South Florida is sunny, humid, and typically has outdoor air temperatures within 15 degrees of your indoor temperature set point.
That means the two biggest energy consumption and energy demand drivers, (those items that increase your energy bill), which carry a higher percentage of the total energy costs in the tropical climate of South Florida are;
- (1.) Radiant heat gain through a building’s windows
- (2.) Conditioning of outside air
(1.) Out of the different components of a building envelope, radiant heat gain typically has the largest impact on cooling load, AC equipment capacity, and thermal comfort.
Conductive heat gain through the building skin is driven by two factors, (assuming the building surface area is fixed in the design);
- The overall heat transfer coefficient of the building assemblies
- The temperature difference between the outdoor air and the indoor air
In South Florida, the temperature difference is relatively small when compared to other climates, where temperatures range from below 0F to above 95F. Meaning that for a code compliant South Florida building, you can spend less money on insulation with high R-values and assemblies with low U-values and more on the performance characteristics of your glazing and window assemblies. Lowering the window-wall ratio should also be considered. A smaller surface area of glazed openings can reduce the cooling load of a building as well as reduce the cost of glazing.
(2.) Whether brought in intentionally or leaked in via infiltration, outside air in South Florida, on an annual basis, has a higher average specific heat than other climate zones in the continental US. This means it costs more money annually to condition and dehumidify this air than it would in other parts of the country.
Using demand control ventilation, or DCV, can reduce the total volume of outside air that is conditioned per year by reducing the outside air intake when a building’s occupancy levels are low.
Using air-to-air energy recovery devices, if controlled and designed properly, can also be a good strategy to reduce the energy costs associated with conditioning a building’s outside air.
Considering these two South Florida energy efficiency killers when designing a new building can reduce energy consumption, energy demand, and lower the required AC equipment capacities resulting in a lower first cost.