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	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).

Landscape Windbreaks Properly selected and placed landscaping can provide excellent wind protection, or windbreaks, which will reduce heating costs considerably. Furthermore, the benefits from these windbreaks will increase as the trees and shrubs mature. To use a windbreak effectively, you need to know what landscape strategies will work best in your regional climate and your microclimate. Basically, a windbreak can lower the wind chill near your home. Wind chill occurs when wind speed lowers the outside temperature. For example, if the outside temperature is 10°F (-12°C) and the wind speed is 20 miles per hour (32 kilometers per hour), the wind chill is -24°F (-31°C). A windbreak will reduce wind speed for a distance of as much as 30 times the windbreak's height. But for maximum protection, plant your windbreak at a distance from your home of two to five times the mature height of the trees. The best windbreaks block wind close to the ground by using trees and shrubs that have low crowns. Dense evergreen trees and shrubs planted to the north and northwest of the home are the most common type of windbreak. Trees, bushes, and shrubs are often planted together to block or impede wind from ground level to the treetops. Evergreen trees combined with a wall, fence, or earth berm (natural or man-made walls or raised areas of soil) can deflect or lift the wind over the home. Be careful not to plant evergreens too close to your home's south side if you are counting on warmth from the winter sun. If snow tends to drift in your area, plant low shrubs on the windward side of your windbreak. The shrubs will trap snow before it blows next to your home. In addition to more distant windbreaks, planting shrubs, bushes, and vines next to your house creates dead air spaces that insulate your home in both winter and summer. Plant so there will be at least 1 foot (30 centimeters) of space between full-grown plants and your home's wall. Summer winds, especially at night, can have a cooling effect if used for home ventilation. However, if winds are hot and your home is air conditioned all summer, you may want to keep summer winds from circulating near your home.
Landscaping and Your Regional Climate The energy-conserving landscape strategies you use should depend on which region you live in. The United States can be divided into four approximate climatic regions: temperate, hot-arid, hot-humid, and cool. See the map to find your climatic region. Below you'll find landscaping strategies listed by region and in order of importance.

