Fully remote workers are responsible for less than half of the greenhouse gas full-time in-office workers emit, finds new research published Monday in the Proceedings of the National Academy of Sciences journal. In the U.S., one day of remote work cuts emissions by only 2%, owing to the offset impacts of things like electricity and home heating. But working from home part-time—between two and four days a week—brings personal emissions down by anywhere from 11% to 29% compared to in-person workers. That climbs to 54% fewer emissions for those working from the couch five days a week compared to those who head to the office.

For the most part, the researchers found, emissions stem from rush hour vehicle congestion, which remote workers sagely sidestep. Meanwhile, the commute’s effects have intensified; many workers moved farther away from major cities during the pandemic, which means that when they do commute, they’re traveling more miles and releasing more carbon into the air. 

“Remote or hybrid work not only offers flexibility to employees, but also provides environmental advantages,” co-author Fengqi You, an energy systems engineering professor at Cornell University, tells Fortune. But “concerns about productivity, in-person interactions, and collaboration still exist.” His team at Cornell, he adds, has been hybrid since 2020.

An employer who’s supportive of remote work—and conscious of climate impact—should allow two or three days of remote work per week, You went on. In-person work can carry such a massive carbon footprint, in part, because office spaces “are unlikely to be shared effectively if a worker needs to use the space for four out of the five work days per week.” The findings should galvanize bosses to think twice about mandating daily in-person attendance—or renting unnecessarily large office spaces that only halfway fill up.

Remote workers still travel, albeit to anywhere but the office. And their home utilities—such as a personal printer or monitor—were less efficient than high-capacity office ones. In order to maximize climate-friendly impact, workers both at home and at work need to be thoughtful about minimizing their personal energy usage, consider driving an electric vehicle, and limiting travel, both for business and pleasure.

The worst emissions come from business travel, which could be going extinct too

For most white-collar industries, five days of in-person work per week will likely never be the norm again. That’s good news for the environment, based on the Cornell findings. So, too, is that the pandemic may have killed off another mainstay: business travel.

An April 2023 Deloitte report found that the growing ESG initiatives were also likely to put a cap on how many trips employers would be willing to send their staff on in the future. “Climate concerns will likely put a cap on corporate travel gains for several years to come,” Deloitte analysts wrote. “Four in 10 European companies and a third of U.S. companies say they need to reduce travel per employee by more than 20% to meet their 2030 sustainability targets.”

Perhaps eco-friendly workers shouldn’t hold their breath that companies will do the right thing. While more than 200 of the world’s largest companies have vowed to reach net-zero emissions by 2040, they’re only set to reduce them by 40% by then, a 2022 New Climate Institute report found.  “We went in naively optimistic about what we might see,” Thomas Day, a New Climate Institute analyst, said last year. “We were disappointed we didn’t find a lot more creativity that we expected to find.”

Granted, it’s not all companies’ fault, and remote workers’ personal travel and energy usage can rack up a sizable carbon footprint even without a commute. The Cornell researchers confirmed that their  findings deeming remote workers more climate-friendly aren’t quite definitive. 

“They are susceptible to changes in the decisions regarding individuals’ lifestyles, employer’s work and office space arrangements, and government’s sustainability policies,” Yanqiu Tao, a Cornell engineering graduate student and lead author of the study, tells Fortune. “The uncertainty can be quite large, so we should be careful when interpreting the results and think about how we can act and trade off to achieve better climate sustainability against many real-world constraints.”

Even so, many traditional businesses like banks and law firms are unlikely to be swayed on remote work by a climate argument. Thus, the onus is on workers to nix the single-use plastics and switch to fluorescent bulbs.