Business Travel (Scope 3 Category 6) — Definition and GHG Accounting Context
A single long-haul flight can outweigh a year of an employee’s commuting, heating, and office energy combined. For professional-services firms, banks, and consultancies — organisations with little in the way of factories or fleets — the emissions of getting people to meetings, sites, and conferences are often the largest controllable slice of the whole inventory.
Scope 3 Category 6 is where that travel is counted: the emissions of moving employees for business, in vehicles someone else operates — and the hotel rooms those trips fill.
Scope 3 Category 6 (business travel) covers the emissions from transporting employees for work in third-party vehicles — flights, rail, taxis, rental and personal cars used for business — plus, where included, the hotel stays those trips require. Travel is measured in passenger-kilometres; aviation carries a radiative-forcing uplift for its effects at altitude. It is distinct from Category 7 (employee commuting).
Definition — What Category 6 Covers
The GHG Protocol Scope 3 Standard defines Category 6, business travel, as the greenhouse gas emissions from the transportation of employees for business-related activities, in vehicles owned or operated by third parties. That spans air travel, rail, buses and coaches, taxis and ride-hailing, ferries, and rental or personal cars used for business trips. The standard also recommends — and most companies now include — the emissions of the accommodation those trips require, counted per hotel room-night.
Because the aircraft, train, or taxi is operated by someone else, these are indirect emissions in the company’s value chain. A car the company owns and an employee drives is Scope 1 instead; Category 6 is travel in vehicles the company does not operate. Travel undertaken by an employee’s own car for business is included here, typically reimbursed by mileage and converted with a per-kilometre factor.
Category 6 is work trips — flights to meetings, rail to a client site, a taxi to the airport, a hotel for a conference. It is not the daily journey between home and a regular workplace; that is Category 7, employee commuting, a separate category.
Business Travel vs Commuting (Cat 6 vs Cat 7)
The boundary companies most often blur is between Category 6 and Category 7. Both move employees, but they answer different questions:
| Category 6 — Business Travel | Category 7 — Employee Commuting | |
|---|---|---|
| What it covers | Travel for work — meetings, sites, conferences | Regular travel between home and workplace |
| Typical modes | Flights, rail, taxis, rental & personal cars, ferries | Car, bus, rail, cycling, walking; home-working energy |
| Accommodation | Hotel stays included (recommended) | Not applicable |
| Who arranges it | The company (booked / reimbursed) | The employee’s own routine |
A flight to a client in another country is Category 6; the daily drive to the office is Category 7. The distinction matters because the two categories draw on different data — travel-booking and expense records for business travel, employee surveys and headcount for commuting — and are usually owned by different teams.
Emissions by Travel Mode
Business travel is measured in passenger-kilometres — one passenger carried one kilometre — multiplied by a mode-specific factor in kg CO₂e per passenger-km, on a well-to-wheel basis. The gap between modes is large, and it is the single biggest lever a travel policy has. The chart below draws live from the DEFRA 2026 factor set (air shown with radiative forcing included).
Bar widths are proportional to intensity (domestic air = 100%). Values render live from DEFRA 2026, AR5 100-year GWP basis. Domestic flights are the most intense per passenger-km because take-off and climb dominate a short trip; a taxi carries only one or two people, so it rivals flying; rail is an order of magnitude lower. Cabin class matters too — a business- or first-class seat occupies more of the aircraft, so DEFRA multiplies the economy factor (roughly ×1.5 to ×4) for premium cabins.
Radiative Forcing: Why Aviation Is Worse Than Its CO₂
Aircraft do not only emit CO₂. At cruising altitude they produce contrails, water vapour, and nitrogen oxides that trap additional heat — a warming effect over and above the carbon dioxide from the fuel. This is radiative forcing, and the GHG Protocol and DEFRA both recommend including it for business-travel aviation.
DEFRA publishes each aviation factor twice — with and without the radiative-forcing uplift — so the difference is explicit. On the long-haul average, the factor rises from 0.09043 without RF to 0.15282 with RF, an uplift of roughly 70%.
Using the without-RF factor understates aviation’s real climate impact by around 40%. The recommended practice is to report business-travel flights with the radiative-forcing uplift, and to state which basis is used. Comparing a with-RF figure against a without-RF one — for instance across two years — is a common and misleading error.
Hotel Stays and Accommodation
The GHG Protocol recommends including the emissions of overnight accommodation within Category 6, because a multi-day business trip is as much about the nights as the miles. Hotel emissions are measured per room-night and vary widely by country, driven by the local grid, climate, and hotel type — a room-night in a hot country reliant on air-conditioning and a fossil-heavy grid can carry several times the footprint of one in a temperate, low-carbon market.
Estimate accommodation with country- and class-specific room-night factors in the hotel-stay calculator, and travel legs in the air and rail business-travel calculators.
