In the Garden:
This big ol' maple tree shades the southeast side of our house.
I've been watching the progress of the new development going in next door to us, and as is so often the case, the first thing the developer did was cut down the trees and strip the area of all plant life. Now, the first two houses are in, and I'm struck by how stark they look, and also by how the summer sun beats down on them unrelentingly. A few well-placed shade trees would do so much to not only improve the look of the properties, but also cut down on cooling bills. Sadly, I don't see evidence of any plantings other than struggling lawns.
Contrast this with our 90-year-old house. Someone had the sense to plant the right trees in exactly the right spots -- or perhaps leave certain existing trees in place. Maples provide shade in the heat of summer; evergreens act as winter windbreaks. Both are a boon to the aesthetics and the energy efficiency of the house.
Landscaping to Conserve Energy
In the era before homeowners could flip a switch to turn on the heat or air conditioning, landscaping played an important role in the comfort of a home. People planted trees and shrubs in strategic locations to mitigate hot summer sun and cold winter winds, while making the most of cooling summer breezes and radiant heat from the winter sun.
What happened to this commonsense approach to landscaping? Perhaps it's simply expediency -- it's easier to strip the land rather than maneuver heavy equipment around existing trees. Perhaps it has to do with our legacy of cheap electricity and fuel. When electricity was inexpensive and heating oil was fifty cents a gallon, conserving them wasn't a high priority. It can be hard to convince people of the importance of conserving natural resources until their pocketbooks and wallets are affected. So, that brings us back to the trees.
Using Trees and Shrubs Effectively
Our house is a perfect example of landscaping to conserve energy. There are tall deciduous trees on the southeast and southwest sides that shade us from the morning and late-afternoon summer sun. Once leafless in autumn, these trees allow the winter sun to reach the house. Due south, the yard is treeless, so the midwinter sun, which is low in the sky, can warm the house unimpeded. (In summer, the midday sun is so high in the sky that trees on the south side wouldn't provide much shade unless they hovered over the house.)
On the northwest -- and windiest -- side of the house there are evergreens. Two huge hemlocks and several 15-foot-tall yews situated about 20 feet from the house break the wind and offer a visual barrier between us and the houses next door. Rhododendrons near the house further insulate us from the cold, and grace us with a beautiful show of flowers, too.
What a contrast, both aesthetically and practically, to the new, treeless development!
How Much Can You Save?
According to a page on the EPA Web site, "Strategically planted trees alongside buildings can decrease indoor temperatures by more than 15 degrees on hot, sunny days, and allow window air-conditioning units to operate up to 10 percent more efficiently."* A study conducted in California concluded that cooling energy savings ranged between 7 and 40 percent when container-grown trees were located in different positions around a house.** These savings add up, especially now that utility rates are skyrocketing.
The Other End of the Spectrum
In addition to the new, treeless development next door, there's a huge, high-end development going in about a mile away. Here the builders left most of the trees standing, and homeowners must get permission from the association to cut one down. Although brand new, the development already looks established because of the presence of so many large trees, and is much more in keeping with our wooded mountain environment. The downsides are that most homeowners can't have vegetable gardens because the lots are so shady, and there is little natural light to brighten the indoors of the homes.
There has to be some middle ground, between stripping all the trees and prohibiting the removal of any of them. Although, if I had to choose, I'd choose the latter.
*See "Tree Planting Program in Los Angeles" on http://www.epa.gov/globalwarming/greenhouse/greenhouse14/short.html
**See "How Much Energy Can Shade Trees Save?" on http://www.epa.gov/heatisland/strategies/vegetation.html
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