Plant a Deciduous Shade Tree

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Quick Facts Affordability Cost Savings CO2 Reduction		Well-designed landscaping can minimize summer heat gain in your home, reducing 20% to 100% of your cooling needs. Planting a deciduous shade tree on the southwest or southeast side of your house will help reduce your cooling needs and help maintain a comfortable indoor air temperature. Affordability Plants vary in the care they require. Ask at your local garden shop or landscape company for plants and trees that grow well in your region, but do not require great amounts of additional water and other resources. Cost savings Well-designed landscaping can reduce cooling costs by 20% or even up to 100% in areas without significant cooling demands. Health & comfort A well-placed deciduous tree can help keep your home cool in summer. After the leaves drop in autumn, sunlight will warm your home through south and west-facing windows during the colder months. Environmental considerations Trees deliver more than cost savings – they are important carbon sinks, helping to reduce global climate change. Select varieties that require minimal care and water, and can withstand local weather extremes. Fruit or nut trees that produce in your area are great choices, providing you with local food as well as shade.

What you need to know

• In addition to providing shade, plants and trees also cool by evapotranspiration, which is heat removal due to the evaporation of water from the leaves.
• Planting trees and shrubs to shade the outdoor portion of your home’s air conditioner could increase its efficiency by as much as 10%. Be careful not to obstruct airflow around the unit.
• If you are paving along the south side of your home, use only permeable pavement or permeable light-coloured concrete. This can increase heat radiation on your windows and walls. Use bushes and plants to shade pavement and rock features from the house.
• Ask at your local nursery for plants best-suited to your area and needs or use Evergreen's guide to native plants to help in your decision making.
• Read our Shade Your Windows tip for additional ways to create shade and keep your home cool in summer.

Vines

• In apartments or condos without lawns, you can achieve cooling effects using grasses, vines or small shrubs grown in window boxes. Clematis and wisteria vines grow well in containers.
• Vines grown on trellises can shade windows, a patio or an entire side of a home. Choose vines that also provide food, like grapes, domesticated blackberry, kiwi or runner beans.
• Set trellises at least 15 centimetres away from the wall to allow air to circulate. Prevent vines from attaching to your house and damaging the exterior.
• Consider creating a "Living Wall" instead of planting vines and shrubs, to achieve insulating effects.

Shrubs

• If you plant shrubs, choose varieties that only grow to a maximum height or are easy to prune, so they won’t eventually block light or winter sun.
• Shrubs and other groundcover plants will accelerate the cooling benefits where you have slow-growing trees or trees with high branches.

Trees

• To choose the right shade tree for your home, consider the eventual height, growth rate, branch spread and tree shape.
• Be aware of seasonal sunshine patterns. When selecting a planting site for a tree, note the size and direction of summer shadows to determine where your tree will shade.
• Do not plant trees directly to the south of your home. Instead, plant on the southwest or southeast exposures. In the winter, even the bare branches of mature deciduous trees can reduce the amount of sun reaching your south-facing windows, limiting natural heat and light gain.
• It can be helpful to have a professional determine the best location for your tree to maximize energy efficiency.
• Slow-growing trees tend to live longer than fast-growing trees and are less susceptible to breakage or drought because they have stronger branches and deeper roots.
• Be sure your planting sites are safe, above ground and below. Do not plant trees under utility lines or other obstructions. Underground, avoid buried utilities, sewer lines and building foundations. Call your local utility before you dig to locate any underground obstructions.
• When planting close to the home, take care to protect your drainage system piping. Roots of trees will become larger and could potentially damage the drainage system. Avoid planting bamboo near the home as the root system can create damage – plant it in a box.
• Shading your roof, or using a green roof, will increase cooling effects even more than shading windows. Place trees that grow tall, with widespread branches, on the southwest or southeast sides of the house to shade the roof when they reach full height. Trees with branches that spread lower to the ground are best on western exposures to provide shade from the lower angle afternoon sun.

FAQ

How long will it take before I am getting cooling benefits from a tree?
Different tree species grow at different rates. Climate and rainfall also affect tree growth. As a guide, a well-located 2-2.5 m (6-8 ft.) deciduous tree will begin shading windows in its first year and will often grow enough to shade the roof in five to 10 years.

Why are deciduous trees better than evergreens?
Deciduous trees planted outside southeast, southwest and western exposures provide shade during the warm summer months, then drop their leaves, letting light and heat in through the windows in winter. In some situations, evergreens will work well, particularly in windy locations, as they tend to be more resilient. However, heating in winter is more of a concern in B.C. than cooling in summer, so ensure you don’t plant evergreens where they will block winter sunlight from warming south and west windows.

Should I plant shrubs and other plants right against the house to get the best cooling effects?
No. Placing vegetation too close to your house can trap heat and make the air around your house even warmer. A dense line of shrubs or trees can block the flow of air through or around them. Instead, plant trees and shrubs where they will direct breezes. Shrubbery planted a few feet away from the house will provide extra shade without obstructing air currents.