After paying your heating bills this winter, you may want to think about planting windbreaks - for landscaping that saves energy dollars.
Winter winds are strong and cold, so when they blow on people or on buildings they pull the heat right out of them. That's the essence of the wind chill factor we hear about on the weather reports each night.
We all know that sun through the southern windows warms us in winter, but we don't always remember that blocking the wind can save energy too. The statistics of how much can be saved are noteworthy.
A well placed windbreak can reduce wind velocity by 85%, and reduce winter heating costs by 10% to 25%.
Windbreaks work either by deflecting the wind up and over a building thereby forming a protective wind shadow, or by catching it in the twigs and branches of a double or triple row of trees which breaks up its speed.
Tests done on the western prairies showed that a good windbreak gives best wind shadow protection downwind (where the wind blows to) for a distance 3 to 5 times the height of the trees. It also blocks the wind a short distance upwind (where the wind blows from).
A Wind Shadow
An evergreen windscreen breaks the force of the wind and creates a protective wind shadow in front and behind. Dead air space protects the house.
Another way to lower the wind chill on a house is to put a row of evergreen shrubs right in front of the wall. They will stop the wind and form a protective dead air space between themselves and the wall. When that space fills with snow, it acts as insulation saving even more energy.
Tests on the prairies also showed that if farmers cut down all their windbreaks and burned the wood for fuel, then for ever after, the energy loss from future winter winds each year would about equal the heat from the wood burned up in that one year alone.
The best windbreaks are made from several layers of plant material. Ideally evergreens are combined with deciduous trees or large shrubs to break up the force of the wind. A good windbreak would have an evergreen screen, behind small flowering trees or large bushes such as forsythia.