Scope 3 category 6: measuring the CO2 of meeting travel
Scope 3 category 6 covers business travel. How to measure the CO2 of meetings, which data you need, and how to cut it before anyone books.
By Convien teamPublished 7 min read
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Scope 3 category 6 of the GHG Protocol covers the emissions from business travel in vehicles your company does not own: flights, trains, buses, rental cars and private cars used for work trips. For meetings and events, most of these emissions are decided by one choice, the place where people meet. You measure the CO2 of meeting travel from where each attendee starts, how they travel and how far, and the best moment to reduce it is before anyone books a ticket.
This guide explains what category 6 includes, which data you need, how the distance-based and spend-based methods differ, how to treat the extra warming effect of flights, and how we calculate meeting travel emissions in the Meeting Place Finder.
Start with the saving, then the report
Most carbon accounting looks backwards: the trips happened, the invoices arrived, someone turns them into tonnes of CO2. Meeting travel is different, because the important facts are known weeks in advance. You know who is invited, where they are based and when the meeting should take place. That means you can compare candidate locations before the budget is spent.
When the location is chosen with data, travel emissions and travel cost fall together. With the Meeting Place Finder, companies plan meetings with up to 42% less CO2 and up to 35% lower travel cost. In our case study with a DAX-listed company, 219 meetings with 5,652 participants avoided about 1,170 t CO2 and saved over EUR 1M in travel spend. Divided by participants, that is an estimate of about 0.207 t CO2 and about EUR 188 saved per person.
The same calculation that finds the better location also produces the numbers for your Scope 3 report. Saving first, reporting second, from one data set.
What Scope 3 category 6 covers
The GHG Protocol's Technical Guidance for Calculating Scope 3 Emissions (opens in a new tab) defines category 6 as emissions "from the transportation of employees for business-related activities in vehicles owned or operated by third parties, such as aircraft, trains, buses, and passenger cars." It sits within the Corporate Value Chain (Scope 3) Standard (opens in a new tab). Business travel emissions can come from:
Air travel
Rail travel
Bus travel
Car travel, for example rental cars or employees' own cars used for business trips (not commuting)
Other modes of travel
Some travel belongs elsewhere. Vehicles your company owns or controls are reported in scope 1 (fuel) or scope 2 (electricity for electric vehicles). Travel between home and the office is category 7, employee commuting. Leased vehicles your company operates that are not already in scope 1 or 2 fall under category 8. Hotel stays are optional: the guidance says companies "may optionally include emissions from business travelers staying in hotels."
Category 6 is about your own employees. If a meeting brings in customers, partners or external speakers, decide how you treat their travel, state it in your methodology and report it as a separate figure so the boundary stays clear.
The data you need to measure the CO2 of meetings
For the distance-based method, the GHG Protocol asks for the total distance travelled by each mode of transport and, where possible, the countries of travel and the vehicle types. For a single meeting, that translates into a short list:
Origins with head counts: how many people start from which city, postcode or airport. Names are not needed.
The meeting location and date: both change routes, connections and availability.
Mode per journey: flight, train, bus or car, including connections, because a stopover adds distance and take-offs.
Travel class: many emission methods allocate more emissions to larger seats.
Hotel nights (optional): if you include them, count them consistently.
The guidance lists typical sources: data from your travel agency or travel providers, expense and reimbursement systems, and employee surveys. If you cannot collect data for every trip, it allows extrapolation from a representative sample. For planning a meeting, the origins alone are enough to calculate realistic journeys for every candidate location.
Distance-based vs spend-based method
The GHG Protocol names three methods for business travel:
Fuel-based: the fuel actually consumed by the transport provider, multiplied by its emission factor. Precise, but passengers rarely get this data.
Distance-based: distance and mode of each trip, multiplied by an emission factor per kilometre or passenger kilometre.
Spend-based: money spent per mode of transport, multiplied by average emission factors per unit of currency (environmentally extended input-output factors).