	Temperate Region Maximize warming effects of the sun in the winter. Maximize shade during the summer. Deflect winter winds away from buildings. Funnel summer breezes toward the home. Hot-Arid Region Provide shade to cool roofs, walls, and windows. Allow summer winds to access naturally cooled homes. Block or deflect winds away from air-conditioned homes. Hot-Humid Region Channel summer breezes toward the home. Maximize summer shade with trees that still allow penetration of low-angle winter sun. Avoid locating planting beds close to the home if they require frequent watering. Cool Region Use dense windbreaks to protect the home from cold winter winds. Allow the winter sun to reach south-facing windows. Shade south and west windows and walls from the direct summer sun, if summer overheating is a problem. It's also important to consider your home's microclimate in your landscaping strategy.
Mature deciduous trees provide shade in the summer and sunlight filtration in the winter. Photo credit: John Krigger, Saturn Resource.
	Landscaping and Your Microclimate The climate immediately surrounding your home is called its microclimate. When landscaping for energy efficiency, it's important to consider your microclimate along with your regional climate. Your home's microclimate may receive more sun, shade, wind, rain, snow, moisture, and/or dryness than average local conditions. 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. Microclimatic factors also help determine what plants may or may not grow in your landscape.
Landscape Shading
A trellis with a climbing vine can shade a home and allow air circulation. Photo credit: John Krigger, Saturn Resource.	Solar heat absorbed through windows and roofs can increase your air conditioner use. Incorporating shading concepts into your landscape design can help reduce this solar heat gain, reducing your cooling costs. Shading and evapotranspiration (the process by which a plant actively moves and releases water vapor) from trees can reduce surrounding air temperatures as much as 9° F (5°C). Because cool air settles near the ground, air temperatures directly under trees can be as much as 25°F (14°C) cooler than air temperatures above nearby blacktop. Using shade effectively requires you to know the size, shape, and location of the moving shadow that your shading device casts. Also, homes in cool regions may never overheat and may not require shading. Therefore, you need to know what landscape shading strategies will work best in your regional climate and your microclimate. Trees can be selected with appropriate sizes, densities, and shapes for almost any shading application. To block solar heat in the summer but let much of it in during the winter, use deciduous trees. To provide continuous shade or to block heavy winds, use dense evergreen trees or shrubs. Deciduous trees with high, spreading crowns (i.e., leaves and branches) can be planted to the south of your home to provide maximum summertime roof shading. Trees with crowns lower to the ground are more appropriate to the west, where shade is needed from lower afternoon sun angles. Trees should not be planted on the southern sides of solar-heated homes in cold climates because the branches of these deciduous trees will block some winter sun. Although a slow-growing tree may require many years of growth before it shades your roof, it will generally live longer than a fast-growing tree. Also, because slow-growing trees often have deeper roots and stronger branches, they are less prone to breakage by windstorms or heavy snow loads. Slow-growing trees can also be more drought resistant than fast-growing trees. A 6-foot to 8-foot (1.8-meter to 2.4-meter) deciduous tree planted near your home will begin shading windows the first year. Depending on the species and the home, the tree will shade the roof in 5–10 years. If you have an air conditioner, shading the unit can increase its efficiency by as much as 10%. Trees, shrubs, and groundcover plants can also shade the ground and pavement around the home. This reduces heat radiation and cools the air before it reaches your home's walls and windows. Use a large bush or row of shrubs to shade a patio or driveway. Plant a hedge to shade a sidewalk. Build a trellis for climbing vines to shade a patio area. Vines can also shade walls during their first growing season. A lattice or trellis with climbing vines, or a planter box with trailing vines, shades the home's perimeter while admitting cooling breezes to the shaded area. Shrubs planted close to the house will fill in rapidly and begin shading walls and windows within a few years. However, avoid allowing dense foliage to grow immediately next to a home where wetness or continual humidity are problems. Well-landscaped homes in wet areas allow winds to flow around the home, keeping the home and its surrounding soil reasonably dry.
	Landscaping Careful selection and positioning of plants can provide summer shading; act as a buffer against hot winds; and maximize the effect of cool changes. Tall, deciduous canopy trees provide shade to north windows while still allowing winter sun through. Smaller, deciduous shrubs are useful for shading east and west windows and walls. Low shrubs, lawn or even a water feature to the north will help cool hot summer winds. Avoid paving in front of north windows— use ground covers to reduce the effects of reflected heat. Planting deciduous creepers over a north facing pergola will provide shade for windows and walls, as well as a pleasant outdoor entertaining area.

	Window shading It is better to stop the sun’s heat from reaching the glass, rather than deal with the problem once the heat has entered your home. External shading is much more effective at keeping your home cool than internal blinds or curtains. Using both external and internal window coverings; however, will provide maximum protection. The most appropriate method of shading your windows depends on which direction they face. North-facing windows Fixed horizontal shading devices such as eaves and pergolas are ideal for shading north windows. Properly designed, they will block the high summer sun, while still allowing the low level winter sun to shine through. Adjustable vertical shading such as canvas blinds, awnings, roller or conventional shutters are also suitable for shading north windows. East and west-facing windows If not shaded, these windows can cause severe overheating in summer. External vertical shading devices (canvas blinds, awnings or shutters) are recommended. Eaves, pergolas and even verandahs have only limited effect as they do not block out the lower altitude morning and afternoon sun. Skylights and roof glass Without external shading, skylights and roof glass can pose major problems requiring expensive solutions. Always try to provide external shading. Shade cloth is an inexpensive solution; however, other specialized products are also avail-able. Many roof windows can have internal blinds fitted. External blinds fitted on rollers are available for roof glass from many blind suppliers. Tinted glass and reflective films These products reflect and absorb heat, keeping your home cooler. However, be cautious about using them, particularly on north windows, as they reduce the amount of light and heat entering rooms in winter as well as summer. They may be useful for large areas of unprotected glass facing east and west, and for roof glass.