Air Travel


Globally, air travel accounts for around 2% of all greenhouse gas emissions (GHG). As the world becomes more connected and mobile, this is also one of the fastest rising sources of emissions, which can lead to significant challenges for meeting global climate goals. 

Across higher education, many universities are beginning to reflect on the climate impacts of increasing international collaborations, recruitment, research, and other travel activities from both employees and students. These are often incredibly important activities to conduct, generating significant value for research, education, and partnership purposes, but they do come at an emissions cost. 

As part of Waterloo’s climate action plan, Shift:Neutral, the University committed to explore tools and guidelines that would reduce business travel where possible, and would improve tracking. 

Emissions calculator

To engage the UWaterloo community directly in the effort of tracking and reducing emissions, we’ve added a new voluntary field in Concur ”carbon emissions” that asks Claimants who have booked and purchased their airfare out of pocket to voluntarily calculate and include the greenhouse gas emissions associated with their UW travel. 

This calculator takes less than 30 seconds for most simple trips, and for longer complicated trips with many layovers/stops, may take a minute or two at most. Completion of the carbon emissions field in Concur is voluntary, however, we strongly encourage all Claimants to take a few extra seconds to fill this out and help campus better understand the GHG impact from our air travel. 

To complete this field, Claimants should use the emissions calculator developed by the International Civil Aviation Organization (ICAO). You will need to input into the calculator the following information: 

  • Your departure city 

  • Your destination city 

  • Additional destination cities if it was not a direct flight 

  • The number of passengers 

  • What class of flight you took (i.e. Economy/Premium) 

  • Whether it was a round trip 

The calculator will provide a number of data points, giving you information about the flight. The only data point you need to enter into Concur is the field “Total passengers’ CO2/journey”, as shown below for an example trip from Toronto Pearson to London Heathrow: 

Screen shot of the Carbon Emissions Calculator indicating that a flight from YYZ to LHR is 617.80 CO2/journey (KG)

NOTE:  No calculation is needed for travel booked through Frederick Travel or FCM. Both FCM and Frederick Travel provide information to the University directly to calculate the impact of a flight. 

Calculator Steps & Details

1. Go to the ICAO carbon emissions calculator website

ICAO Carbon Emissions Calculator


2. Select “Passenger Calculator"

Arrow pointing to the "Passenger Calculator" button


3. Add your departure and destination cities by typing the city name into the prompt area and selecting the accurate airport. For example, typing “Toronto” will bring up Toronto-Pearson and Toronto-Billy Bishop Airports.

"Toronto" is typed into the "Departure" field of the calculator and a dropdown expands, listing airports in Toronto


4. If you have multiple flights and/or layovers, click “Add Destination” to add a new line. You may add up to two (2) additional destinations/”legs” of your trip as are needed, in the order in which you travelled.

Arrow pointing to the button titled "Add Destination" on the calculator


5. Enter the number of passengers, cabin class, and whether it was a round-trip or one-way trip, and click “Calculate”

Image of the section of the calculator with the "Number of Passengers", "Economy", and "Round Trip" circled


6. Copy the "Aircraft Fuel Burn/journey (kg)" value and paste it into the "Carbon Emissions (kg)" field on Concur.

Screen shot of the Carbon Emissions Calculator indicating that a flight from YYZ to LHR is 617.80 CO2/journey (KG)


Important notes:

  • Only enter the emissions for the flight for which you are submitting the claim. The number of people that you add to the flight should match the number of people on the invoice/receipt you are claiming.
  • If you have multiple flight receipts/purchases, calculate the emissions for each separately.
  • Make sure to add destinations in the order in which you travelled. For example, if you travelled from Toronto to Rome but had a transfer in Frankfurt, enter Toronto >> Frankfurt >> Rome and not Toronto >> Rome >> Frankfurt.
  • If your return trip was through a different route, enter each airport code separately and select “One Way” in Step 4.
    • For example, if you traveled from Toronto to Paris, then flew from Paris to Rome, and took a return flight from Rome directly to Toronto, enter Toronto >> Paris >> Rome >> Toronto as a one-way trip.

Reducing emissions

As part of Waterloo’s long-term carbon reduction journey, it will be increasingly important to take efforts that reduce emissions from all sources, including air travel. At the same time, it is recognized that there is clearly a need and value for employee and student air travel that will remain for the foreseeable future. This page will be updated over time with resources and guidance on strategies that can reduce emissions from air travel.  

  • Reducing number of trips – i.e. ones most valuable for relationship building, networking, etc. 

  • Reducing number of participants 

  • Supporting virtual delegations

  • Chaining trips together & avoiding short trips 

  • Flying economy (per UW guidelines)

  • Searching out airlines that are more efficient or use low-carbon fuels 

Calculator FAQs

Below are frequently asked questions about this initiative.

Why are we collecting air travel emissions information?

The primary purpose for collecting the data is to gain a better understanding of emissions generated from air travel. It is also meant to engage members of the campus community to better understand the emissions impact of their travel. The Sustainability Office and other departments continue to monitor best practices for options to reduce emissions from air travel, but submission of this information right now does not create any other requirements for individuals or departments. 

