The Emission Factor Library

GreenSphere's Emission Factor Library is the database of vetted emission factors used to calculate every emissions value in the platform. This guide covers what's in it, where the factors come from, how they're structured for audit, and how to add your own when you need to.

Where to find it

When you land on the Emissions page, you see an overview of your emissions for the selected period — total emissions broken down by scope, plus trend and category views. Switch to the Emission Factors tab to access the library itself.

What's in the library

Over 5,000 emission factors, drawn primarily from two authoritative sources:

• DEFRA — the UK government's annual conversion factors. Covers detailed activity-based factors across stationary combustion, mobile combustion (road, rail, sea, air), refrigerants, materials, waste, freight, business travel, and more. Updated annually; widely used internationally as a reference set.
• EMBER — global grid emission factors covering ~99 countries. The standard for location-based Scope 2 calculations outside the UK and US. Updated annually as grids decarbonise.

Each factor is structured with the same set of fields (see Drill-down below) so the library is searchable, filterable, and consistent.

Categorisation: up to five levels

Every factor is categorised across up to five category levels (Level 1 → Level 5). The deeper levels disambiguate similar factors. For example:

• Level 1: Business travel
• Level 2: Air
• Level 3: Flights
• Level 4: International short-haul out UK
• Level 5: Average passenger – With RF

This hierarchy makes the library navigable: filter to Level 1 = "Business travel" to see everything in that domain; drill deeper to find the specific factor that matches your activity.

The drill-down: what each factor shows

Click into any factor and the detail panel on the right shows the full audit-ready record:

• Factor name — e.g., Business travel — Air — Flights — International short-haul — Average passenger — With RF.
• Emission factor value — e.g., 100 kgCO₂e / m³, with the value and the per-unit denominator.
• Description — what the factor measures and how to apply it.
• Activity unit — the unit your activity data should be in (e.g., m³, kWh, km, kg). The platform converts on entry; this is the factor's reference unit.
• GWP basis — which IPCC Assessment Report the global warming potentials come from (AR4, AR5, AR6, or SAR). AR6 is the current standard; older factors may use AR5 or AR4. Mixing GWP bases within a single inventory is generally avoided.
• Source & provenance — the source body (DEFRA, EMBER, etc.), the version year (e.g., DEFRA 2024), the geography it applies to, and an updated timestamp.
• Factor ID — the unique identifier you can cite in audit notes and assurance documentation.
• Gas breakdown (where applicable) — the underlying CO₂, CH₄, and N₂O components, combined into the headline CO₂e figure using the relevant GWP basis.

This level of detail is the differentiator. Most platforms surface the factor value and the source name; few expose the gas breakdown, version, GWP basis, and factor ID inline. Assurance reviewers ask for all of it.

Searching, filtering, and browsing

The factor list is searchable and filterable across the categorisation levels and metadata fields. Use it to:

• Find the right factor for a specific activity — search by activity (e.g., "flights international short-haul") or by category (e.g., Level 1 = Business travel).
• Filter by source — when you need DEFRA-specific factors for a UK-aligned report, or EMBER specifically for grid factors.
• Filter by geography — to verify country-specific factor coverage before logging.
• Filter by version year — when a methodology change requires a specific year's factors (e.g., DEFRA 2024 for FY 2024 reporting).

Custom emission factors

If the factor you need isn't in the library — or if you have supplier-specific or company-specific data — create a custom factor.

Click + Create Custom Emission Factor on the Emission Factors tab. The Create Emission Factor page has four sections:

Identity & classification

• Factor name (required) — e.g., Natural Gas Combustion — Office Boilers.
• Description (optional) — when and how this factor should be applied.
• Geography (optional) — e.g., United Kingdom, Global.
• Source (optional) — e.g., DEFRA 2024, EPA, supplier name.
• Version (optional) — e.g., 2024.1.
• Categories — up to five levels (Level 1 through Level 5). Mirrors the structure used by the standard library.

Emission values

• CO₂e (required) — the total greenhouse gas factor expressed as CO₂ equivalent. This is the number used in all calculations.
• Individual gases (optional) — separate CO₂, CH₄, and N₂O values in kg. Useful when you want the gas breakdown surfaced in audit detail.
• GWP basis (optional) — choose AR4, AR5, AR6, or SAR. AR6 is the current standard; the platform notes this on the form. Match the basis used by the source you're drawing from.

Units

• Activity data unit — the unit of the raw data input (e.g., litres, kWh, kg). What your data will be entered in.
• Emission factor unit — the denominator unit for the factor (e.g., per litre, per kWh, per kg).

Notes

• Free text for assumptions, caveats, methodology notes, or supplier-provided detail. This is what auditors and future editors see when reviewing the factor.

Click Save custom factor. The factor now appears in the library alongside standard factors, available for selection from the Emissions Impact section on Log Data and from custom data-point mappings.

Mapping factors to data points

Every emission factor — whether standard or custom — can be mapped to a specific raw data point so that the correct factor automatically appears (or is applied) when data is logged against that data point in future.

Set up the mapping on the Emissions page (or inline on the data point's drill-down on the Raw Data page). Once mapped, logging is faster and more consistent: the scope, category, and factor auto-fill on every new entry.

Mappings are also a documented methodology choice. "All grid electricity in Kenya uses the EMBER Kenya grid factor, AR6 GWP basis, three-year average vintage" applied uniformly via a mapping is much cleaner audit evidence than ad-hoc per-entry factor selection.

You can override the mapping per-entry if needed — useful when a specific reporting period uses a different factor (e.g., a different vintage, or a supplier-specific factor for a single contract).

Versioning, vintages, and updates

DEFRA and EMBER both update annually. When a new version lands in the library:

• Existing entries don't recalculate retroactively. A factor used at the time of entry is the factor that's locked into the audit trail — assurance evidence stays defensible.
• New entries get the latest version by default. Unless you've pinned a specific version via mapping, the most recent factor for the geography is used.
• You can pin a vintage. For multi-year reporting where consistency matters more than recency, configure the mapping to use a specific version year.

This versioning behaviour is what makes year-on-year comparison defensible. If you switch versions mid-year, document the change in audit notes — assurance providers will ask.

Where to go from here

• How emissions calculations work — the calculation chain that uses these factors.
• Audit trail and data history — how every factor selection and version is logged.
• Log your first data point — the workflow where you'll select factors in practice.
• For methodology depth: Location-based vs market-based Scope 2: which to use and when in the reporting guides — when you need to think about which factor to use and why.