Energy is the amount of work a system has to do to be active. It takes electricity to make sure we have lighting, heating and air conditioning. More energy is used in urban settings, where buildings, streets and paved surfaces store heat from the sun. One way to save energy is to plant trees and other vegetation around homes and buildings. Deciduous trees, or trees that shed their leaves every year, provide shading in the summer, which reduces the temperature and, therefore, air-conditioning costs. When the trees are bare during winter, they allow the sun to warm the house and reduce heating bills. Evergreen trees can block cold winter winds and save on heating costs.
Did you know?
- Trees properly placed around buildings can reduce air conditioning needs by 30 percent and save 20-50 percent in energy used for heating.
- The net cooling effect of a young, healthy tree is equivalent to 10 room-size air conditioners operating 20 hours a day.
- A mature tree can reduce peak summer temperatures by 2° to 9° Fahrenheit. 
- 100 million mature trees growing around residences in the U.S. can save about $2 billion annually in energy costs.
References U.S. Forest Service. Northeastern Area Home. Spotlight. Homeowner Resources. http://www.na.fs.fed.us/ (accessed June 4, 2013).  U.S. department of Agriculture  Environmental Protection Agency http://www.epa.gov/heatisld/strategies/vegetation.html (accessed June 4, 2013).  U.S. Department of Agriculture. Forests on the Edge. Sustaining Urban Trees and Forests. http://www.fs.fed.us/openspace/fote/reports/nrs-62_sustaining_americas_urban.pdf (accessed June 5, 2013).