Learn how we calculate your emissions, explore the science behind our numbers, and discover how small nudges at the right moment can shift the way you travel.
GreenRoute's methodology is grounded in recognized scientific and institutional sources. The IPCC defines how greenhouse gas emissions can be estimated by combining activity data with appropriate emission factors. In parallel, the UK Department for Energy Security and Net Zero (DESNZ) publishes standardized conversion factors that make it possible to compare emissions across transport categories in a consistent way.
We combine both references to estimate transport related carbon emissions through a simple but transparent framework: trip distance multiplied by a mode specific emission factor, adjusted for vehicle type, fuel source, and where relevant the number of passengers.
Following the IPCC's distance based indicator approach, GreenRoute uses two main formulas depending on whether the transport is private or collective.
Cars, motorbikes
Bus, train, ferry, plane
For collective modes, the emission factor is already expressed on a per passenger kilometer basis (following DESNZ average occupancy assumptions), so no division by passengers is needed.
Each mode has its own set of emission factors depending on fuel or energy source. The numbers below are what GreenRoute uses to calculate your footprint.
Our emission factors come from two main sources: Framtiden i våre hender (based on Klimatsmart semester, Chalmers 2024) for car, train, plane, and indicative benchmarks, and the European Environment Agency (EEA) for bus, ferry, and motorbike. CH₄ (methane) values from the EEA are also included for completeness but represent less than 0.2% of the total.
Because buses carry multiple passengers simultaneously, emission factors already reflect average occupancy. Bus travel is one of the more efficient motorized options per person.
| Fuel Type | Emission Factor (kg CO₂e / km per passenger) |
|---|---|
| Diesel | 0.10231 |
| Electric / Hydrogen | 0 |
Car emissions depend on distance, vehicle type, and the number of passengers. The per passenger footprint drops dramatically when you carpool. GreenRoute applies the formula CO₂e = d × ef / p for cars, where p is the number of people in the vehicle.
| Vehicle Type | Emission Factor (kg CO₂e / km) |
|---|---|
| Petrol (Gasoline) | 0.171 |
| Diesel | 0.171 |
| Hybrid | 0.110 |
| Electric | 0.050 |
Electricity generation itself carries a carbon cost that varies by country and energy mix. In Norway, where the grid is predominantly hydroelectric, real electric vehicle emissions are lower than the European average. For cross country consistency, GreenRoute applies the DESNZ standard factor.
A solo driver in a petrol car emits 0.171 kg CO₂e / km. Shared among four passengers, that same trip drops to roughly 0.043 kg CO₂e / km per person, comparable to driving an electric car solo.
Aviation is the most carbon intensive mode per kilometer in our model. A single transatlantic flight can outweigh months of ground based emissions.
GreenRoute distinguishes between two cabin classes using average emission factors for scheduled flights. Business class travel emits roughly 2.2 times more per passenger than economy, because premium cabins allocate more space and more fuel per seat.
The factor is already expressed on a per passenger basis (accounting for average occupancy), so you do not enter the number of passengers separately.
| Flight Class | Emission Factor (kg CO₂e / km per passenger) |
|---|---|
| Economy | 0.127 |
| Business Class | 0.284 |
Trains running on low carbon electricity are among the lowest emission motorized options. A train powered by Nordic electricity emits roughly 7 g CO₂e per passenger km, which is almost 15 times less than a bus and nearly 24 times less than a solo car trip.
Like other collective modes, the per passenger emission factor already incorporates average occupancy.
| Energy Source | Emission Factor (kg CO₂e / km per passenger) |
|---|---|
| Electric (Nordic grid) | 0.007 |
Passenger ferries have relatively high per passenger emissions compared to trains or buses. Norway is investing in electric ferries across its fjord routes, which will significantly reduce this figure over time.
| Fuel Type | Emission Factor (kg CO₂e / km per passenger) |
|---|---|
| Diesel | 0.11131 |
| Electric | 0 |
Motorbikes are more fuel efficient than cars due to their lighter weight, but they still emit significantly more per kilometer than public transport options. As a private vehicle, GreenRoute treats motorbike emissions on a per rider basis.
| Fuel Type | Emission Factor (kg CO₂e / km) |
|---|---|
| Petrol | 0.09816 |
| Electric | 0 |
Walking and cycling are assigned an emission factor of 0 kg CO₂e / km. While any human activity technically involves metabolic energy, GreenRoute follows the DESNZ convention of treating these modes as zero emission for transport comparisons. They are the greenest options by a wide margin.
Here is an indicative ranking of greenhouse gas emissions per passenger kilometer across modes. Values are drawn from Framtiden i våre hender (Klimatsmart semester, Chalmers 2024) and represent typical averages. The further down the list, the higher the climate cost.
Values in g CO₂e per passenger kilometer. Source: Framtiden i våre hender / Klimatsmart semester Chalmers (2024). The app's per mode factors may differ slightly from these indicative benchmarks as they draw on additional EEA data for bus, ferry, and motorbike.
Most carbon calculators stop at a result. GreenRoute integrates behavioral design into the core of the application, drawing on nudge theory. The idea is simple: people are more likely to make sustainable choices when the sustainable option feels like the natural one, rather than being imposed by rules.
Behavioral research suggests interventions work best at the exact moment of choice. GreenRoute delivers information precisely when you are about to log a trip.
Rather than "this trip emits 12 kg of CO₂e", GreenRoute translates numbers into tangible comparisons: square meters of Arctic ice, months of tree absorption, equivalent car trips.
You do not just see your own emissions. You see how your choice compares to lower carbon alternatives, making the trade off concrete.
The aim is not guilt, but gentle nudging: making the environmental consequences of everyday transport decisions feel real, personal, and worth acting on.
GreenRoute is transparent about the boundaries of its methodology. Emissions estimation depends on activity data and average factors, which means results are comparative estimates, not exact measurements. Actual emissions vary with:
We present results as robust comparative estimates to support decision making, not as precise life cycle measurements. That transparency is central to the app's credibility.