At the height of the COVID pandemic, an estimated 50 percent of all Americans began working remotely. Since then many workers have returned to the office—but around 20 percent have continued to work from home at least part-time.

The benefits of remote work have become a hotly debated topic. Proponents argue that working from home is better for both workers’ health and the planet. And intuitively, it makes sense that cutting out a daily office commute would save a substantial amount of greenhouse gas emissions. Yet there have been few in-depth studies into how sustainable remote work actually is.

A new analysis examines the sustainability question and provides a comprehensive insight into the climate mitigation potential of remote work in the U.S. By looking at five factors, including commuting, noncommute travel, information technology devices, office energy efficiency and residential energy use, researchers were able to calculate how much carbon the average American office employee saves by working from home. The team found that remote work has the potential to reduce an individual’s carbon emissions by more than half—but only if they take the necessary measures at home. The results were published on September 18 in the Proceedings of the National Academy of Sciences USA.

Calculating the carbon cost of remote versus in-office work was a challenge. “This problem is fairly complicated,” says Fengqi You, a systems engineer at Cornell University and co-author of the paper. “The systems involved are complex.”

You and his team were able to obtain a massive anonymized dataset from Microsoft that gave them an unprecedented window into remote workers’ day-to-day energy use and lifestyle. By comparing these data with recorded greenhouse gas emissions from in-person office work, they calculated the actual carbon reduction potential of working from home. Some of the results, You says, were “surprising.”

For example, many previous analyses of remote work assumed that cutting out an office commute meant that workers wouldn’t drive during the day. But You and his team found that this isn’t the case. In fact, remote workers often drive more often than their in-office counterparts by taking several short car trips throughout the day.

The researchers also found that working from home can prompt people to use more energy over the course of a workday on things such as air-conditioning and a dishwasher. And remote workers are more likely to move out of big, centralized cities, where lifestyles are generally less carbon-intensive than in suburban or rural areas.

All of these observations have big policy implications. Recently some politicians have championed working from home as a major climate solution and have credited it with a 95 percent reduction in emissions. Unfortunately, “that’s not true,” You says.

Brian Caulfield, a civil and structural engineer at Trinity College Dublin, agrees. “It doesn’t stand up to scrutiny,” says Caulfield, who was not involved in the study.

This doesn’t mean that working from home cannot lower emissions substantially, however. Biking to a nearby coffee shop with your laptop, for example, is an extremely carbon-efficient way to work. The study found that people who work remotely four or more days a week can reduce their carbon footprint by up to 54 percent, and those who do so up to four days a week can reduce it by up to 29. But these reductions only hold if workers implement strategies such as turning off unnecessary lights and appliances, driving an electric vehicle or sourcing their home electricity from solar panels or wind turbines.

“It’s not all about how many days you work from home,” says Yanqiu Tao, a sustainability engineer at Cornell and first author of the paper. “It’s about how well you live sustainably.”

The study’s authors also point out that office buildings can be made greener. If older buildings were revamped with more energy-efficient appliances and put on a decarbonized grid, then in-office work could match the greenhouse gas emissions of working from home. Taking public transit can also contribute significantly to reducing an individual’s carbon footprint, even if they are working from an office.

Although the paper’s results were specific to the U.S., Caulfield believes that the same basic principles should hold for other industrialized countries. “The kind of patterns we see across the world are very similar,” he says, including in his home city of Dublin.

The biggest takeaway, the authors say, is that remote work is here to stay, and it can absolutely be part of a greener, more sustainable future—but it shouldn’t be seen as a panacea.

“The pandemic has really motivated us to think about [remote work] in a broader and more complex way, as a society,” You says. “So we really need to understand what we are putting into practice.”