How Category 6 Emissions Are Estimated
The GHG Protocol sets out three methods, from most to least specific. In practice most companies use the distance-based method against their travel-booking data, refining the largest flights with fuel-based figures where an airline or booking tool provides them.
| Method | Data used | Data quality | Best for |
|---|---|---|---|
| Fuel-based | Fuel use allocated to the passenger (e.g. airline or booking-tool data) | Highest | Flights where a carrier reports per-passenger fuel |
| Distance-based | Passenger-km by mode and class × a DEFRA/ICAO factor | Medium | The workhorse — travel-booking and itinerary data |
| Spend-based (EEIO) | Travel spend × a sector emission intensity | Lowest | Screening, or where only expense totals exist |
The distance-based method dominates because travel data usually arrives as itineraries — origin, destination, cabin class — which convert cleanly to passenger-km. See the full aviation approach, including the great-circle distance correction, in the air business-travel methodology and IATA RP 1726.
Worked Micro-Example
An employee flies economy on a 5,000 km long-haul return trip (10,000 passenger-km in total) and stays three nights in a hotel. (Factors are the live DEFRA values above; hotel figure illustrative.)
Flight = 10,000 pax·km × 0.15282 kg CO₂e/pax·km (long-haul, economy, with RF) = 1,528 kg CO₂e ≈ 1.53 tCO₂e
Without radiative forcing it would read 10,000 × 0.09043 = 0.90 tCO₂e — understating the trip by ~40%
Hotel = 3 room-nights × ~15 kg CO₂e/room-night ≈ 45 kg CO₂e (country-specific)
Trip total ≈ 1.57 tCO₂e, dominated by the flight
Booked to Category 6; the same employee’s daily commute would be Category 7
The example shows why aviation dominates: a single long-haul return trip outweighs the hotel nights many times over, and the radiative-forcing choice alone moves the flight figure by nearly half.
Common Confusions
- Confusing it with commuting. Business travel is work trips; the regular home-to-workplace journey is Category 7.
- Dropping radiative forcing. Report aviation with the RF uplift; omitting it understates flights by around 40%.
- Mixing RF bases. Never compare a with-RF figure against a without-RF one — state and hold one basis.
- Ignoring cabin class. Business and first class occupy more of the aircraft, so their per-passenger factor is a multiple of economy.
- Forgetting hotels. Accommodation is recommended in Category 6 and can be a meaningful share of a multi-day trip.
- Putting the company car here. A vehicle the company owns and operates is Scope 1; a personal car used for business is Category 6.
- Double-counting the taxi to the airport. Count each leg once; a taxi is business travel, not separately also freight or commuting.
Related Terms, Standards, and Tools
Category 6 sits in the transport cluster — the passenger-kilometre unit and radiative forcing it depends on, the DEFRA and IATA factors behind it, and the air, rail, and hotel calculators that quantify it.
Frequently Asked Questions
Scope 3 Category 6 is the greenhouse gas emissions from transporting employees for business activities in vehicles operated by third parties — flights, rail, buses, taxis, ferries, and rental or personal cars used for work — plus, where included, the hotel stays those trips require. Travel is measured in passenger-kilometres and accommodation in room-nights. Because the vehicle is operated by someone else, the emissions are indirect and reported in the company’s Scope 3 inventory. A vehicle the company owns and operates is Scope 1 instead.
Business travel (Category 6) is travel for work — flights to meetings, rail to a client site, a taxi to the airport. Employee commuting (Category 7) is the regular journey between an employee’s home and their workplace. The two are separate categories because they draw on different data: travel-booking and expense records for business travel, employee surveys for commuting. A flight to a conference is Category 6; the daily drive to the office is Category 7.
Radiative forcing is the additional warming from aviation’s non-CO₂ effects at altitude — contrails, water vapour, and nitrogen oxides — over and above the CO₂ from burning jet fuel. The GHG Protocol and DEFRA recommend including it for business-travel flights, and DEFRA publishes each aviation factor both with and without the uplift. On the long-haul average it adds roughly 70%. Report flights with radiative forcing included, and state the basis so figures remain comparable year to year.
Yes — the GHG Protocol recommends including the emissions of overnight accommodation within Category 6, and most companies do. Hotel emissions are measured per room-night and vary widely by country, driven by the local electricity grid, climate, and hotel type. A room-night in a hot country reliant on air-conditioning and a fossil-heavy grid can carry several times the footprint of one in a temperate, low-carbon market. The hotel-stay calculator applies country- and class-specific factors.
Use the most specific data available. The fuel-based method allocates actual fuel to the passenger, where an airline or booking tool provides it. The distance-based method — the workhorse — multiplies passenger-kilometres by mode and cabin class by a DEFRA or ICAO factor. The spend-based method applies a sector intensity to travel spend for screening. Most inventories use the distance-based method against travel-booking data, with aviation reported with radiative forcing. The business-travel calculators apply the DEFRA and IATA factors, with the aviation approach in the air methodology.