Try this test: Take a walk through the woods on a hot day. Notice how much cooler it is? Leaves block sunlight. Take the same walk in the winter. It feels warmer because the trees, now without their leaves, allow sunlight through, while the trunks and limbs serve as a wind-breaker, thereby reducing windchill.
According to the Colorado State University Cooperative Extension, your winter heating bills could be reduced by as much as 25 percent and summer cooling bills by 50 percent if you place trees in the best locations around your home.
The east and west sides are most important to shade because of the path of the sun. Try to keep the south side of your home unshaded so winter sun can warm the house during the cooler months.
The ideal shade tree is about 25- to 50-feet high with a big canopy. A tree that size will partially shade the roof of a one-story home but will not get too big for most properties. You want to plant your trees at least 10 feet from the foundation to prevent roots from breaking through. Plant trees even farther from your house to avoid damaging it in a storm. Your home and garden center can recommend appropriate tree species for your landscape.