Value chain · Scope 3
Scope 3: travel, freight, materials and waste
Seven kinds of value-chain activity are entered by picking a published activity from a catalogue and supplying the one or two numbers its basis needs. The factor covers the whole activity.
On this page you'll learn
- Which Scope 3 categories Slate covers, and their bases
- Why freight is costed per tonne-kilometre
- How two publishers' waste catalogues are kept apart
- Scope
- 3 (categories 1, 4, 5, 6, 7, 8, 9)
- Catalogue
- 659 entries from DEFRA 2026, plus EPA waste
- Upstream
- Travel and freight only
The seven entry kinds
| Entry kind | You enter | Basis | GHG Protocol category |
|---|---|---|---|
| Business travel | Journey type, passengers, distance | passenger-km or km | 6 |
| Freight | Vehicle and load, mass, distance | tonne-km or km | 4 (upstream) or 9 (downstream) |
| Managed assets | Leased vehicle, distance | km | 8 |
| Hotel stays | Country, room-nights | room-night | 6 |
| Homeworking | Full-time-equivalent hours | FTE working hour | 7 |
| Material use | Material, tonnes | tonne | 1 |
| Waste disposal | Material and route, tonnes | tonne | 5 |
The catalogue is generated from an imported release, never typed by hand: 659 entries from DEFRA 2026's 1,023 Scope 3 activities. The 350 left out are paths DEFRA lists without a value; offering them would put choices in the picker that always fail.
The basis is a decision
Publishers often publish the same activity on more than one basis, and they aren't interchangeable. DEFRA's Class I diesel van:
- Per tonne-km: 20 × 200 × 0.87948
- 3,518 kg CO₂e
- Per vehicle-km: 200 × 0.15833
- 32 kg CO₂e
- Slate uses
- per tonne-km: 3,518 kg
Both look reasonable in a table. The catalogue used to pick whichever sorted first alphabetically, which put every road-freight entry on the vehicle basis.
Freight prefers tonne-km
What a shipment emits depends on how much of the vehicle it used. It's the basis the GHG Protocol transport guidance and DEFRA's methodology treat as standard.
Taxis prefer km
DEFRA's per-passenger taxi figure assumes shared occupancy. A business taxi is usually hired whole, so the passenger basis would cut every journey by about 29% for passengers who weren't there.
Upstream for travel and freight
DEFRA publishes well-to-tank factors for business travel and freight only. Hotels, homeworking and managed assets have none, and material and waste factors are already cradle-to-grave. The upstream row is matched to the direct row on the same basis: pairing a tonne-km direct factor with a vehicle-km upstream one would describe two different journeys as one. All 262 travel and freight activities with a value link cleanly.
Two publishers, two waste catalogues
Waste disposal is offered from DEFRA (42 materials, 4 routes) and from EPA Hub Table 9 (62 materials, 5 routes). They are not alternatives: EPA's landfill figure reflects US landfill-gas capture, DEFRA's reflects UK practice, and the materials don't correspond one to one.
So each entry records which publisher's vocabulary it came from, and your organisation only sees entries its source chain can price. A DEFRA-only organisation never sees an EPA waste row it couldn't calculate.
Why this matters
Waste you send away is Scope 3 here. A landfill you operate is Scope 1 and uses IPCC's decay model: see Operated landfill. The two must never be added for the same site. And WARM scenario figures are never part of either: see EPA WARM.
Room-nights and FTE hours
These are counts, not measurements. They convert to nothing, deliberately: there is no room-night in a kilogram, and a converter that offered one would be inventing it.