A study showed that car-sharing can reduce greenhouse gas emissions from personal transport by 30% or more. Researchers from the University of British Columbia used data from a survey in Metro Vancouver to model the impact on emissions of replacing personal vehicles with access to car-sharing. They found that car-sharing cuts emissions by over 30% even without reductions in distance traveled, mostly due to access to a newer and more optimized fleet of vehicles. When car-sharers also switched to greater public transport use, total greenhouse gas emissions savings could be over 50%.

1. 7/20/2016 Car-sharing can slash greenhouse emissions by one-third - environmentalresearchweb
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environmentalresearchweb
NEWS
Apr 6, 2016
In urban areas, car­sharing organizations are attracting more and more members, who
gain access to a pool of cars that can often be hired for periods as short as one minute. But
when compared with driving your own vehicle, does this form of car­sharing reduce
greenhouse gas emissions? The answer is a resounding yes, with a study showing that car­
sharing can reduce greenhouse gas emissions from personal transport by a staggering 30%
or more (http://iopscience.iop.org/article/10.1088/1748­9326/10/12/124017).
Michiko Namazu (http://ires.ubc.ca/person/michiko-namazu/) and Hadi Dowlatabadi
(http://ires.ubc.ca/person/hadi-dowlatabadi/) from the University of British Columbia used data from a
survey by Metro Vancouver, Canada, to characterize the personal travel habits of different types of
households. They then modelled the impact on greenhouse gas emissions of replacing personal vehicles
with access to car-sharing.
The study examined five factors that could impact emissions: mode shifting (greater use of public
transport, cycling and walking), right sizing (selecting the appropriate vehicle for the task in hand), trip
planning (combining many short trips into one long trip), use of newer cars (car-share fleets are, on
average, much younger than those of typical households) and less macho (car-share fleets tend to buy the
more efficient drivetrains in each vehicle type).
Namazu and Dowlatabadi found that even when people didn’t reduce the distances travelled, car-sharing
cut greenhouse emissions by more than 30%. The majority of this saving came from drivers having access
to a newer and optimized fleet of vehicles. "The effect was much, much larger than we expected," said
Namazu.
Car-share vehicles tend to be newer and more efficient than people’s own cars, and they are less likely to be
over-powered too. What’s more, members gain access to the right-sized car for the task. "Many people buy
cars that are sized to their maximum expected task – a week-long family holiday, for example," said
Dowlatabadi. "This leads them to buy a behemoth that is used for one- or two-person commuting for 51
weeks of the year, so that they have the needed capacity for their annual holiday."
In contrast, when car-sharing organizations have multiple vehicle types, members can choose the car that
fits their needs. "I will use a two-passenger car to take my wife to the movies, and a truck when needing to
bring a new bookcase home," explained Dowlatabadi.
The model showed that when car-sharers also switched to greater use of public transport (for example,
using the shared car for part of their journey and public transport for the remainder), total greenhouse gas
emissions savings could be more than 50%. Different types of households had differing levels of
greenhouse gas savings – child-free families who work away from home have potentially the greatest
impact if they adopted car-sharing as part of their daily routine. The impacts for families with children
were also shown to be significant, whilst retirees had the smallest impact. The findings are published in
Car-sharing can slash greenhouse emissions by one-third

2. 7/20/2016 Car-sharing can slash greenhouse emissions by one-third - environmentalresearchweb
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Environmental Research Letters (ERL) (http://iopscience.iop.org/article/10.1088/1748-
9326/10/12/124017).
The figures from this study are specific to Vancouver, which has an excellent public transport system. "The
mode shifts that are possible here are less likely elsewhere in North America until similar public transport
infrastructure becomes established and socially accepted," said Dowlatabadi. Meanwhile, European cities
with good public transport systems have lower car ownership rates. Nonetheless, the research indicates
that even without the mode-shift to greater use of public transport, urban households in Europe and North
America could reduce their transport greenhouse gas emissions by around 30% by switching to car-
sharing.
Related links
Characterizing the GHG emission impacts of carsharing: a case of Vancouver Michiko Namazu and Hadi Dowlatabadi 2015 Environ.
Res. Lett. 10 124017 (http://iopscience.iop.org/article/10.1088/1748-9326/10/12/124017)
ERL (http://erl.iop.org)
Michiko Namazu, University of British Columbia (http://ires.ubc.ca/person/michiko-namazu/)
Hadi Dowlatabadi, University of British Columbia (http://ires.ubc.ca/person/hadi-dowlatabadi/)
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About the author
Kate Ravilious is a contributing editor to environmentalresearchweb.