In 2001 , following the September 11 attacks , the tree was again decorated in hues of red , white and blue . In 2007 , the tree went " green " , converting to energy-efficient lighting with LEDs . The LEDs use 1,200 fewer kilowatts of electricity per day , enough to power a 2,000-square-foot home for a month . Also since 2007 , each year after display , the tree has been milled into lumber and donated to Habitat for Humanity for use in house construction . Since 2011 , the tree lighting ceremony has been followed by the singing of Joy to the World
September 11 attacks
September 11 attacks
Rockefeller Center Christmas Tree