North-Central Florida is extremely hot and humid for several months of the year, and temperatures frequently drop below freezing in the winter. These conditions pose a problem for keeping interior temperatures comfortable without the use of energy intensive HVAC systems.
The traditional methods for dealing with the heat and humidity utilized natural ventilation. These methods are at odds with the sealed and insulated envelopes required for efficient HVAC use, posing a dilemma for architects and builders. The five design principles of the Spectacular Vernacular make it possible to utilize both of these methods simultaneously.
The 5 Points Toward a Spectacular Vernacular
1: Double Skin
Exterior skin, fully operable and capable of opening to the exterior environment for ventilation.
Interior skin, insulated and sealed from the exterior environment, and conditioned with HVAC
2: Sunroom: Code Benefits
The HVAC-serviced space defined by the interior skin is the only part of the house that counts as interior space under the local building codes if the "interior skin" is constructed as an exterior wall assembly. So, the rest of the house, the lion's share of the spaces defined by the fully operable secondary skin, are classified as a sunroom under the local code, making the exterior operable skin an ancillary structure with fewer restrictions in design.
3: Variable Program:
The house's three large spaces receive variable programming based on the whims of the occupants throughout the seasons. This lack of specificity was all but eradicated by the modernists and their tenet that form must follow function. Most functions are comfortable in a variety of forms. This is a lesson that can be learned just as easily from a Cracker House as from a Palladian Villa.
4: Follow the Climate:
North Central Florida is extremely hot and humid for several months of the year, and because of the humidity, sun shading is not enough to offer respite from the climate. During the hottest summer months, the wind is also little help; with average speeds clocking a mere 5-6mph, there just isn't a lot of wind to replace the hot, sticky air in a semi-enclosed space. Added complications are the cold winter temperatures, frequently freezing at night during a few months of the year. A low-energy house will need to respond to both of these uncomfortable, possibly dangerous conditions.
The operable skin of the Spectacular Vernacular home is designed with the local, seasonal climatic conditions in mind. Block cold winds from the north in the winter, channel winds when appropriate in the summers, and allow complete access to air currents during spring and summer months, while providing ample shade.
5: Displacement Ventilation / “Hot Tin Roof”
When the wind fails to provide ample air-flow to relieve interior temperatures, the combination of a “hot tin roof” and a crawl-space can create relatively cool breezes in properly configured interiors. On the southern end of the house, a corrugated metal-wrapped wall and roof assembly is finished on the interior with insulated panels. The plenum space between the outer metal cladding and the interior insulated wall panels creates a hot-space baked by the Florida sun that can reach nearly 200° F. This hot-space is vented at the bottom and top, creating airflow as the air in the cavity heats and rises. Simultaneously, cool air from a shaded crawl space below is sucked into the interior through porous wood plank flooring. Casement windows in the clerestory vent the hot air out of the interior over head. Small fans in the clerestory can facilitate the process if necessary. The vent configuration can also be modified to heat the interior in cold winter months.