Landscape for looks and efficiency
The deciduous trees on the south side of the home let the sun's heat through during winter.
Question: We want to landscape around our new house with trees that provide shade and enhance the energy efficiency of our home. Where should we plant? And are there good alternatives to grass for ground cover?
Answer: Wise landscaping can do more than just create an attractive yard. It can also lower your utility bills, summer and winter, and improve your family’s comfort year-round.
Trees—one of the key components of residential landscaping design—can have the greatest effect on your utility bills. As moisture evaporates from tree leaves, it cools the air temperature around your home, akin to how perspiration cools your skin. Plus, the proper placement and selection of trees can take advantage of passive solar heating during winter, so you can use less electricity to heat your home.
The primary goal of efficient landscaping with trees is to shade your home during summer, yet allow the sun to pass through during winter.
Before you start planning, determine your temperature zone, which refers to the minimum winter temperature range. (Find a zone map.) If you select species of trees that thrive in a climate more than one or two zones outside your range, they may not do well and may require excessive care.
In an average temperate climate, a typical efficient tree-landscaping plan has deciduous trees to the south, southeast and southwest. The leaves block the sun during summer, but when they fall during winter, the sun shines through to help heat your home. Leave a small gap to the southwest to allow cooler evening breezes to flow through.
Along the north, northeast and northwest sides, plant dense evergreens to block cold winter winds. With shorter winter days and the sun lower in the sky, not much solar heat comes from these directions.
In hot, humid climates, shading during summer is most important. Taller trees should be planted closer to your home to block the summer sun, which is higher in the sky. Leaving a gap for breezes is not as important.
For landscaping at ground level, ground-cover plants and gravel are alternatives to grass. Their advantages and disadvantages depend on your climate, house and yard. Even in the same neighborhood, what is good for one house may not be efficient for another.
Low-growing ground cover near your house can help keep it cool during summer. The foliage prevents the sun’s heat from absorbing into the ground and gives off moisture for natural cooling. In winter, ground cover has less impact on efficiency.
The cooling effect from ground cover is most effective in drier climates, because there is more evaporation. In hot, humid climates, the additional moisture from plants near the house will further increase the relative humidity level. This is a greater problem if you rely on natural ventilation, rather than air conditioning with the windows closed.
Landscaping with gravel can increase the air temperature around your house, particularly in the evening. The thermal mass of the gravel stores the afternoon sun’s heat, which helps in the winter. If you use gravel, make sure it’s shaded by deciduous trees during the summer.
A good location for ground cover is between an asphalt or cement driveway or walkway and the sunny side of your house. Not only does the driveway hold heat, but it radiates the heat to your house. Taller ground cover between the driveway and your house walls can block some of this heat.
Send questions to Energy Q&A.