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Landscaping for Energy Savings

DEFINITION
CONSIDERATIONS
COMMERCIAL STATUS
IMPLEMENTATION ISSUES
GUIDELINES

  1. Shading
  2. Windbreaks
  3. Vines for Shading
  4. Arbors
  5. Absorbent and Reflective Materials

CSI Numbers:

029 500
073 100 to 076 100


DEFINITION:

“Energy conserving landscapes” reduce energy costs in a home during summer and winter. Ideally, the energy conserving landscape is also a water conserving landscape.


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 Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Trees Shade HVAC Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Windbreak Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Reflective Roof/Walls Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Paving Shaded Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Legend
Satisfactory Satisfactory
Satisfactory in most conditions Satisfactory in most conditions
Satisfactory in Limited Conditions Satisfactory in Limited Conditions
Unsatisfactory or Difficult Unsatisfactory or Difficult


COMMERCIAL STATUS

TECHNOLOGY:

Well developed but under-utilized.

SUPPLIERS:

Available, but generally not practiced.

COST:

The costs associated with implementing a landscape design that is energy conserving should not impact costs more than conventional landscapes.


IMPLEMENTATION ISSUES

FINANCING:

Available

PUBLIC ACCEPTANCE:

A landscape that is energy conserving is very appealing particularly since aesthetic enhancements are integral to any planned landscape design.

REGULATORY:

N/A


GUIDELINES

1.0 Shading

Trees are primary in an energy conserving landscape. Trees can have a canopy large enough to shade roofs, reducing cooling costs and increasing comfort.

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.

2.0 Windbreaks

The effective zone of protection for a windbreak can be 30 times the height of the trees. However, the maximum protection occurs within 5 – 7 times the tree height. For example, if the windbreak will be 25 feet tall, it should be placed from 125 to 175 feet from the house.

Characteristics of an effective windbreak

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.

3.0 Vines for Shading

When trees are young and not providing much shade, vines can be used to provide shading on walls and windows.

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.

4.0 Arbors

Arbors along the sides of the house, attached or detached, will similarly reduce temperatures as the air movement can pass through the arbor and be cooled by evaporation at the plant’s leaves. The shade created by the arbor is also beneficial. The arbor is a traditional cooling method used worldwide.

5.0 Absorbent and Reflective Materials

Groundcover and/or turf also has a cooling effect from evapotranspiration (the loss of water from the soil by evaporation and by the transpiration of the plants growing therein).

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.