How Atmosfair estimates the CO₂ emissions ?

Calculate the CO₂ emissions of the air traffic is a sensitive and complex task as a lot of factors have to be taken into account which require a sound expertise. That is why we decided to work with Atmosfair which has developed an effective CO₂ calculator so we can display an emissions estimate per flight to help you choose the most carbon efficiency ones.

Atmosfair obtains its data exclusively from independent scientific research projects which have been approved by the German Environment Agency. Under no circumstances does Atmosfair use data provided by the airlines themselves.

The Atmosfair Emissions Calculator takes into account numerous factors that are :

The aircraft type

Modern aircrafts consume less fuel and thus emit less CO₂ than flying old models. The aircraft type can influence positively or negatively the carbon efficiency of an airline. 

Airlines can deploy different aircraft types for each itinerary according to the flying distance, the flight frequency, the passenger potential number etc.

The Atmosfair Emissions Calculator accounts for 121 different aircraft types attaining 97% coverage of the market.

The engine type

The engine type associated with an aircraft has also an influence on the CO₂ and the non-carbon emissions. The less fuel the engine consumes, the lower the emissions will be.

The Emissions Calculator accounts for 408 different engines in total and therefore attains a market coverage of 96%.

The distance and stopovers

The fuel consumption of an aircraft strongly depends on the total flight distance. The longer the flight, the higher the overall consumption. Moreover, long-haul flights consume more fuel because it has to be transported for most of the flight and will only be fully consumed at the very end. This increases the aircraft weight during the longest part of the flight and thus the CO₂ emissions.  

Travelling close to home and less often on long-haul flights seems to be more appropriate.

The phases

To get an accurate output, the Atmosfair Emissions Calculator takes into account the fuel consumption related to each flight phase.

It differentiates the  take-off phase, the climb phase during which the aircraft climbs to cruising altitude, the cruise phase, the descent phase before landing and the landing phase. The CO₂ emissions released will depend on the flight phase. 

Thus, the take-off and landing phases have a comparatively high CO₂ emissions release. For these reason, the carbon footprint¹ of non-direct flights is higher than directs which have to be preferred in order to limit the environmental impact. 

Detours

Flying between two cities consist in connecting point A to point B, but in reality there are always detours to reach a destination. Studies have shown that detours range to approx. 50 kilometers for any distance so the calculator applies this value automatically to all flights.

The flight class

Business and first seats use up more space and are heavier which increase the aircraft total weight. Travelling in premium classes is CO₂-guzzler than in economy class.

Thus, an economy passenger consumes 20% less fuel on average than the other classes. On the other hand, a business passenger requires 50% more fuel on average and a passenger in first class uses twice as much. This factor is also taken into account into the calculator.

Ground operations

Taxiing and landing require manoeuvres from the terminal to the runway using some vehicles. A study on fuel consumption during taxiing showed that approximately 2.5 kilograms of kerosene ³  are necessary per passenger which is apply as a flat rate for all other flights.

The passenger load

The passenger occupancy rate is the relation between occupied seats during a flight compared to the seats left empty. This rate is a key factor in determining the load capacity and the fuel consumption. The more the aircraft is full, the less the CO₂ emissions per passenger are important.

The Atmosfair Emissions Calculator includes the Passenger Load Factor of the individual airlines in its calculations.

The cargo load factor

Passengers and goods are transported during commercial flights (the term air freight is used when it comes to transporting merchandises). The amount of additional cargo depends on different factors like passenger occupancy rate and the amount of kerosene ³ needed to reach the destination. The more goods weight the aircraft down, the more CO₂ emissions important. 

Therefore, the Atmosfair Emissions Calculator takes into account not only the passenger load factor but also the cargo load factor of the respective airline.

The intermediate result is the amount of CO2 per passenger on a specific flight route, flown by a particular aircraft belonging to a particular airline to which are the non-carbon emissions added to the calculator first output.

The non-carbon emissions

The combustion of kerosene ³ produces CO₂ and non-carbon emissions that contribute directly or indirectly to raising global temperatures. The Emissions Calculator only processes the non-carbon emissions when the flight profile exceeds 9000m altitude (these emissions impact the atmosphere from this altitude only).

What are the non-carbon emissions ?

• Nitrogen oxides : the nitrogen oxide is a gas released during the kerosene³ combustion. When the air is overloaded in gas, this can lead to the damage of the ozone layer and thus contribute to the global warming. 

• Condensation trails and ice clouds : these contrails can only be formed if the air through which the aircraft flies is cold enough and the aircraft is at a high altitude. These trails disrupt the atmosphere balance and participate in the global warming.

The non-carbon emissions are added to the intermediate result and the final output unit is CO₂ equivalent (CO₂e) as non-carbon emissions have been introduced.

¹ Carbon footprint : the carbon footprint helps to measure the environmental impact of an activity and more specifically the greenhouse gases induced by this activity. 

²  Airline carbon efficiency : the carbon efficiency of an airline depends on its capacity to limit its CO₂ emissions. The more the airline limits its emissions, the highest its efficiency will be. To achieve this, an airline has several leverages such as the purchase of modern aircrafts, the reduction of wastes on board, the use of biofuels* etc.

³  the kerosene is the fuel made from oil and used by aircrafts because of its properties. 

* Biofuels : biofuels are made from renewable organic materials (raw material of plant or animal origin or from wastes). For instance, they can be produced from waste cooking oils. Thus, biofuels are less CO₂ emitting than kerosene as the emitted CO₂ during their use is offset by the CO₂ absorbed during the plant growth. Nevertheless, this effect will depend on the biofuels production method (if the method requires CO₂ emitting resources, this effect might be diminished).