Calculation Explanations — The Green Offsets Foundation

Principle: Activity × Emission Factor

All Foundation calculators use the fundamental equation: GHG emissions = Activity × Emission Factor. “Activity” refers to the measurable quantity provided by the user (for example: litres of fuel, kilometres travelled, days at sea). The “Emission Factor” is the best-available estimate of how much carbon dioxide equivalent (CO₂e) is released per unit of that activity.

This approach follows the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines for National Greenhouse Gas Inventories, which underpin both national and corporate reporting frameworks such as the Greenhouse Gas Protocol.

Cruise Calculator: Logic and Data Sources

The Cruise Calculator multiplies:

Passengers × [ (Days at Sea × Factor) + (Days in Port × 0.7 × Factor) ]

Port-day emissions are reduced by 30 % to reflect lower propulsion and hoteling loads when docked. The emission factors—ranging from 180 kg CO₂e per passenger-day for small expedition ships to 380 kg for mega-liners—are mid-range values drawn from recent international maritime research.

• International Council on Clean Transportation (ICCT), 2023 – CO₂ emissions from cruise ships in Europe
• Transport & Environment, 2023 – “Luxury on a Grand Scale” report
• International Maritime Organization, 2020 – Fourth IMO GHG Study

These independent analyses all show that cruise travel is among the most carbon-intensive forms of leisure transport—often emitting several hundred kilograms of CO₂e per passenger per day once fuel use, onboard energy, and waste treatment are included.

Uncertainty and Variability

Actual cruise emissions depend on numerous factors: ship size, fuel type (heavy fuel oil, marine gas oil, or LNG), engine age and maintenance, average sailing speed, and whether shore power is used in port. Because of this variability, our calculator provides representative public-education estimates rather than precise audit figures.

Other Calculators (Air, Vehicles, Fuels)

Our other calculators follow the same “activity × factor” structure:

Air travel: uses distance between airports and a per-kilometre emission rate from ICAO Carbon Emissions Calculator.
Vehicles: uses per-kilometre CO₂e rates by vehicle class and fuel type from Natural Resources Canada – Fuel Consumption Ratings.
Fuel use: applies CO₂e per litre or per m³ based on Canada’s National GHG Inventory.

Equivalencies and Comparisons

To give results intuitive meaning, we express them in familiar equivalents—for example, “this cruise produced 12 tonnes CO₂e ≈ driving 77 000 km in a compact car.” That comparison uses an average small-car tailpipe emission factor of 0.155 kg CO₂e per km (155 g/km), consistent with U.S. EPA equivalency data.

Purpose and Transparency

The Green Offsets Foundation’s calculators are designed to help Canadians understand their personal or household greenhouse-gas footprints and see the potential impact of high-efficiency public transit as a mitigation pathway. All methods draw from internationally recognised scientific and governmental sources, updated as new data become available.