Green and Grey

I saw my brother-in-law this weekend who is a contractor in PA.  He mentioned that he was building a Green and Grey house.  I had no idea what the "Grey" was.  Green obviously means environmentally conscious but I learned that grey means that clients are requesting the installation of grab bars and building single level homes for retirement age.  I think this might be a suburban thing??

Not sure how good this is going to be for me - I like that my clients hop around and move houses - nothing like repeat business!!