When they grow tall they will shade a part of the roof. They also will shade driveways, sidewalks and patios that can bounce heat to the building. Homes with large windows and walls without insulation will benefit most from shading. To keep themselves cool, trees pump water from the ground into their leaves. As this water evaporates from the surface of the leaves, it cools the tree.
Some trees lose their leaves in winter.
These are called deciduous trees. Deciduous trees are usually better for shading, because their canopies are broad and dense. When the leaves fall in the winter, deciduous trees allow solar heat to reach the building. DWP offers a free booklet about shade trees titled, Smart Planting for the New Urban Forest. Trellises Trellises are permanent structures that partially shade the outside of a building.