Want to save money on your energy bill without investing in expensive retrofits and renovations? Get a shovel. Strategically planting trees and shrubs around your home is a tried-and-true way to save during winter weather – and warm weather when the air-conditioning runs many hours a day. Now is the perfect time to plant trees.
For areas where sunlight can come in through windows for natural warmth in the winter, choose deciduous trees that lose their leaves in the fall – with high, spreading crowns that can provide maximum shading during summer. You also can plant low shrubs near your foundation to help insulate it from cold winds from the north and west
During warm-weather months, solar heat absorbed through your home’s windows and roof increases your cooling costs, but – depending on the location and orientation of the trees and your house – you can gain significant energy savings by planting shade trees. In summer, a tree’s shade can cool surrounding air temperatures by as much as 9 degrees, and air temperatures directly under trees can be as much as 25 degrees cooler. This means that if your home currently is unshaded, you could be able to cut summer air-conditioning costs by 15 to 50 percent.
Although a slow-growing shade tree may require many years of growth before it shades your roof, it generally will live longer than a fast-growing tree. Also, because slow-growing trees often have deeper roots and stronger branches, they’re less prone to breakage by windstorms or heavy snow loads. Slow-growing trees also can be more drought resistant than fast-growing trees.
Plant trees far enough away from your home so that when they mature, their root systems won’t contact the foundation – and branches can’t damage the roof. Also make sure trees won’t grow into your electric co-op’s power lines – and that branches damaged during a storm can’t fall into the lines.
A 6- to 8-foot deciduous tree planted near your home will begin shading windows the first year. Depending on the species and your home’s design, the tree should start shading the roof in 5 to 10 years.
Also consider shorter trees, shrubs and groundcover plants to shade the ground and pavement around the home, reducing heat radiation and cooling the air before it reaches your home's walls and windows. Use a large bush or row of shrubs to shade a sidewalk or driveway, plant a hedge to shade a sidewalk and build a trellis for climbing vines to shade a patio.
In addition, shading the coils of your outdoor air-conditioning unit or heat pump has the potential to modestly reduce energy demand. But if done improperly, there could be a net increase in energy use. Researchers from the Florida Solar Energy Center found that effective shading of an air-conditioning unit could yield energy savings of 6 percent, but an improper setup could result in a drop in efficiency of up to 15 percent. This drop in efficiency happens when vegetation blocks proper airflow to the unit or traps too much heat near it. Plan about 3 feet of clearance – or whatever the manufacturer of the equipment recommends. Also be sure to frequently check the size of plants near the unit, because during the growing season the plants can creep closer to the system and interfere with proper air circulation.
For details on using shade trees to save energy, check the U.S. Department of Energy’s Energy Efficiency and Renewable Energy website; go to its Energy Savers Landscape page at http://energy.gov/public-services/homes/landscaping. You’ll also find information about planting windbreaks and landscaping for water conservation.