Business events can create emissions before the first session begins. The largest measured share often comes from attendee flights, while ground transport and hotel rooms add distinct sources that planners can estimate separately. The figures below provide 2026 UK conversion factors, hotel benchmarks based on 2021 data, and reported footprints from COP27 and COP28.
Contents
- How to read the factors
- Air travel and non-CO2 effects
- Flight class and direct greenhouse-gas factors
- Cars and motorcycles
- Public transport, taxis, and rail
- Hotel nights by country
- What major conferences measured
How to read the factors
Most transport figures in the 2026 UK Government business-travel factor set are expressed as kilograms of carbon dioxide equivalent (kg CO2e) per passenger-kilometre or vehicle-kilometre. Passenger-kilometre figures describe one passenger travelling one kilometre; vehicle-kilometre figures describe the vehicle’s travel. A hotel figure is assigned per room night.
The air-travel factors in the first group include indirect non-CO2 effects. The same factor set applies a 70% increase to the CO2 factor for effects such as contrails, water vapour, and nitrogen oxides. These are conversion factors for estimation, not a measurement of one particular itinerary. The source is the Conversion factors 2026: full set (for all users), covering the 2026 factor set.
For planning, record the route, cabin class, mode, distance, and number of travellers. Keep the geography visible: a UK domestic flight, a flight to or from the UK, and a flight between non-UK destinations are separate categories in the source.
Air travel and non-CO2 effects
The 2026 average domestic flight to or from the UK has a factor of 0.22928 kg CO2e per passenger-km including non-CO2 effects. The comparable average short-haul factor is 0.12786 kg CO2e, while short-haul economy is 0.12576 kg CO2e and short-haul business class is 0.18863 kg CO2e per passenger-km.
For longer journeys to or from the UK, the average long-haul factor is 0.15282 kg CO2e per passenger-km. Long-haul economy is 0.11704 kg CO2e, premium economy is 0.18726 kg CO2e, business class is 0.33940 kg CO2e, and first class is 0.46814 kg CO2e per passenger-km. Those class-specific differences matter when an event policy allows premium cabins for long-distance speakers or staff.
The same 2026 factor set gives separate values for international flights between non-UK destinations. The average is 0.14253 kg CO2e per passenger-km, international economy is 0.10916 kg CO2e, and international business class is 0.31656 kg CO2e. These values should not be silently substituted for UK domestic or UK-origin categories.
For a compact comparison, the supplied factors are:
| Air journey category | Factor including non-CO2 effects |
|---|---|
| UK domestic average | 0.22928 kg CO2e/passenger-km |
| UK short-haul economy | 0.12576 kg CO2e/passenger-km |
| UK short-haul business | 0.18863 kg CO2e/passenger-km |
| UK long-haul economy | 0.11704 kg CO2e/passenger-km |
| UK long-haul business | 0.33940 kg CO2e/passenger-km |
| UK long-haul first | 0.46814 kg CO2e/passenger-km |
| Non-UK international economy | 0.10916 kg CO2e/passenger-km |
| Non-UK international business | 0.31656 kg CO2e/passenger-km |
These numbers are most useful as consistent planning inputs. They do not establish the emissions of every aircraft, airport transfer, or passenger itinerary.
Flight class and direct greenhouse-gas factors
The methodology report separates the direct greenhouse-gas factors from the non-CO2 uplift. Before that uplift, the 2026 average domestic-flight total GHG factor is 125.2 grams CO2e per passenger-km. The average short-haul factor is 69.7 grams, short-haul economy is 68.6 grams, and short-haul first/business is 102.9 grams.
For long-haul travel, the pre-uplift average is 83.2 grams CO2e per passenger-km. Long-haul economy is 63.7 grams, business is 184.9 grams, and first class is 255.0 grams. For an average international flight between non-UK destinations, the pre-uplift factor is 77.8 grams; international economy is 59.6 grams and international business is 172.8 grams.
The direct-factor figures come from the 2026 Government greenhouse gas conversion factors for company reporting: Methodology paper. The report identifies the factor set as 2026 and the underlying aircraft inventory as 2023. That distinction is important when an event report describes these as methodology-based estimates rather than newly measured flights.
Cars and motorcycles
For business-event travel by car, the 2026 UK factors vary by fuel and vehicle type. A diesel mini car is 0.10998 kg CO2e per kilometre, compared with 0.13014 kg for a petrol mini car. A diesel average car is 0.17265 kg, while a petrol average car is 0.16152 kg per kilometre.
