Lots of people are still somewhat ambivalent about the importance of trees.
but luckily these people are running around with chainsaws, and even more fortunate is that forward looking people, both businesses and people, are looking forward for a better green future, where the importance of trees to our ecology are both celebrated and promoted. One such example is TD Bank who puts the money where their mouth is by funding tree preserves regularly, and not just for the PR benefits…
And there are many more businesses as well, like utilities, water management, environmental redevelopers and even the average homeowner. Yes, that’s correct, a good chunk of the trees planted each year are for urban and suburban landscaping purposes, and not always for the cosmetic effects.
When planted in the right location in your yard, trees can play a big role in smart energy living. The green building industry, the renewable energy industry, planners, home owners and developers are not yet taking full advantage of trees as an effective way to reduce energy use. Strategically planted trees can take advantage of both winter and summer sunlight to reduce overall annual energy use. In places with a cold-weather climate with more days requiring heating than cooling, using trees to achieve energy conservation is complex. Many factors have to be considered, such as your home’s orientation, window size, placement, space and efficiency. By providing shade and serving as windbreaks, trees contribute to both energy savings and energy costs.
During the summer of 2007, the Denver-based Institute for Environmental Solutions conducted The Tree Project, a study of trees in Golden that characterized the effect of trees on building energy use. The energy study analyzed the impact of specific tree species and planting locations on building energy consumption. Building, tree and solar data were combined, and energy use and carbon emissions were modeled using DesignBuilder, a state-of-the-art software tool. The study found that in many cases, trees had not been properly located around buildings for optimal energy conservation and often led to increased energy consumption because a tree blocked warming winter sun.
Here are some of the findings from the study:
• Trees’ impact on a building’s energy use can be both positive and negative.
• The amount of energy saved depends primarily on the building’s orientation, tree cover and windows.
• Trees were more detrimental for heating than they were beneficial for cooling, with a net increase in energy demand due to tree shading.
• In terms of economic cost and power plant greenhouse gas emissions, tree presence was a net benefit. This is due to the difference between summer and winter energy in market value and carbon intensity.
The results of the study suggest that trees in Golden cause more energy to be used for heating in the winter, overshadowing the energy they save on air conditioning in the summer. If trees were planted more strategically for energy efficiency, they would reduce wintertime heating bills and improve homes’ energy efficiency.
PLANTING THE RIGHT TREE IN THE RIGHT SPOT
Properly locating trees is essential to optimizing environmental improvement. To plant a tree for energy conservation, plant it first to shade the west side of your home in the hot summer afternoon. The next best spot is to shade the east side and then the west and east corners. Plant a large tree with big leaves and dense foliage, such as a Kentucky coffee tree, green ash, white ash, western catalpa, little leaf linden or white oak.
However, if you have a large evergreen tree shading the south side of your home (which may be increasing your heating needs), don’t despair! It is providing other environmental benefits that should not be overlooked. One tree can reduce storm water runoff, improve air quality and sequester, or take up, carbon dioxide – a greenhouse gas that has a significant impact on climate change.
Trees provide indirect environmental benefits for which they rarely get credit. By reducing energy demand, trees also reduce power plant water use and carbon emissions. Trees we found around different types of buildings in Golden saved $23 per building on its electric bill and 196 pounds of carbon from being emitted.
Desirée Thorp is a research associate at the Institute for Environmental Solutions. Contact Desirée at [email protected] or (303) 388-5211. Photo by Jeffree Benet.