Plan your home and landscape to save energy
By Lloyd Thompson
WSU Chelan/Douglas County Master Gardener
What if I told you that you could save 25% on heating and cooling your house while doing nothing to, or in, the house? This isn’t anything new, requires no gadgets and can improve the curb appeal of your house while you save that 25%.
A well-designed energy saving landscape not only can add beauty to your home but also can reduce your heating and cooling costs. A well-placed tree, shrub, or vine can deliver effective shade, act as a windbreak, and reduce your energy bills. Carefully positioned trees can save up to 25% of the energy a typical household uses. While it works with older homes, it may be even better on new construction that incorporates the house’s design features to work with the landscaping.
In most of the United States, we have both a winter and summer season. The sun’s position changes with the seasons, and that change increases as you go north. The farther north you are, the lower the sun rises in the winter months.
For me, this means the sun’s rays strike the south side of our house longer in the winter than in the summer when it rises higher and is blocked by the eaves on our house. It can get warm enough on a sunny day to be too warm to sit in front of our glass slider, even when the temperature outside is near freezing. We have noticed this the most during January and early February, but by March the sun is rising higher and the sun strikes the windows for a shorter period each day.
Landscaping with deciduous trees and shrubs on southern exposures can make use of this by allowing the sunlight to reach the house by dropping their leaves in the fall. Evergreen trees would block the winter sun and you miss out on the extra heat and light reaching your house during the winter.
This thermal benefit can even be enhanced on new construction by careful planning and design. Wider eaves can shelter a home from hot summer sun while allowing it to reach the home during the winter because of the lower sun angle. Heat will “sink” into areas of your home, such as masonry walls, which allows the sun to warm up the thermal mass during the day and will continue to release the heat after the sun goes down.
The other side to this is that cold, winter winds are often from the northeast. While we are protected by the surrounding mountains from the worst of the winds, it can still be a substantial loss of heat from homes. This is where thoughtful use of evergreens can help break up the wind pattern and reduce the loss of heat by slowing the wind speed as it strikes the house.
Windbreaks are often designed with several rows of plants to maximize the efficiency at reducing the wind speed. Be careful while planning so you don’t plant flammable plants too close to the house. Washington Firewise USA practices to prevent wildfires can help to determine distances and what plants to use.
This is often reversed during the warmer months, when winds are from a more southwesterly direction. Hot, dry winds can cause a substantial loss of soil moisture and drying out of plants. Once-soft green leaves can become crunchy as the drying winds pull the plants’ moisture away. This is worse in some plants than others; some are better adapted to our area and have a leaf surface designed to withstand the loss of moisture. These plants are often ones selected for xeriscaping as a result.
Using these deciduous plants on the southern and westerly exposures will help ease the winds and can protect your plants from drying out. If properly designed and spaced, you can substantially reduce the cost of cooling your house by keeping hot winds and direct sun away. The evaporation of plant moisture and the reduced direct sunlight striking the house can reduce cooling costs 25% or more.
There’s not enough room to talk about everything that will help in planning a home and landscape to save energy. Many ideas were developed long ago and forgotten over time. Houses built prior to the use of widespread air conditioning incorporated covered porches and windows that drew cooler air in at night. The plants and trees were selected and planted for more than just the esthetics they brought to a design. Closing blinds or curtains during hot days or cold nights can make a big difference.
Careful, well-thought-out homes and landscapes can make a substantial difference in the cost of heating and cooling, not to mention the enjoyment of a well-designed landscape. For detailed more information, check out the energy efficient landscaping at energy.gov/energysaver.