GROW: Landscaping for energy conservation | News
Garden enthusiasts count the days until the soil temperature is warm enough to get new plants and shrubs into the soil. They visualize the new colors, the different textures and the general appearance of the landscape.
It is also important to consider how these new and established plantings can affect energy savings. Well-placed trees and shrubs can have a positive effect on heating and cooling costs. Things that garden shed owners need to consider are the angle of the sun, the orientation of the house and the direction of the winter and summer winds. Boy, do the Oklahomans know about wind … and summer heat … and the cold of winter?
It’s no secret how hot an Oklahoma summer can be. Providing shade can significantly reduce the flow of heat into a home, which in turn can help lower your energy bills. Studies suggest that shade can reduce heat flow by up to two thirds. Shading the roof with tall, highly branched trees such as oaks can also help cool. While summer shade is desired to reduce cooling costs, we also want to maximize the sun in the winter cold. Careful tree selection is required to get the best of both worlds.
Features to look for include tall branches that block the summer sun but allow penetration of the winter sun, which hits the house at a much smaller angle. For example, the open branching of the Kentucky coffee tree allows for a more open winter canopy and greater winter sun penetration.
Homeowners also want to consider the timing of the leaf drop. Ideally, look for trees that drop leaves between October 15th and November 15th. Gardeners should avoid trees with conical crowns such as pen oaks and many evergreen plants, as they provide significantly less shade in summer and block out winter sunlight. Plant trees and shrubs to shade south and west facing walls as they will trap plenty of heat from the hot afternoon sun on those long summer days.
Wind is another consideration in landscaping to conserve energy. Your home can lose a lot more heat on cold, windy days than on cold, calm days. Well-placed trees and bushes can absorb winter winds and reduce heat loss. The coldest winds come from the north and northwest. So if you are planning a windbreak it is best to place it on the north and west sides of your home or property.
Foundation plantings are the plant materials that are placed along the perimeter of the house and affect a house’s energy gain and loss in a number of ways. They act as insulation against the wind and reduce air currents near the house. They also create air bubbles that insulate the house. Like wind breaks, evergreen plants have a greater impact on energy savings than deciduous plants.
For more information, see Fact Sheet HLA-6417: Landscaping for Energy Conservation from Oklahoma State University Extension. at http://osufacts.okstate.edu.
David Hillock is a consumer horticulturalist with the Oklahoma State University Cooperative Extension.