I haven't thought about it much until recently, but 9/80 work schedules seem to be really good for the environment. In case you're unfamiliar with the concept, in a 9/80 schedule you work nine days and 80 hours every two weeks and typically get every other Friday off. This is accomplished by working nine hours per day every day except one, instead of eight hours per day over ten days.
So this means you only have to haul yourself to and from work nine times every two weeks instead of ten. That's a reduction of 10%. If your mode of transportation is driving, and you drive to the same workplace every day, that means 10% less driving for work trips. This is particularly useful if you have a long commute.
The results seem to be less traffic, lower emissions from vehicles, less time spent commuting, and lower commuting expenses. The only caveat to that I can think of is maybe people take their extra day off and do traveling they wouldn't otherwise do, thus canceling out some or all of the environmental benefits of less driving for work trips. Anyone have any studies on that?
Another potential problem is that nine hour days can require a lot of endurance to get through and can cause schedule conflicts, particularly for people with children. However, it seems as if 9/80 work weeks and other compressed work schedules could be a great way to get a lot of benefits at practically no cost.