Setting "green" as a goal in a project, including software, might increase the possibility to get funding grants. YC "Requests for Startups" recently wrote about how much money there is for grabs in "climate tech": https://www.ycombinator.com/rfs
Quite true, that maybe a target, but still it's quite hard to achieve due to 3rd party services you would use, or even simply the hosting you would upload your site on.