- CO2 on the way to school

The CO2nnect CO2 calculator works by multiplying the distance travelled to school by a ”multiplier”. The multiplier defines the amount of CO2 emitted per passenger and per kilometer for a given mode of transport.

Each mode of transport (walking, bicycling, car, train, etc.) will have a different multiplier. The multipliers have been pre-programmed into the CO2nnect calculator and the calculations are done automatically for you.

Note that the CO2nnect multipliers:

Here is a list of the CO2 multipliers we have selected to use in CO2nnect
Figures denote kg CO2 per km per passenger:

We have tried to include the most common modes of transport to school across the globe - but we have probably missed some!

Most of the multipliers we use in CO2nnect have been taken from the UK Department of Environment (Defra). The source is “2008 Guidelines to Defra’s GHG Conversion Factors: Methodology Paper for Transport Emission Factors.”

Where this document does not give data on a mode of transport, we have used other sources. CO2nnect has consulted with experts on carbon calculators while selecting the multipliers. They have confirmed that the multipliers are reliable enough for our purposes.

How accurate are the multipliers and the CO2nnect results?
The multipliers in CO2nnect come from very reliable sources, they are based on 2008 data and have been confirmed by carbon calculator experts. We are confident that the results will be accurate enough the educational purposes of CO2nnect.

However, there are several sources of error that could make the results inaccurate. It would be interesting to discuss this in your class.

For example, the amount of CO2 emitted by a car using petrol will depend on many things:

The same would be true for other methods of motorized transport.

The multipliers assume a certain average number of passengers in each mode of transport. This is called the ”average passenger load.”. This could be quite different than the actual passenger load in your situation. For example, if you ride a big bus that is almost empty, or extremely full, the multipliers might not be very accurate for your trip to school.

You might also ask whether the multipliers would vary from country to country. The answer is yes! One reason is that electricity is produced very in different ways. The main source of the electricity in a country (hydropower, coal, nuclear, other) would certainly make a big difference in the amount of CO2 emitted from trains, trams or other transportation running on electricity!

Countries all have their own economies, transport systems and pollution laws, which could also have an effect on passenger loads and carbon emissions – even for the same mode of transport. This would be a relevant topic to discuss this when you compare results from several countries. Unfortunately, reliable multipliers are not yet available for all countries that are calculated the same way.

Theoretically it would be possible to make a calculator that would take all of these things into account. However, today we don’t have all the data needed to find such detailed and accurate multipliers. A calculator like that would be very complicated and it would take a lot of work for pupils to collect the data. We chose to make the CO2nnect calculator relatively simple so that pupils could spend more time learning about their local transport systems and working with others to find sustainable solutions.

There are a few other sources of inaccuracy to be aware of as well. Pupils will be measuring and entering the distance to school and the mode of transport. There will always be some error in these measurements depending on the method used, and the distances are rounded up or down to the nearest kilometer. Some mistakes might also be made when calculating distance or entering the data.

The information on number and proportion of people using the various modes of transport should be quite accurate. There are no multipliers, so errors would only occur while deciding on the mode of transport and registering the data.

Considering all of these possible sources of error, we are still confident that the results of CO2nnect will be accurate enough for you to use your school results to discuss CO2 emissions and work to reduce emissions in your school and local community. They will also be accurate enough for you to compare your school with others in your country and in other countries.