Keep energy conservation in mind when planning landscape

Monday, May 9, 2016

When homeowners are planning their landscapes, most often they are focused on the overall look of the finished project.

However, a well-planned landscape also can have a direct impact on your energy bills, said David Hillock, Oklahoma State University Cooperative Extension consumer horticulturist.

Most of the time homeowners are thinking mainly about what flowers, trees and shrubs to plant. Energy conservation typically doesn’t cross their minds,” Hillock said. “They may not realize smart landscaping can go a long way toward increasing the comfort of your home and decreasing heating and cooling costs.”

When designing the landscape, take into consideration of the angle of the sun, the orientation of the home and the direction of the summer and winter winds.

Anyone who has experienced an Oklahoma summer knows the heat can be brutal. Properly placed landscape elements can provide shade, which in turn reduces the heat flow into the home. Less heat flow into the home can help reduce energy bills.

Hillock said shade can reduce heat flow by as much as two-thirds. Likewise, shading roofs with tall, high-branching trees such as oaks, can help with cooling.

“While summer shade is desired to reduce cooling expenses, we also want to maximize winter sun,” he said. “To get the best of both worlds requires careful tree selection. Shade is good in the summer but can block the warming rays of the sun in the winter months. Computer models devised by the U.S. Department of Energy show the proper placement of only three trees can save an average household between $100 and $250 in energy costs annually.”

Characteristics to look for include high branches to block summer sun, but permit winter sun, which strikes the house at a much lower angle. Open branching, such as that of the Kentucky coffeetree, allows for a more open winter canopy and allows greater winter sun penetration.

Homeowners also may want to consider the timing of leaf drop. Ideally, look for trees that drop leaves between Oct. 15 and Nov. 15.

“When it comes to selecting trees that will be close to your house, homeowners may want to avoid trees with cone-shaped crowns, such as pin oaks and many evergreens because they provide significantly less shade in summer and block winter sunlight,” Hillock said. “Consider shading south and west facing walls, which capture a great deal of heat from the hot afternoon sun during those dog days of summer.”

He also indicated the importance of shading the air condition unit, which can increase its efficiency by as much as 10 percent.

Wind is another contingency when planning an energy conserving landscape. Your home can lose much more heat on cold, windy days than on cold, calm days. Well-placed trees and shrubs can intercept winter winds and reduce heat loss.

“I know there are days when it seems the wind is blowing from every direction at one time, but typically the coldest winds arrive from the north and northwest,” he said. “Therefore, a windbreak is best located along the north and west edge of your property.”

Foundation plantings are the plant materials placed along the perimeter of the home and impact the energy gain and loss from a home in a variety of ways. They act as insulation against wind, reducing air currents close to the home. They also create pockets of air that act to insulate the home. As with wind breaks, evergreens have a greater impact on energy savings than deciduous plants. Place plants so there will be at least a foot of space between full-grown plants and your home’s wall.

For more information regarding energy conservation and the landscape, check out OSU Fact Sheet HLA-6417: Landscaping for Energy Conservation at http://osufacts.okstate.edu.