The conversation around sustainability often centers on the products involved – solar panels, LED lighting, low-flow plumbing fixtures and materials made using recycled content.
While these all are good things, they are geared to a “retrofit” market, useful for updating existing buildings. With new construction, however, we can influence the energy performance of a building through “passive solar design” long before any of these systems or products are added. Looking specifically at Florida’s hot, humid climate, elements of design to be considered are shading, massing, cross ventilation, and daylighting.
Every Floridian knows the value of shade, and this applies to our built environment, as well. Expansive overhangs protect your home in the same manner a wide-brimmed hat protects your face, neck and shoulders. We typically strive for a 1:1 ratio: the vertical height of a window matching or exceeding the horizontal length of the overhang shading it. This concept also can be applied to waterfront homes that are required to be elevated; when possible, we prefer to elevate the home enough that the ground level space becomes an outdoor living space shaded by the home above.
The massing of a building also can influence its energy performance. If separated into smaller volumes and spread apart, a greater amount of airflow is able to circulate between and around the volumes. This then creates a few design opportunities: exterior spaces between the volumes that benefit from the increased airflow; spaces that likely are shaded by the expansive overhangs of the volumes surrounding them; and a reduced amount of square footage that requires air conditioning.
Cross ventilation and daylight harvesting are terms often used in sustainability, but their relationship to each other is not always addressed. Cross ventilation relies on windows that are placed opposite each other, resulting in narrower building forms and natural airflow. This gives more rooms exterior walls and windows, which also means more available daylight in these spaces, requiring less power to light.
Passive design is an integrative process that effectively harnesses the environment, creating comfortable spaces, leaving a small energy footprint, and greatly reducing energy costs.