I understand it to mean that they use less energy than they used to. It's a very broad term.
No datacentre is really green, as it consumes huge amounts of electricity. What it might be is more efficient - ie a better PUE (Power usage effectiveness) - in how it cools the equipment and in other power consumption areas. It's a bit of a stretch in my view to call it green.
Hello there , i agree with mdubash that this is simple term used to take effect and sound good as green hosting . There is only a relaxation to make the use reliable.
Green hosting is when a company does all they can to reduce their "footprint" on the environment. Some companies try to use renewable energy or to use hosting equipment that is more energy efficient Companies can be green by attempting to use systems that bring cool air from the outside rather than using energy hogging air conditioners These are just some examples.
A green host tries to make less waste from their data center. They also work to use less energy sources that are not renewable. Many are starting to use renewable energy sources for their data centers or at least to run certain areas of data centers.
A host who is attempting to be green will take all measures to reduce what is referred to as their footprint on the environment. They will work to reduce or eliminate any wastes from their data center facilities. They will also look for ways to reduce their use of energy (ideally they will use some form of renewable energy).
A web host would be one that powers their entire setup using clean energy sources. Some hosts claim to be green but are still using energy sources that are not clean and simply purchase offsets.. Simply they are not liars..
You really need to look into the green advertisements, usually it's a scam, but there are some companies out there that actually recycle everything, including the power they use, with wind farms and solar panels. Then there are companies that BUY energy credits, which puts the entire system to shame.