all material topics, not just emissions.
• Assurance requirements. GRI 305 does not itself mandate external assurance; whichever regulation or exchange layers on top of it sets that separately.
• Sector-specific GRI standards. Some industries have their own GRI sector standards with additional emissions-adjacent disclosures beyond 305.

Sources

• GRI — GRI 305: Emissions 2016: globalreporting.org
• GHG Protocol — Corporate Standard and Scope 3 Standard: ghgprotocol.org
• SGX RegCo — Sustainability Reporting Guide (references GRI as a comparable framework): sgx.com/regulation
• IPCC — Assessment Report GWP values (AR5/AR6): ipcc.ch