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Plant Trees, Reduce Energy Consumption
Just as strategically placed trees can increase privacy by blocking your home from the street, they can increase energy efficiency by blocking it from the elements. According to the U.S. Department of Energy, "carefully positioned trees can save up to 25% of a household's energy consumption for heating and cooling". For an average home, planting just three will reduce energy bills by between $100 and $250 a year.
Deciduous or Evergreen
Generally speaking, deciduous trees are planted to provide cooling shade in summer and warmth from the sun when they shed their leaves in winter. When temperatures are warm, sunlight absorbed through the roof and passing through windows is the reason most people turn on air conditioners. To keep the home naturally cool, species with high crowns should be planted to the south to shade the roof, while smaller trees are planted to the west to shade windows from the afternoon sun.
In colder regions, homes may not require shading, but may be more susceptible to icy winter winds. Evergreens planted to the north and northwest can reduce heat loss by acting as a buffer. They can be planted either as an insulating row about five feet away from the house, or as a multi-layered windbreak — which is more effective, but also needs more space. Combined with a wall or fence, evergreens can deflect wind upwards and over your home. But avoid planting them along the south wall if you're counting on some winter sun for warmth.
Climate
The first thing to consider, when planning a landscape design to improve energy efficiency, is the climate and microclimate. Decide which of the following best describes the region where you live:
Temperate - Temperate zones offer a mix of warm and cold, and require a strategy that maximizes sunshine in winter and shade during summer. You'll want to break icy winter winds, while directing lighter summer winds toward the home.
Hot-arid - In regions that are hot and dry, the main goal is to provide cooling shade to windows, walls and roofs. If your home is air conditioned, you'll want to put up barriers to deflect the wind, which adds unnecessary heat and makes your air conditioner work harder. If it isn't, winds encourage natural cooling and should be channeled toward the home.
Hot-humid - As with hot and arid regions, the goal here is to plant trees that shade windows, walls and roofs from sunlight, and to either deflect or encourage winds based on whether your home is air conditioned. However, avoid planting trees or shrubs close to the home if they require frequent watering, because this will add to the humidity.
Cool or cold - In regions that are primarily cool, windbreaks are especially important. If summers are hot, you may still want trees that offer shade — providing they also allow sunlight during winter.
Another consideration is microclimate, which refers to the specific location of your home. The Department of Energy explains it this way: "If your home is located on a sunny southern slope, it may have a warm microclimate, even if you live in a cool region. Or, even though you live in a hot-humid region, your home may be situated in a comfortable microclimate because of abundant shade and dry breezes. Nearby bodies of water may increase your site's humidity or decrease its air temperature." Each of these factors would require a different landscaping strategy.
Species
Choosing the right type of tree is important for several reasons. Native species, for example, are well adapted to the region and tend to have a higher survival rate — which is important when you consider that more than half of all trees planted in urban environments die within the first few years. Particular species can also help to meet a variety of landscaping goals. If you live in a dry climate or summer droughts are common, you'll want species that require very little water — something known in landscaping terms as xeriscaping. Some species are also naturally resistant to pests, which reduces the need for chemical pesticides.
Added Benefits
In addition to reducing energy consumption, trees have a variety of other benefits that make them an excellent choice for home owners. They absorb carbon dioxide from the atmosphere while releasing clean oxygen. They reduce soil erosion, provide habitat for birds and other wildlife and make communities more appealing. They can also increase the value of your home by up to 20%.
Links:
The following links offer a wealth of useful advice for planting trees to maximize energy efficiency, from creating a landscaping strategy, to choosing appropriate species and making sure that the trees you plant survive. Your local nursery will be able to provide information specific to your region.
American Nursery & Landscape Association
www.anla.org
American Society of Landscape Architects
www.asla.org
U.S. Department of Energy
www.eere.energy.gov
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