Just in the last month I’ve noticed signs of a major shift in green building practices around the country.

Green building codes and ordinances are springing up all over the place. We may be seeing the beginning of one of the best environmental stories of 2007.

Washington D.C. got a lot of attention early in December for passing rules that will force private development to green up (although not until 2012). Now Boston is entering the game, forcing all private development over 50,000 sq. ft. to meet LEED‘s minimum criteria (26 out of 69 possible points). In addition to large metro areas, smaller cities and counties are greening their codes or making their public buildings green up. The list I pulled from google this morning includes: Livermore, Calif., Santa Cruz, Calif., Montgomery County, Va., Chatham, N.C., and Babylon, N.Y.

All of these were announced this month! Most green building stories profile specific buildings — but if what’s happening in these cities is an indication of what’s in store for the coming year, green building may be going mainstream in an even bigger way than I imagined.

Many of these cities are incorporating LEED or modeling their guidelines on LEED’s point system, but there’s a lot of variation.

Time will tell how this trend develops, and how effective these various codes will be. I would like to see more coordination of green building standards between communities, because a green code that only specifies materials has very little in common with a code that gets into energy, materials, site, IAQ, and water. But most citizens, if they are even paying attention to these issues, will be happy to know their community is greening their codes at all.

That said, I do think these code changes are absolutely essential to advancing green practices. Seeing this uptick in the number of communities institutionalizing green building was a holiday present I hadn’t anticipated.