The critical exposures of a building in the northern hemisphere are those facing south and west. They receive the most direct sunlight in the summer and account for a majority of the building’s heating load. Shading of windows with blinds or awnings reduces this heat gain somewhat, but trees do even more: They shade the walls and even the roof of one-story structures. Deciduous trees, in addition, lose their leaves in the winter to expose the building to the warming sunlight.
Landscaping has another benefit. A portion of the heat striking the lower walls of a building arrives indirectly, reflected from rocks, sidewalks, and parking lots or re-radiated from these surfaces. Shrubs, grass, and ground cover reduce this heat gain by blocking the heat-transfer path and by dissipating the thermal flow. Shrubs are even more effective if they shed their leaves in the winter or can be trimmed to open the thermal path to the south- and west-facing building walls in the winter.
One note of caution: your termite inspector doesn’t like to see shrubs too close to the house. Mulch or a thick layer of leaves around the foundation perimeter keeps the ground moist all the time, creating the perfect conduit for termites into your home. In other words, don’t plant the shrubs too close to the foundation ~ you’ll need space when the painters come every so often to repair the siding, or when the roofers put on a new roof.
Large shade trees add a lot of value and “curb appeal” to a property. It’s ironic that developers go into an area, level all the old-growth trees ~ then the new homeowners devote the next 20 years to growing nice shade trees. The ideal solution is to plant a mixture of oaks (which grow slowly but have a majestic canopy) and fast-growth trees (including fruit trees, which are always fun). The latter provide immediate relief from the bare-lawn syndrome but have a short lifespan. When the fast-growth trees die, the oaks will be mature and provide bounteous shade.
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Excerpted from Going Green, available as an eBook at this list of eBook retailers online.