Microclimate Modifications For Energy Conservation
by Dr. Robert Black, Consumer Horticultural Specialist

Florida has a hot humid climate. Daytime temperatures can be above 90°F for seven months each year and humidity, at the same time, up to 50-70%. Only about one fourth of the year's climate is naturally comfortable. During a small portion of the year, particularly in north Florida, temperatures are too cool for comfort.

Generally, wind is an asset for a hot, humid region. Wind aids good air circulation which reduces buildup of heat and humidity. Besides the need to provide for adequate air circulation, there is a need for blocking solar radiation in order to reduce heat buildup. Two factors are essential for a comfortable microclimate in Florida: 1) air movement for evaporation and cooling and 2) shade for reduction of surface temperature and heat buildup.

The idea of using landscaping to reduce the effects of a harsh climate is not new, although the idea is referred to by a new term, microclimate modification. Today's high cost of energy makes it more important than ever to take a new look at using nature to reduce these energy costs. Nearly one fourth of energy consumed in Florida is for residential use and nearly 30% of that energy could be saved through passive energy conservation measures.

Options available to the homeowner for incorporating energy conserving measures into residential landscape fall into two categories: new construction and modifying or retrofitting existing homes to conserve energy.

Prior to construction, homeowners should try to select a lot with overhead canopy of trees if possible. Positioning a house to preserve and use shade from existing shrubs and trees will save the energy used for removing vegetation, selecting and planting new shrubs and trees and waiting for new plants to grow large enough to provide effective shade.

The orientation, or the way the house is positioned in relation to the angle of the sun, is the first factor to consider when modifying the microclimate. If the long axis of the house runs north and south, the surface of long east and west walls will receive solar radiation. An east and west axis will expose only the narrow end walls to the hot Florida sun.

Color of roof and walls will effect the amount of energy to cool or heat a house. Houses with light colored paint and shingles cost less to cool and slightly more to heat than a similar house with dark colored paint and shingles. The savings in cooling the house with the light colored paint and shingles is far greater than the increased heating costs.

Except when a screen is designed to divert cold winter wind, screening and fencing in Florida should not block air flow. In a hot,humid climate, good air circulation is essential to evaporation and related cooling. Solid structures block the needed air flow, deflecting breezes away from the residence. Open fence design, particularly where there is some clearance at the bottom, allows cooling breezes to pass through. Vegetative screening may also block air movement. Thinning out dense growth and trimming lower branches will promote natural cooling.

Through proper planning before construction, the need for retrofitting should be minimized.