Solar energy is absorbed through a house’s windows and roof. This can increase the air conditioners work load in the summer months and reduce the heating load in the winter months.
A Small Investment that Guarantees Sizable Returns
Homeowners are going to great lengths to conserve energy. They are investing in expensive energy efficient appliances, switching to alternative green energy sources like solar power and wind power. A simple and inexpensive energy saving technique that is being overlooked is the natural energy saving ability of shade trees. Air conditioning bills can be reduced by as much as 25 percent in a house that utilizes tree shading.
Trees Can Block the Sun’s Light Energy
By planting trees on the southeast, south and southwest of a house, the summer sun can be effectively blocked from transferring its energy into a
home. A study conducted in Sacramento, California showed that trees planted on the north side of a house increased summer electricity use (5.2 percent), while trees planted on the south and east sides of the home decreased summer electricity usage (1.5 percent).
The study’s results also showed that the London plane tree cuts summer emissions from electricity usage by 31 percent over 100 years. Trees planted to cast shade on pavement hinder the pavements ability to absorb, reflect and radiate heat. Deciduous trees with high spreading crowns work best when planted on the south side of a home and a shorter tree planted on the west to block the setting sun’s rays. During the winter deciduous trees lose their leaves in the winter allowing the sun’s light energy to heat a home. Shading an outdoor air conditioning unit can increase its efficiency by 10 percent.
Trees Slow Down Cold Winter Winds
Cold winter winds create lowered wind chill near homes. The chilly drafts can enter the home through small crevices reducing temperatures in the home. Cold winds can also cause heat loss by coming in contact with the outside of a home, drawing heat away. Planting trees can break the wind by 30 times the height of the wind break. Plant wind breaks a distance of two to five times their mature height from the house. Evergreen trees such as junipers, spruces and firs planted on the north and northwest of the home can provide effective wind breaking.
Trees Cool the Air Around Them
Trees can cool the surrounding air using the heat energy to evaporate water off the leaves surfaces. This process is called evapotranspiration. Evapotranspiration to trees is like sweating to humans. It can drop the air temperature by as much as 9 F. The cooler air produced then drops lower to the ground (hot air rises), this combined with the tree’s effect of blocking out solar radiation can drop temperatures under trees as much as 25 F.
Useful Tree Planting Tips
- Take into consideration the mature tree size and crown when choosing a tree to plant.
- A mature tree can interfere with electrical power lines, or a home’s foundation and driveway, so choose locations cautiously.
- If wildfires are a concern homeowners can contact local forestry departments for advice.
References
EERE Consumer’s Guide: Landscape Shading
USDA Forest Service, Pacific Northwest Research Station. “California Study Shows Shade Trees Reduce Summertime Electricity Use.” [ScienceDaily](https://<http//www.sciencedaily.com¬ /releases/2009/01/090105150831.htm) 7 January 2009. 27 January 2009
