Trees reduce yearly heating and cooling costes by 2.1 billion dollars in the U.S.Trees provide wind protection and shade.One shade tree can keep a building up to 20 degrees cooler in the summer!

• 在美国由于树木所起的作用；每年可以减少热量使气温凉快；从而节省用电大约21亿美元.；树木还可以挡风遮雨