We all know that planting trees improves our air quality, protects our watersheds, prevents erosion, and improves our lives in many ways. And now a study by the Pacific Northwest Research Station titled ‘The Value of Shade: Estimating the Effect of Urban Trees on Summertime Electricity Use’ documents exactly how they can save money….your money, taxpayers dollars, and postpone the need for more utility facilities. The study says that trees placed on the west and south faces of a house in a hot area of California can cut back a homeowner’s summertime electric bill by about $25 annually. Not impressed? Just multiply the small change with the number of houses in California. The numbers assume significance.
“Everyone knows that shade trees cool a house. No one is going to get a Nobel Prize for that conclusion,” says study co-author Geoffrey Donovan. “But this study gets at the details: Where should a tree be placed to get the most benefits? And how exactly do shade trees impact our carbon footprint?”
THE CONCLUSIONS OF THE STUDY WERE ::
- Placement of a tree is central to energy savings. The amount of the savings depends on the location of the tree.
- Trees planted within 40 feet of the south side or within 60 feet of the west side of the house will generate about the same amount of energy savings. This is because of the way shadows fall at different times of the day.
- Tree cover on the east side of a house has no effect on electricity use.
- A tree planted on the west side of a house can reduce net carbon emissions from summertime electricity use by 30 percent over a 100-year period.
It’s great to see the utility companies get involved in reducing electric use rather than building out new facilities:
In 2007, the Sacramento Municipal Utility District gave its customers about 16,000 free trees (at a cost of $85.00 a tree). The district will recoup this investment in 26 years provided trees are planted on the west side of a house.
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