Do I have to do submit emissions data?

Completion of the field is voluntary. However, the information is highly important to assist the University in accurately understanding the emissions from air travel. If a Claimant does not wish to fill out the field, they are not required.

Who has access to my emissions information?

All information submitted through Concur remains confidential with Finance per current University processes. The Sustainability Office works with Finance to receive an anonymized report, scrubbed of all identifying information, to assist in the calculation of air travel emissions. There remains, at this time, no evaluation of emissions by department/faculty/org unit etc. Fully aggregated information will be published as part of the University’s annual sustainability report in 2024 and beyond.

Can I use a different emissions calculator?

Only the ICAO calculator should be used. There are several different calculators available that function very similarly, and some travel booking or search websites such as Google may also include information about GHG emissions. However, they may use different methodologies and have a more complicated user experience. For consistency and reliability, the Sustainability Office asks the campus to use the ICAO calculator at this time.

Should I purchase carbon offsets?

The ICAO indicates that the calculator can be used to estimate emissions that can be balanced with the purchase of carbon offsets. At this time, it is not recommended to purchase third-party carbon offsets with University funds. There are challenges with the credibility of offset marketplaces and currently no process for tracking the purchase of offsets so they can be integrated into Waterloo’s emissions reporting system. Additional guidance will be developed in the future for ways in which travellers can reduce their emissions through an offset mechanism or equivalent.

My destination is not appearing in the list of options, what should I do?

The ICAO calculator uses real-time flight routes/schedules from airports across the world to verify routing. If your destination does not appear, it is likely because you took a transfer or there was not a direct flight. Make sure to add any waypoints. If the flight routes/locations are accurate, it may have been a special flight or a chartered flight that is not on normal airport routes. The best option is to input the most logical route to a similar city or nearby airport, or leave the field blank.

Should I report for more than one person?

The number of people that you add to the flight should match the number of people on the invoice/receipt you are claiming. If each traveller paid their own flight, they would each submit their own individual claim per usual University processes, and add their own individual emissions. If a single Claimant paid for multiple persons, then the appropriate number of people can be selected in Step 5.

I am submitting multiple flight claims – can I lump them together in one GHG emissions number?

The emissions calculation should match the receipt that is being claimed and should not be lumped together with information from other purchases. For example, if you paid for a one-way flight to a city, and paid separately for a return flight, record the one-way emissions under each flight when claiming each expense.

I paid for my flight through a travel agent or through FCM, do I need to indicate GHG emissions information anywhere?

No. Both FCM and Frederick Travel provide information to the University directly to calculate the impact of a flight. No user input is needed when booking flights through these tools. Airfare purchased out of pocket and submitted via Concur currently does not collect the information that is typically needed to run an emissions calculation (i.e. the departure, destination, one-way/two-way flight details you add to the ICAO calculator). However, members of the University are welcome and encouraged to use the calculator before/after their flight to better understand the impacts of that travel!

I have more than three destinations, what should I do?

The ICAO calculator currently only accepts up to 3 destinations/legs of a journey. If you have a long/complex trips with many stops, the easiest thing to do is to complete the calculator in sequential order and add the totals from the ICAO into a single line-item when submitting. If some of those flights are paid on separate receipts, complete them individually along with each claimed expense.

How does the ICAO calculate the GHG emissions associated with a flight?

On the landing page of the ICAO calculator, there is a link to the methodology of the calculator. It calculates the distance travelled, pulls typical aircraft that fly the indicated routes, the fuel efficiency of the aircraft, passenger/freight loading factors (how full/heavy the plane is), and other details available through the ICAO to calculate the amount of per-passenger fuel burned to take the flight.

Does the ICAO include a radiative forcing multiplier in the calculator?

At this time, no. Radiative forcing is a measure of how much of a warming effect that various greenhouse gas emissions have, typically normalized to carbon dioxide emissions (CO2). The calculator provides only the real CO2 output. However, CO2 released higher in the atmosphere has a stronger warming effect than the same amount of CO2 released at/near ground level. In practice, this usually means that the warming effect of air travel emissions is roughly double the warming effect of the same amount of CO2 released at ground level. There does, however, remain some debate on how best to calculate this. The Sustainability Office will apply a separate multiplier to more accurately address this. Users should only submit the number shown in the output of the ICAO calculator.

Why do flights of different lengths have disproportionate emissions?

You may notice, as you are submitting, that the emissions from flights do not always have a linear correlation with the length of the flight. This is because the largest portion of fuel spent in a flight comes from takeoff and landing. As such, short-distance flights will tend to have lower emissions overall, but larger per-kilometer emissions, compared to a long-distance flight. This is also why a direct flight to a destination would have lower overall emissions compared to an indirect flight with a transfer.

Why are emissions higher for premium seats?

Premium seats take up more room on a plane; therefore, they contribute more to the total emissions of a journey.