A home shaded by three trees can cut energy bills by 50% in the summer thanks to shade and transpiration. Those same trees serve as windbreaks for those cold winter winds, and reduce heating costs by 30%. As few as three trees properly positioned can save the average household between $100 and $250 annually in energy costs.
Rows of trees reduce windspeed by up to about 85%, with maximum reductions increasing in proportion to visual density. Because even a single row of dense conifers can cause large reductions in windspeed, effective windbreaks can be planted on relatively small house lots. Compared with an open area, a good windbreak that does not shade the house will save about 15% of the heat energy used in a typical home.
Image from American Forests - How to Plant a Tree