Cooling Landscape Ideas Posted on May 22 2019

University of Vermont Extension
Department of Plant and Soil Science

Summer News Article

CREATING A COOLING LANDSCAPE

Dr. Leonard Perry, Extension Professor
University of Vermont

Landscaping can give your home “curb appeal,” but did you also know that it may keep your home cooler and reduce both summer and winter energy bills?  Proper landscape design, along with associated plant choices, can reduce energy consumption and cool your home.

Just as you can benefit from the shade of a tree on a hot summer day, so can your home.  Planting deciduous (those shedding leaves in fall) trees on the south and west sides of buildings provide shade in summer, and allow the winter sun to reach the building through the then bare branches.  Depending on location, shading the roof of a house can lower inside temperatures 8 to 10 degrees (F). Some good choices for northern New England are maples, oaks, and the less commonly used beeches and ash.

In the summer, beat the heat by planting trees to shade the roof, walls, and windows of your home.  Shading even 20 percent of the roof for an entire day significantly will reduce your energy costs.  The type of tree you plant will determine the amount of shade provided. Be careful not to plant too close to the house to avoid damage to the foundation or siding.  Keep mature height and spread in mind when planting near homes.  A common mistake is to plant too big a tree too close, only to have it cover the house in a few years.

The city of Akron (Ohio), using software and formulas developed for the tree industry, calculated the energy-saving value of two dozen trees in 2012.  Most cost effective, with average dollar benefit per tree, were pin oak ($60), silver maple ($61, not a good choice for many landscapes as it can be short-lived and drop many branches), Norway maple ($49, not recommended now as it is invasive in many areas), basswood or linden ($49), red maple ($39), honeylocust ($32), and red oak ($28).

Plant trees along the western and southern sides of your house, taking care to keep them away from power lines and other obstructions that may get in the way as they grow.  If you are just starting out, or just can plant one tree, choose the west side.  In the morning, the summer sun beats on the east side of buildings, but these aren’t heated significantly being cool from the night.  During midday, although the sun is from the south, it is high in the summer sky, so has less impact on south-facing walls.  In afternoon, especially between 3pm and 5pm or so, the sun is lower in the west, and the air is warmer, so there is a much greater need to shade the west side of a building.

If you use an air conditioner, planting a flowering tree or shrub near the unit not only improves aesthetics but can increase the life of the compressor. The shade reduces the strain on the unit caused by operating it for long periods of time.  Just make sure you don’t block the air intakes.  Instead of a tree or shrub, you could erect a trellis two to three feet away from the unit, which allows access, as well as good air circulation.  Train deciduous vines to grow up the trellis.  Some possibilities are clematis, akebia, and honeysuckle.

Vines also can be trained to grow up an arbor or porch to cool your home.  Vines grow quickly and are a good choice if you have limited ground space or want to start saving on your energy bills immediately.  In winter, trim back the vines to let in more sunlight.  Plant perennial vines like hops if you have a big trellis, or string coarse twine (like baling twine) up to the eaves. Hops, once established after the first year, will provide lots of cover quickly.  Other good vines are Dutchman’s pipe or trumpetcreeper, both of which can grow large enough to shade most of your home in as little as five years.

Ask the experts at your full-service garden center what they recommend for vines best for your area and situation.  Not all vines are a good choice for landscaping as some such as Boston ivy may damage paint, shingles, brick, or wood by retaining moisture, especially if they are growing right on a wall or side of building.  One way to avoid this is to attach a trellis to the side of the house and train the vines to climb that, and not the house.

Shrubs can be planted to form a living fence between your house and the sun. Shrubs also can be planted near sliding glass patio doors and windows to shade architectural features such as these, which transfer heat during the summer months.  Choose varieties that grow about six to eight feet tall, high enough to block the late afternoon sun.  Some examples are serviceberry, several dogwoods (shrubs not the small trees), forsythia (quick, vigorous), mockorange, and lilacs.  For all of these, check to make sure the cultivar you have chosen will have the height you need, and not be a dwarf variety, and allow them the room they need for spread.

For more information about these and other woody plant choices, order a copy of book Landscape Plants for Vermont from the Vermont Master Gardener program (www.uvm.edu/mastergardener).  Your local nursery or garden center also should have a large selection of trees, vines, and shrubs for your energy-saving landscape.  Or work with a landscape professional, and start saving energy dollars today!