Why methodology matters when calculating business travel carbon emissions

Share the love:
Why methodology matters when calculating business travel carbon emissions

By Brigitta Vilmos, Consultant, Sustainable Collaboration

As more and more companies set ambitious sustainability targets to reduce their carbon emissions, having a full and accurate picture of business travel-related emissions is crucial to success.

Business travel often represents a significant portion of a company’s total carbon footprint, and it’s important to choose the right methodology to calculate those emissions. It’s no surprise that different methodologies will result in different emissions figures. For example, if you use a methodology that doesn’t account for aircraft type when measuring air travel emissions, your end result can be significantly higher or lower than the actual figure.

As we begin to see more stringent requirements for reporting on decarbonization strategies in annual reports, there’s an increasing need for reliable and verifiable emissions figures. Methodology matters; let’s dive into why.

What is GATE4?

In 2021, Advito introduced our proprietary Global Analytics for Travel Emissions (GATE4) methodology as a tool for companies tackling carbon emissions from business travel as part of their sustainability strategies. GATE4 is one of the most granular and accurate carbon emissions methodologies that exists today, and the only travel industry-specific tool that is ISO 14064 and ISO 14065 certified. This means the reported emissions figures can be included in annual reports as recognized, robust carbon emissions calculations.

Plus, unlike other methodologies, GATE4 fills the gap and enables businesses to get a full picture of what’s happening in non-traditional categories as well apart from air, hotel, rail and rental car.

Calculating emissions for air travel

For many companies, air travel represents about 90% of their total business travel emissions. However, most don’t account for the wide variety of factors that impact air emissions. They typically use a standardized factor multiplied by the distance, which doesn´t take into consideration the engine efficiency of different aircraft types, or airline and route specificities.

GATE4 considers these seven key factors in calculating air travel emissions:

  • Aircraft type: Significant differences exist in emissions between different aircraft types. Just like cars, each aircraft type varies in per km fuel consumption and this figure can vary based on the distance of the flight. Plus, it’s important to keep in mind, new generation aircraft types are always more fuel efficient than older aircraft types.
  • Cabin class: Business class seats are heavier and take up more space than those in economy, which means business class passengers account for higher share of the total emissions.
  • Cabin configuration: The same aircraft type can use different cabin configurations across different airlines. There are sometimes even several different configurations on the same airline. This will affect the per passenger emissions figures.
  • Airline load factor: This metric shows what percentage of the available seats are filled with passengers. The higher this figure is, the lower the per-passenger emissions are. This metric differs between airlines, and between markets.
  • Pax-to-freight ratio: Most aircraft carry both passengers and cargo, therefore emissions need to be allocated accordingly. This figure shows the share of emissions allocated to the passengers and their luggage, and the share allocated to freight transport.
  • Great circle distance plus distance adjustment: Aircraft are not flying in a straight line from point A to point B, so adjustments for distance have to be taken into consideration. This adjustment accounts for air traffic conditions, weather situations, airspace closures and holding before landing. Other methodologies rely on much less sophisticated distance figures.
  • Radiative forcing factor: This metric accounts for the non-CO2 effects of aviation on global warming (like different exhaust gases and aerosol particles). This is only taken into consideration when cruising at a higher altitude.

Calculating emissions for rail travel

While rail travel accounts for just 1% of emissions from business travel, it can play a crucial role in your decarbonization strategy. Rail, especially high-speed rail networks represent an excellent opportunity to shift some travel away from air, especially in Europe, China, Japan and the Northeast Corridor of the US.

Compared to air, rail emissions on the same route can easily be 50 to 100 times less. Most high-speed rails are fully electrified, and specifically in Western Europe this electricity is often sourced from non-fossil fuels (renewables and nuclear).

In calculating rail emissions, GATE4 considers four key factors:

  • Carbon intensity for electrified railways: This shows how “green” the electricity used is. This figure varies depending on the electricity source, whether it´s based on fossil fuels (such as in China or in India) or non-fossil fuels – nuclear and renewables (such as in France, Switzerland or Sweden). Taking the train in China will emit more CO2 than taking it in France, but will still be significantly more efficient than making the same journey by air.
  • Renewable sourcing initiatives by operators: Some railway operators purchase renewable electricity via direct power purchase agreements or produce their own renewable electricity. In this case, GATE4 takes the operator´s own electricity source into consideration, instead of using the country´s generic carbon intensity figure.
  • Distance: The distance of the train journey. This figure is always different than the same route for air.
  • Load factor: This metric shows what percentage of the available seats are filled with passengers. The higher this figure is the lower the per-passenger emissions are.

