WE DON'T JUST
CHANGE ONE MONTH.
The most exciting result happens after the challenge. We've learned: an average participant travels > 1'100km more per year by public transport than before the challenge.
WHY THESE NUMBERS
REALLY COUNT.
1 tree-year equals 12.5 kg CO2, the amount a Swiss tree absorbs per year on average (source: myclimate). In just 31 days, our community saved as much CO2 as an entire forest would absorb in a year.
A flight from ZRH to London causes approx. 300kg CO2 (source: myclimate). By giving up the car, together we avoided the emissions of dozens of such flights.
The distance shifted equals several trips around the Earth. A powerful sign of what we can move together when we rethink our everyday mobility.
The carbon footprint of a Swiss household is approx. 28 tonnes per year (source: FSO). Our savings during the 31 days equal the entire annual footprint of several average households.
CUMULATIVE IMPACT OVER 31 DAYS
CO2 reduction grows with every participating location.
OUR CROSS-COMPARISON
Aggregated modal split change across all projects to date.
CITIES AND CANTONS THAT DARED TO CHANGE
Methodology & sources:
We calculate the CO2 saved in three steps: 31 car-free days (daily distance1 × share of private motorised transport1 × 31 days), then the shift to public transport5,6 and car sales3,4. Every car kilometre avoided saves a net 161.7 g CO2 (car fleet minus public transport mix2). The impact over 1 and 5 years takes rebound effects into account7.
- FSO Mobility and Transport Microcensus 2021 (30 km/day, 70% private motorised transport)
- SwissEnergy transport environmental calculator 2025 (car fleet 187.1 g, public transport mix 25.4 g per pkm)
- FSO 2025, mileage of domestic passenger cars and vehicle stock (10'456 km / car / year) · Mileage · Vehicle stock
- 42hacks assumption: 7% of participating households sell their car or take it off the road
- Anonymised, aggregated analysis of the change in participants' public transport use compared to a control group
- 42hacks assumption: 80% of the additional public transport kilometres replace car trips (20% are additional travel or replace cycling and walking)
- 42hacks assumption: from year 2, the behaviour change counts at 80%, car sales from year 4
READY FOR YOUR OWN
MOBILITY ADVENTURE?
Join thousands of people who are changing their mobility habits for good.
Find your challenge