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CONSIDERATIONS:
It is possible to achieve as much as a 30% reduction in cooling and heating costs through careful landscape planning. Landscaping can reduce direct sun from striking and heating up building surfaces. It can prevent reflected light carrying heat into a house from the ground or other surfaces. By reducing wind velocity, an energy conserving landscape slows air leakage in a house. Additionally, the shade created by trees and the effect of grass and shrubs will reduce air temperatures adjoining the house and provide evaporative cooling.
The use of dense tree and shrub plantings on the west and northwest sides of a home will block the summer setting sun. This is the most effective landscape planting strategy. Additional considerations include the use of deciduous trees on the south side of the house that will admit summer sun; evergreen plantings on the north side will slow cold winter winds; constructing a natural planted channel to funnel summer cooling breezes into the house.
Carefully evaluate existing plants at a building site to identify those that can play a role in an energy conserving landscape. The established plants will require less effort to maintain and will generally be of a larger size and better established than new plantings.
Commercial Status |
Implementation Issues |
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Trees Shade Building | |||||||
Trees Shade HVAC | |||||||
Windbreak | |||||||
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Paving Shaded |
Legend | |
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Satisfactory |
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Satisfactory in most conditions |
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Satisfactory in Limited Conditions |
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Unsatisfactory or Difficult |
GUIDELINES
The best locations for deciduous trees are on the south and east sides of a house. When these trees drop their leaves in the winter, sunlight can reach the house to help in heating the home. Note: Even without leaves, trees can block as much as 60% of the sun, making placement of trees critical to effectiveness.
Evergreen trees on the north and west sides afford the best protection from the setting summer sun and cold winter winds.
If large trees need to be planted, it is best to select trees that have a moderate growth rate rather than fast growing varieties. Moderate growing varieties are sturdier against storm damage and generally more resistant to insects and disease.
A tree that will reach a medium to large size should be located 15 to 20 feet from the side of a house and 12 to 15 feet from the corner. Smaller trees can be planted closer to a house and shade walls and windows.
Shrubs or small trees can be used to shade split air conditioning or heat pump equipment that sits outside. This will improve the performance of the equipment. For good airflow and access, plants should not be closer than 3 feet to the compressor.
Evergreen shrubs and small trees can be planted as a solid wall at least four to five feet away from the north side and provide a windbreak. However, it is better to have dense plantings further away so air movement can occur during the summer.
The windbreak extends to the ground.
Foliage density on the windward side is optimally 60%.
Two to three rows of evergreen trees in staggered order should be used. If using deciduous trees, there should be five to six rows.
The length of a windbreak should be 11.5 times the mature width of the stand of trees.
The tree heights within the windbreak should be varied.
Some vines such as English Ivy will cling to any wall surface. This can harm wood surfaces.
Trellises placed close to the walls can be used to support vine growth without touching the walls.
Using vines which lose foliage in the winter can be used for summer shading as long as vine stems do not significantly block winter sun.
Evergreen vines will shade walls in the summer and reduce the effects of cold winds in the winter.
The temperature above a groundcover will be 10 to 15 degrees cooler than above a heat absorbent material such as asphalt or a reflective material such as light colored gravel or rock.
A heat absorbent material like asphalt will also continue to radiate heat after the sun has set. It is best to either minimize the use of heat absorbent and reflective materials near a house and/or shade them from any direct sun.
RESOURCES
PROFESSIONAL ASSISTANCE
Texas Assn. of Landscape Contractors
3001 LBJ Frwy., Suite 105
Dallas, Texas 75234
(214) 241-1399
Texas Board of Architectural Examiners
8213 Shoal Creek Blvd.
Austin, Texas 78758
(512)458-4126
(for list of registered
Landscape Architects)
Xeriscape Garden Club
P.O. Box 5502
Austin, TX 78763
(maintains a list of professionals)
Chuck Sims
(512) 331-9630
City of Austin
Parks and Recreation Department
200 South Lamar Blvd.
Austin, TX 78704
(512)499-6700
TreeFolks
P.O. Box 704
Austin, Texas 78767
Mary Mcarthy
(512) 443-5323
Austin ReLeaf
P.O. Box 704
Austin, TX 78767
(512) 433-5323
State Energy Conservation Office
221 E. 11th St., Suite 200
Austin, TX 78701
(512) 463-1931
City of Austin Xeriscape Program
Dick Peterson
City of Austin Water Conservaton Program
P.O. Box 1088
Austin, TX 78767
(512) 499-2199
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Sustainable Building Sourcebook web version copyright Sustainable Sources 1994-1999.
This file last updated on Thursday, November 18, 1999