Changes to your home landscape may lower your energy costs throughout the year. The United States Forest Service has reported that, for example, just three optimal and well-placed landscape trees can reduce the annual heating and cooling costs of a well-insulated northern Illinois home by 6.5 percent annually. Here are tips for choosing and siting plants as energy savers.
Winter Warmers
Trees and shrubs can’t change the air temperature, but they can stop the wind from blasting a home and chilling us with frigid drafts. Here’s how to site woody plants to make the house feel warmer:
Plant shrubs and small trees near the house’s foundation, where they’ll trap air next to the building. This layer of air will buffer indoor temperatures against outdoor temperatures. Just be sure to site the plants so there will be a one-foot clearing between them and the building when they reach their mature size, for maintenance.
Plant a windbreak of evergreen trees or shrubs to the north and northwest of the house. These plants will block the winter wind and send it up and over the home, slowing heat loss from the walls. A windbreak will protect about 10 times the distance of its height. In other words, a row of 10-foot-tall shrubs will shield the area within 100 feet behind it.
Related: "What Wind Chill Means for Plants"
A windbreak can be a single row, but two or three rows of plants works better. To make it even more effective, stagger the rows.
Plant short shrubs on the windward side of the home, where they will stop snow from blowing and drifting against the building.
When choosing trees for summer shade, pick deciduous types so that they’ll allow warming sunlight through in the coldest months.
Summer Coolers
Anyone who has entered the forest on a hot summer day, or simply stepped into the shade of one oak or maple, knows the cooling power of trees. Strategic placement of landscape trees can direct this power toward the home:
Plant trees and shrubs to block the roof and west and southwest walls and windows from strong summer afternoon sun.
Plant deciduous trees with high, spreading crowns to the south, where the summer sun is highest at midday and most intense.
Plant shorter or low-branched deciduous trees on the west wide of the building to provide shade from the lower angles of the afternoon sun.
Additional shading of walls can be achieved with climbing vines; plant deciduous types against south-facing walls and evergreen vines on the others.
Use plants to shade bare ground and paved surfaces.
Site small trees or large shrubs to shade an outdoor air-conditioning condenser to increase its efficiency. Just be sure to leave a three-foot clearance around the unit for maintenance and air circulation.
