Infiltration or air leakage can account for as much as one-third of heating losses in some buildings. Cold, outside air flows in through cracks around windows and doors, and even through pores in walls. This produces drafts that may cause you to compensate by raising the thermostat to unreasonable levels just to maintain a modicum of comfort. Both windbreaks and foundation plantings can cut down the penetrating power of the wind.

Windbreak Benefits

Studies of windbreaks show that windbreaks can reduce winter fuel consumption by 10 to 30 percent. One study in Nebraska compared fuel requirements of identical test houses which maintained a constant inside temperature of 70 degrees F. The house protected by a windbreak used 23 percent less fuel. In 1 month, an exposed, electrically heated house in South Dakota used 443 kilowatt-hours to maintain an inside temperature of 70 degrees F. An identical house sheltered by a windbreak used only 270 kilowatt-hours. The difference in average energy requirements for the whole winter was 34 percent.

The amount of money saved by a windbreak will vary depending on the climate of the area, location of the home, and the construction material and quality. A well-weatherized house with adequate ventilation won't benefit from windbreaks as much as a poorly weatherized house. In addition to reducing the force of the wind, windbreaks also can reduce the wind-chill impact on people outside the house.

Windbreaks can be located to control snow too, reducing the energy required to remove snow from around homes, buildings, and roads. Make sure windbreaks are located correctly to have the desired effect on drifting snow.

The height and density of trees determine the amount of protection they will provide. Windbreaks of 2 to 5 rows of trees and shrubs generally provide good protection. Evergreen trees provide the best protection, although low, branching deciduous trees can significantly reduce wind speed. Even a single row of evergreen trees will give some protection.

Windbreaks reduce wind velocity significantly for a distance of about 10 times the height of the trees. Maximum protection is provided within a distance of 5 times the height of the trees. Thus a windbreak 30 feet high protects an area extending as far as 300 feet downwind and some protection is provided for as far as 20 times the height of the trees.

Foundation Planting

Trees and shrubs planted close to buildings reduce wind currents that otherwise would chill the outside surface. Foundation plantings create a "dead air" space which slows the escape of heat from a building. These plantings also help reduce air infiltration around the foundation of the house. Evergreen trees and shrubs are thicker and are more effective than deciduous plants. To be most effective, the evergreens should be planted close together to form a tight barrier. In summer, the same dead air space helps insulate your home from hot, outside air reducing the need for air conditioning.

(Originally published as "Landscaping to Cut Fuel Costs," by Jerome R. Smith, former Extension Housing Specialist, in The Virginia Gardener Newsletter, Volume 5, Number 9.)