The spend-based method is fast when all you have is accounting data. Its weakness is that price is not physics. A flight booked early and the same flight booked at the last minute cause the same emissions, but the spend-based method shows very different values. For meeting decisions, that can point you in the wrong direction: a cheaper ticket might look like lower emissions, even when it means a longer route.
The distance-based method reflects the journey itself. It responds to the things you can actually change, such as the location, the mode and the routing, and it lets you compare candidate cities on equal terms. Use it for meetings and events wherever origins are known, and keep the spend-based method as a documented fallback for the rest of your travel.
Radiative forcing: the extra warming from flights
Aircraft cause warming beyond their CO2. At cruising altitude, contrails and other emissions add effects that are not captured by a CO2 figure alone. This is called radiative forcing. The GHG Protocol leaves the treatment to the company but asks for transparency:
"For air travel emission factors, multipliers or other corrections to account for radiative forcing may be applied to the GWP of emissions arising from aircraft transport. If applied, companies should disclose the specific factor used."
The topic is gaining weight in regulation too. According to the European Commission (opens in a new tab), airlines have had to monitor non-CO2 effects of their flights since 1 January 2025. For your report, choose one approach, apply it in every year and say clearly which one you used.
How Convien calculates meeting travel CO2
The Meeting Place Finder starts from the origins and head counts and calculates the journeys to every candidate city. For flights we use real schedules and fares from global booking systems. Rail, bus and car journeys come from routing services. Your travel policy, travel classes and negotiated rates are applied, and travel time is counted door to door.
For CO2, we use atmosfair data since the end of 2020, following the VDR standard of the German business travel association, and aligned with the GHG Protocol, Scope 3 category 6. The additional warming effect of flights at altitude is shown, so you can see both views. Each candidate city is ranked by travel cost, CO2 and travel time, and you can compare up to three dates. If you already have a preferred location, the cost and CO2 calculator, included at no extra cost, shows how it compares with the optimal place.
The reports are built for two audiences: a savings report for purchasing, with the chosen location against the benchmark, and CO2 figures per meeting for your sustainability team's Scope 3 reporting, exported as PDF or CSV. You can read the full approach in how it works or see the Meeting Place Finder.
Reporting tips for business travel emissions from meetings
Fix the boundary first: employees only, or external attendees as well, and hotels yes or no. Write it down.
Keep one method across years: if you switch from spend-based to distance-based, recalculate the base year or explain the break.
Disclose your radiative forcing approach: with or without, and the factor if you apply one.
Separate planned and actual: the planning estimate guides the decision, the booked data goes into the inventory. Reconcile the two after the meeting.
Report avoided CO2 separately: the comparison with a benchmark location explains a decision. Your inventory shows what was actually emitted, and that number is already lower.
Protect privacy: origins and head counts are enough. Nobody's name needs to be in a travel emissions file.
If your company has climate targets, these numbers feed straight into them. We explain the link in SBTi targets and meeting travel, and what the new carbon price on road fuels means in ETS2 and business travel. Unfamiliar terms are explained in our glossary.
FAQ
Does Scope 3 category 6 include hotel stays?
Optionally. The GHG Protocol allows companies to include hotel nights in category 6 but does not require it. Whatever you decide, apply it consistently and disclose it.
Is the travel of customers and guests part of category 6?
Category 6 covers the travel of your own employees. For external attendees, define your own rule, document it in your methodology and report their travel as a separate figure.
Which is better for meetings, distance-based or spend-based?
The distance-based method. It reflects the actual journey and responds to location, mode and routing. Spend-based figures follow ticket prices, which say little about emissions.
Do I have to include radiative forcing?
The GHG Protocol allows multipliers or other corrections for radiative forcing on flights. If you apply one, disclose the factor. The key is consistency from year to year.
Can I measure the CO2 of a meeting before it is booked?
Yes. With origins and head counts you can calculate the journeys to every candidate location in advance, which is exactly when the CO2 can still be reduced.
You can try this on one of your own meetings: request a free trial (one event with up to 10 attendees, 5 cities, 1 date), or book a demo and we will walk through your next event together.
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