A City Hall news release today states that Rockefeller Center has installed its “first-ever ‘green’ Christmas tree.”

City Room would have thought that the only truly green Christmas trees are the ones that still have roots in the ground. But Mayor Michael R. Bloomberg has power usage in mind.

When the the Rockefeller Center tree is lighted up on Nov. 28, it will feature 30,000 light-emitting diodes along five miles of wire, reducing energy consumption from 3,510 kilowatt hours to 1,297 kilowatt hours per day, according to Tishman Speyer, the development company that manages Rockefeller Center. The energy saved is equivalent to what a family would use in one month in a 2,000-square-foot home.