Retrofitting Existing Landscapes To Conserve Energy
by Dr. Robert Black, Consumer Horticultural Specialist

Retrofitting refers to modifications made to existing homes to improve heat loss and gain through insulation, weatherstripping, etc. Retrofitting can also be applied to the addition of landscape materials to control the climate of your home.

As with a new constructed home you must first determine the orientation of your home in relation to the sun or street. The amount of retrofitting will vary with orientation. Houses with the long axis oriented north-south will require more extensive plantings for shade than houses with an east-west orientation. Provide shading as much as possible on east and west walls, since these will experience the greatest impact from the sun's rays.

Trees effectively provide needed shade. With proper pruning, trees may also have a favorable effect on air circulation. Proper placement of trees relates to the location of the sun during the time of high heat load. Latitude, time of day, and time of year are determinants for the location of the sun and for the sun's effect on shade direction.

Mass plantings of shrubs may direct or deflect wind direction. Shrubs may also provide shade to reduce glare and reflected radiation while the sun is low in the sky. Additional benefits may be derived from moderate reduction of noise and air pollution by using mass shrub and tree plantings. Skilled design avoids the problem of blocking needed air flow. Cold winter winds, however, can and should be deflected.

When space may not allow tree plantings for shade, vining plants may provide relief from solar radiation. Trained on a trellis or arbor, vines may provide a canopy similar to a tree canopy. Vines, however, do not require the ground space required by a tree. Of course, proper selection is essential to avoid excessive maintenance. The trellis or arbor should be placed to allow adequate air circulation.

Vegetated soil surfaces affect the air temperature in a favorable manner. Brick and concrete, on the other hand, reflect solar radiation and often cause discomfort from glare and heat. Asphalt absorbs solar radiation and re-emits the energy as long wave radiation. Surfaces which absorb more moisture, such as pine straw and wood chip mulch, reflect or re-emit very little radiation.

Concrete patios reflect and re-emit considerable amounts of solar radiation. A raised wooden deck is cooler because wood is a poor heat conductor and the raised design allows air to circulate underneath.

Driveways and walks are often concrete, brick or asphalt. Use of mulching materials, treated wood, or brick with interspersing ground cover will produce less heat build-up than large areas of hard, reflective surfaces.

Mulched areas and ground covers such as lily turf, mondo grass, ivy and dwarf confederate jasmine require less energy for maintenance than turf. When using turf, select a lawngrass most suitable to the site in order to reduce energy used for maintenance.

These passive energy conserving measures can decrease a homeowners dependence on air conditioning. Wise landscaping results in substantial savings to the homeowner in their monthly utility bills as well as helps reduce state and national energy consumption.