Green construction practices aim to cut back the environmental effect of buildings, so the very first rule is: the greenest construction is the construction that doesn't get constructed.
New construction almost always degrades a construction site, so not construction is preferred to green construction.
The 2nd rule is every construction ought to be as little as possible.
The 3rd rule is: do not contribute to sprawl (the tendency is for metropolises to spread out in a disordered fashion).
Regardless how much grass you put on your roof, regardless how energy-efficient windows, etc., you utilize, if you contribute to sprawl, you've defeated your purpose.
Urban infill sites are preferred to suburban "greenfield" sites.
