Here is more detailed information on how we calculate CO2 footprint:

CO2

 

The Carbon Emissions factor θ is calculated in government laboratories where vehicles are rigorously tested
For the vehicles considered in the National Science Experiment, the values are calculated to be:

Mode CO2 Factor θ Notes References
Walking 0 Although you should consider the food that you eat as being part of the CO2 contribution that you make as it is digested and turned into energy Emissions by transport type
MRT 13 g/km This is calculated by assuming an average number of riders in a train, and how much electricity the train uses to move, combined with the CO2 produced when generating electricity in Singapore LTA Master Plan 2013 (PDF, page 43)
Bus 19 g/km This is calculated by assuming an average number of riders in the bus, and the CO2 emitted by the average bus burning diesel fuel. The km is per person travelling, meaning this is lower than a car LTA Master Plan 2013 (PDF, page 43)
Car 187 g/km Because a car has to move more mass for each individual rider, the CO2 per km is much higher LTA Revised Carbon Emissions Vehicle Scheme

New or old – which is greener?

Air-con 400 g/kWh Using air-conditioning consumes electricity, and for the NSE the average amount of CO2 produced when a kWh of electrical energy is generated is used as a factor to contribute to your personal footprint Breakdown of a typical person’s carbon footprint

Carbon emissions from air-conditioning