As far as I understand it, "green material" doesn't mean it's more efficient in operation, it just means that it would be less harmful at the end of the system'

As far as I understand it, "green material" doesn't mean it's more efficient in operation, it just means that it would be less harmful at the end of the system's life. When HFCs from air conditioners, heat pumps, refrigerators, etc. are released into the atmosphere (often when the system is disposed of) they have a disproportionately high greenhouse gas effect compared to vehicle emissions and other common sources.