At the luxury end, the diesel factor is 0.20205 kg CO2e per kilometre and the petrol factor is 0.30350 kg. These are vehicle-kilometre factors, so planners should keep occupancy assumptions separate rather than treating them automatically as per-person values.
Motorcycle factors range from 0.08319 kg CO2e per kilometre for a small motorcycle to 0.13252 kg for a large motorcycle. The medium motorcycle factor is 0.10108 kg, and the average motorcycle factor is 0.11367 kg per kilometre. All of these figures are from the Conversion factors 2026: full set (for all users).
For an event travel survey, useful fields include vehicle category, fuel, distance, and occupancy. Without occupancy, a vehicle figure cannot be compared directly with a passenger-kilometre figure. That is a measurement boundary, not a missing detail to fill with an assumption.
Public transport, taxis, and rail
The 2026 regular taxi factor is 0.14861 kg CO2e per passenger-km, while a black cab is 0.20402 kg. Bus geography matters: a local bus outside London is 0.12552 kg, London local bus is 0.06360 kg, and the average local-bus factor is 0.10151 kg CO2e per passenger-km.
Coach travel has a factor of 0.03948 kg CO2e per passenger-km. National rail is 0.03092 kg, based on diesel and electric trains in 2024–25. International rail is 0.01135 kg, and the London Underground factor is 0.01549 kg per passenger-km.
| Mode or service | 2026 factor |
|---|---|
| Regular taxi | 0.14861 kg CO2e/passenger-km |
| Black cab | 0.20402 kg CO2e/passenger-km |
| Local bus outside London | 0.12552 kg CO2e/passenger-km |
| London local bus | 0.06360 kg CO2e/passenger-km |
| Coach | 0.03948 kg CO2e/passenger-km |
| National rail | 0.03092 kg CO2e/passenger-km |
| International rail | 0.01135 kg CO2e/passenger-km |
| London Underground | 0.01549 kg CO2e/passenger-km |
The national-rail number has a 2024–25 activity basis even though it appears in the 2026 factor set. Stating both periods prevents the factor’s publication year from being mistaken for the activity year.
Hotel nights by country
Accommodation can be tracked per room night. The 2026 factor set assigns 10.4 kg CO2e to a UK hotel room night and 11.5 kg to a London room night. Its country benchmarks, based on an underlying 2021 benchmark, assign 35.0 kg to an Australian room night, 12.2 kg to a Belgian room night, and 53.5 kg to a Chinese room night.
The French benchmark is 6.7 kg CO2e per room night, while the German benchmark is 13.2 kg. An Indian room night is 58.9 kg, a Japanese room night is 39.0 kg, and a US room night is 16.1 kg.
| Location | Assigned emissions per room night |
|---|---|
| France | 6.7 kg CO2e |
| United Kingdom | 10.4 kg CO2e |
| London | 11.5 kg CO2e |
| Belgium | 12.2 kg CO2e |
| Germany | 13.2 kg CO2e |
| United States | 16.1 kg CO2e |
| Australia | 35.0 kg CO2e |
| Japan | 39.0 kg CO2e |
| China | 53.5 kg CO2e |
| India | 58.9 kg CO2e |
These values are assigned benchmarks, not a direct audit of the hotel selected for an event. The Conversion factors 2026: full set (for all users) identifies the underlying hotel benchmark period as 2021.
What major conferences measured
Conference reports show how travel can dominate a large international event footprint. The COP 28 Sustainability Report reports a baseline assessment of 333,414 tonnes of CO2e across the assessed 2023 event footprint. Air travel represented approximately 71.6% of calculated residual emissions, accommodation represented 16.7%, and local travel represented 2.1%.
The COP28 percentages describe the report’s calculated residual-emissions breakdown; they should not be recast as a universal share for every business conference. They do, however, identify attendee aviation and accommodation as material categories for international-event planning.
The COP27 Sustainability Report reports 44,103.80 tonnes of CO2e from international flights in 2022. Its international-and-local transport table reports 45,395.88 tonnes of CO2e in total. Within local transport, natural-gas buses produced 570.46 tonnes, while the electric-bus fleet produced 533.59 tonnes from 1,163.27 MWh of electricity use.
COP27 also reported approximately 170 tonnes of CO2e in avoided emissions from its electric-bus fleet. Its UN-bus transport produced 172.00 tonnes of CO2e from 26,020 kilometres of travel. These are reported event-specific results, not factors that should be applied to another venue without comparable activity data.
For business event planning, the practical measurement structure is therefore clear: separate flights by route and cabin class, ground travel by mode and geography, rooms by location and nights, and measured event totals by reporting boundary. Keeping the period and source label beside each number makes an estimate auditable without presenting a benchmark as a universal result.