Calculating emissions for hotel stays

Hotel emissions represent around 3-4% of the total business travel emissions. However, calculating accurate emissions figures for hotels, and recognizing their efforts towards sustainability is just as important. GATE4 emissions calculations for hotel emissions are based on five components:

  • Geographical location: Energy consumption, and therefore emissions, can vary among hotels within the same category depending on where they are located. For example, a 5-star hotel in Europe will have lower energy consumption than a 5-star hotel in the Middle East. This is because a 5-star hotel in the Middle East is often more luxurious, with additional amenities such as more restaurants and swimming pools.
  • Carbon intensity: As mentioned earlier, carbon intensity shows how “green” the electricity is in a certain country/state. Note that in the US and Canada, carbon intensity differs on a state level.
  • Market tier: Market tier or hotel category can significantly influence energy consumption, increasing the carbon emissions of a property. A 3-star hotel will use significantly less energy and emit less carbon dioxide than a 5-star hotel in the same location. Remember: the emissions figures for properties within the same category can also significantly differ from region to region.
  • Amenities: Certain amenities significantly influence the energy consumption of a hotel. Because of this, GATE4 additionally accounts for the most energy intense amenities, such as swimming pools, spas and restaurants.
  • Green initiatives and local certifications: Eco-certifications are another important aspect of the GATE4 calculation. GATE4 only takes into consideration those that meet the robust criteria of the GSTC accreditation, having passed an on-site audit and developed clear energy targets. Properties with LEED certification, or properties without a green certification but very strong on-site initiatives are taken into consideration as well, such as generating renewable energy, having a strong waste management system in place, or having a program that reduces energy usage and protects the local environment.

Calculating emissions for rental cars

Rental cars represent around 1-2% of the total business travel related emissions. For petrol and diesel vehicles, Advito considers the UK based Department for Environment, Food and Rual Affairs, more commonly known as Defra, emissions factors strong enough, while for hybrid and electric vehicles, we have developed our own calculation methodology.

In calculating rental car emissions, GATE4 considers four key factors:

  • Rental car category (size): Car size can play a large factor in emissions. There is a significant difference in fuel consumption, and therefore emissions, between driving a compact car or driving a large SUV.
  • Fuel: Is the car running on petrol, or on diesel, or is it hybrid or battery electric?
  • Carbon intensity: For the emissions of plug-in hybrid and battery electric vehicles, we evaluate the electricity source (whether it is based on fossil fuels or non-fossil fuel) as this can make a substantial difference in overall emissions.
  • Distance: The distance driven significantly influences the final emissions figures for each car rental.

Going beyond traditional categories

One of the additional advantages of GATE4 is the unique ability to track emissions as well for the non-traditional categories of a business trip, such as personal car usage for business travel, taxi and rideshare usage, and emissions from meals while traveling. In this case, the emissions calculations are based on expense figures.

For personal car and taxi/rideshare calculations, we take the distance driven, vehicle category and fuel type into consideration. When these variables are not available, we use averages based on the clients’ benchmark.

For meal calculations, we consider the type of meals consumed (there is a significant difference in terms of emissions between vegetarian meals and steaks). If this information is not available, we use averages based on the clients’ benchmark, relative to the country where the meal is consumed and where the traveler is from.

As you can see, there are numerous factors to consider in order to get an accurate snapshot of your emissions. Using inaccurate emissions figures in your travel program will lead to bad decision-making by your travelers. With this data at your fingertips, you can develop traveler-facing communications to keep your travelers engaged in achieving your goals, whether that’s by using merchandising strategies to shift share to more sustainable suppliers or educating travelers on policy changes. To learn more about how GATE4 could work for your organization, contact us.

Join 3000+ Subscribers and Receive Advito Insights in Your Inbox.


From stakeholder buy-in to stakeholder inclusion: how to increase adoption of ESG initiatives
If you’re managing a travel program today, you’re likely familiar with the recurring challenge of obtaining senior buy-in for new initiatives. In this article, we’ll...
Advito Partners with eco.mio to Bring GATE4 Emissions Methodology into Multiple Online Booking Tools
Advito, a leading global travel consultancy, and eco.mio, an innovative leader in corporate travel sustainability solutions, have announced their partnership to integrate Advito’s emissions data...