The distance-based method for Scope 3 category 6, flight by cabin class, rail, car and hotel nights, and the method choices that can move the total by as much as half.
Business travel emissions, Scope 3 category 6, are passenger-kilometres by mode and cabin class, with flight distances uplifted for indirect routing, multiplied by an emission factor per passenger-km, plus a factor per hotel night. For an illustrative company of 850 employees the total is 704.7 tCO2e, 0.83 per employee, including radiative forcing on flights. Without radiative forcing it is 467.2, and 60 business-class long-haul flights alone are a quarter of the total.
Worked in full in The ESG Manager in Private Equity by Julian R. Sterling, with every figure reproduced in a free workbook.See the book on Amazon →
The travel data comes from the company's travel agency, one line per one-way flight segment, with great-circle distance and cabin class. The emission factors below are illustrative and rounded, of the kind published each year in government conversion factor tables; use the current year's table and cite it.
| Mode | Segments | Distance, km | Factor, no RF | Factor, with RF |
|---|---|---|---|---|
| Domestic flights | 400 | 450 | 0.14 | 0.24 |
| Short-haul, economy | 900 | 1,100 | 0.10 | 0.17 |
| Long-haul, economy | 160 | 6,500 | 0.08 | 0.14 |
| Long-haul, business | 60 | 6,500 | 0.24 | 0.42 |
| Rail, passenger-km | 650,000 | 0.035 | 0.035 | |
| Car, km driven | 420,000 | 0.17 | 0.17 | |
| Hotel nights, kg a night | 3,200 | 15.0 | 15.0 |
Flight distances get an 8 per cent uplift for indirect routing, holding patterns and diversions, a common convention. The illustrative factors here exclude it; some published tables, including the UK government's, build it into their flight factors and expect great-circle distances, in which case it must not be added again. RF is radiative forcing: the extra warming from non-CO2 effects of aviation at altitude.
Passenger-km = segments × great-circle km × 1.08
Long-haul business: 60 × 6,500 × 1.08 = 421,200
Emissions, tCO2e = passenger-km × factor / 1,000 = 421,200 × 0.42 / 1,000 = 176.9
Excel: =Segments*Km*(1+Uplift)*Factor/1000
Count segments, not trips. A return trip to New York is two segments of the same length; a booking with a connection is two or three segments of different lengths, each with its own haul band.
| Mode | Passenger-km | No RF | With RF | Share of total |
|---|---|---|---|---|
| Domestic flights | 194,400 | 27.2 | 46.7 | 6.6% |
| Short-haul, economy | 1,069,200 | 106.9 | 181.8 | 25.8% |
| Long-haul, economy | 1,123,200 | 89.9 | 157.2 | 22.3% |
| Long-haul, business | 421,200 | 101.1 | 176.9 | 25.1% |
| Rail | 650,000 | 22.8 | 22.8 | |
| Car | 420,000 | 71.4 | 71.4 | |
| Hotel nights | 48.0 | 48.0 | ||
| Total | 467.2 | 704.7 |
Flights are 562.6 of the 704.7 tonnes. Within them, business class is the line to watch: 60 segments are 3.9 per cent of the flights booked and 25.1 per cent of the company's travel emissions, because a business seat carries 3.0 times the economy factor on the same aircraft.
| Choice | Total | Change |
|---|---|---|
| Distance-based, with RF, by class, 8% uplift | 704.7 | 0.0 |
| Without radiative forcing | 467.2 | -237.5 |
| No cabin class: all long-haul at the economy factor | 586.8 | -117.9 |
| Return trips recorded as one long-haul segment | 537.6 | -167.1 |
| No distance uplift | 663.0 | -41.7 |
| Spend-based, 2.1 million at an illustrative 0.25 kg per euro | 525.0 | -179.7 |
Radiative forcing is the largest choice, 50.8 per cent on top of the CO2-only figure. Disclose which you used, and do not switch between years: a reduction made of a change in method is not a reduction.
Three sources cover most of it. The travel agency or booking tool holds flights and rail with origin, destination and class; ask for a segment-level export rather than a summary. Expense claims hold mileage driven in employees' own cars, the 420,000 km here, and taxis. The hotel booking tool or expense data holds nights, 3,200 here, about 3.8 per employee. Ground travel and hotels together are 142.2 tonnes, a fifth of the total, so they are worth collecting but rarely worth refining. Car mileage is the one to check: at 71.4 tonnes, 10.1 per cent of the total, it is larger than domestic flying, and it is the line most often left out because it sits in payroll expenses rather than in the travel agency's report.
Where a booking lacks distance, compute it from the airport pair with a great-circle calculator, then apply the uplift. Do not apply the uplift twice: some agency reports already include it.
Using one average flight factor. Travel agency exports often carry distance but not class, and the tempting fix is a single factor per haul. On this company it removes 117.9 tonnes, 16.7 per cent of the total, and it hides the most effective lever the company has: moving the 60 long-haul business segments to economy saves the same 117.9 tonnes, while moving every domestic flight to rail saves 39.9, 5.7 per cent. Ask the agency for class; it is in the booking.
For a portfolio, the same discipline applies across companies: one factor table, one RF choice and one uplift for every company, so that the fund's figure is a sum of like with like.
When only spend is available, the method and its pitfalls are in how to calculate Scope 3 emissions with the spend-based method. The working documents and blank model that go with the book are in the free files for this book.
The GHG Protocol leaves it optional, but many reporters include it for flights, because non-CO2 effects at altitude add materially to warming, and the UK government recommends its factors with RF. Disclose the choice. It is the largest single choice in the calculation: in the illustrative case radiative forcing takes the total from 467.2 to 704.7 tCO2e, 50.8 per cent more. Whichever you choose, apply it consistently across years.
Emissions are allocated by the floor space a seat takes, so a business-class seat carries about 3.0 times the economy factor on the same flight. In the illustrative case, valuing all long-haul flights at the economy factor understates the total by 117.9 tCO2e.
Yes, where the travel agency can provide routes and classes, because it reflects what was flown rather than what was paid. On the illustrative company an illustrative spend-based factor gives 525.0 tCO2e, 25.5 per cent below the 704.7 of the distance-based total; fares and emissions do not move together.
This article is one calculation from The ESG Manager in Private Equity. The book takes the same case from first principles to the decision, chapter by chapter, and every figure it prints is a live formula in the free companion workbooks.
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