I was a green builder long before the term “green” meant “good.”  Back when I started building homes, green usually had a negative meaning to describe inexperience (“Keep an eye on him, he’s a green plumber”) or illness (“You’re looking green today, do you need to go home?”)

One of the clearest definitions I’ve seen for “green” is by the Skyscraper Museum:

GREEN is a term now widely used to describe buildings designed and constructed with minimal negative impact to the environment and with an emphasis on conservation of resources, energy efficiency, and healthful interior spaces.