"The general view is home working is always a good thing, but it's never as simple as it appears," said Paul Swift, a consultant for Carbon Trust, a London-based research group that advises companies on sustainability.
"You can have a very efficient building in a city where people are walking or using public transport. If employees working from home are switching on the heating across the entire house, it will be a negative."
Swift and his team confirmed that working at home during the winter can quickly lead to an increase in emissions.
A single hour of extra heating for most households cancels out the emissions saved by avoiding a commute, the Carbon Trust concluded in a 2014 report.
Only those home workers who live far from the office or who would otherwise drive to work contribute to an overall reduction in pollution. Employees whose daily car commute is at least eight miles, who take a bus for 14 miles or travel at least 32 miles by train can cut emissions, the report said. Those who walk or take public transport would increase their emissions by working from home.
Vodafone Libertel BV, a mobile phone provider, has acknowledged similar findings. Home working increases energy and heating use, offsetting the carbon savings from less commuting and smaller office space, according to its latest Environmental Profit and Loss Account.
The general view is home working is always a good thing, but it's never as simple as it appears.
More people than ever are working from home, and advocates say the practice can cut pollution. About 3.7 million employees in the U.S. do so for half their time on the job or more, double the level of 2005, according to the consultant Global Workplace Analytics.
That may contribute a reduction of 51 million metric tons of carbon emissions a year, the equivalent of taking all of New York's commuters off the road, according to the research group that works to help businesses and communities understand the advantages of working from home.
"Barring a national disaster, we see the growth of half- time-plus telework staying at about 5 to 7 percent for the next few years," said Kate Lister, president of Global Workplace Analytics. "The bigger growth will be among less frequent telecommuters.
There we predict growth of 10 percent a year for the next few years."
There isn't much data on global trends. A poll of more than 18,600 people in 26 countries published by Ipsos in 2012 named India, Indonesia and Mexico as the top countries for telecommuting, followed by South Africa, Turkey and Saudi Arabia. Ten percent to 35 percent of the world's workforce worked remotely at least once or twice per week, the report found.
Among environmentalists, there's some suspicion that companies have their own finances in mind when they push employees out of the office.
"Companies are interested in reducing office space for financial reasons," said Swift of the Carbon Trust. "The environmental side is not the highest priority."
