A well-designed building shields its occupants from unpleasant outdoor conditions, such as excessive heat, cold, wind, and rain. The structure should also minimize energy consumption and maximize indoor comfort. In hot climates, either arid or humid, reducing heat and moisture gains are crucial factors in building design. Optimizing the thermal performance of buildings in hot climates must take into account the structure’s orientation and shape, along with construction designs and materials. In hot climates, a building should be energy efficient and provide year-round comfort to its occupants.
A structure's orientation greatly influences the impact of the sun and wind on the dwelling. Orienting the largest dimension of the building north and south can significantly reduce a building's solar exposure. The windows should face the prevailing wind, which will maximize cross-ventilation of the rooms. Typically, the north and west sides of the house will provide the most breeze and ventilation. Proper orientation of a building will provide occupants comfortable living spaces throughout the year and even under severe weather conditions.
The Building’s Shape
In hot climates, the courtyard design for buildings helps to minimize the solar radiation impact from the outside walls by creating a cool, shaded area within the building. It also gives the structure added safety and privacy. In the winter, on cooler nights, if the courtyard has a southern exposure, it can have passive heat gain. Always include movable shading devices in a courtyard for needed cover.
Room arrangement is also a consideration in hot climates. North facing rooms have good daylight most of the day and may require shading to prevent overheating. Consider putting non-livable spaces on the west side where the sun's impact is greatest. Rooms on the east side of the building have good morning solar energy but are cooler in the late afternoon. In hot climates, a room’s purpose is an important consideration in determining its placement in a structure.
Continuous Insulation in Hot Climate Building Design
Hot climate building design must have a continuous layer of insulation around the building's envelope. The envelope includes the walls, floors, roofs, windows, skylights, etc. It is critical that the air handler and ductwork also be within the home’s thermal envelope. Continuous insulation is an excellent option for protecting a building’s envelope. Continuous insulation creates a higher insulation value, decreases temperature variations within the structure and increases energy savings. A good choice for continuous insulation is Bautex Block.
Bautex Systems’ lightweight stay-in-place insulated concrete block provides continuous insulation. It absorbs and stores heat energy through thermal mass and provides an air barrier between the interior and exterior of the building. Commercial, institutional and residential buildings can use Bautex Block. Continuous insulation also solves the problem of thermal bridging. Thermal bridging occurs when part of a wall, like a stud, creates a path around the insulation for heat to escape. Bautex Wall System has a continuous R-value of R-14. Well within the range of recommended R-values in moderate to warmer climate zones R-12 to R-14. Architects and builders can use Bautex Block insulated concrete block to quickly and easily construct durable, noise-reducing, fire-rated, and storm-resistant buildings from a single integrated wall assembly.
Preventing the flow of heat through the foundation of a building is essential in designing an energy efficient structure. Concrete slabs represent the primary foundation type in buildings. Because concrete is a good conductor, the foundation is an area of significant energy loss, particularly around the edges where up to 80 percent of heat loss in a floor slab occurs. A proven method of preventing the energy loss is with slab edge insulation. A recent study found that the use of slab edge insulation can results in the energy savings on the order of 13 percent. In hot climates, the use of slab edge insulation along with heat absorbing materials like cement, stone, and adobe products, can contribute to an energy efficient building.
Windows provide a building with both natural lighting and ventilation. In hot climates, it is important to use small windows that minimize the heat gain, particularly on the west side of a building. The main windows of a building, for both light and ventilation, should face north and south. Ideally, these windows should have insulated shutters that can be closed in the day and opened up at night. Every effort should be made to shade all the windows. Particularly those windows facing west and east which can have nearly five times the solar heat gain than the north facing windows, and more than triple that of the south facing windows. Window placement in hot climate building design is key to managing natural light, ventilation, and heat gain.
Roofs in hot climates should reflect and release the sun's rays. Roofing made of highly reflective materials, like white metal roofing or white concrete tile roofing, work well to reflect the heat and make the building's occupants comfortable. For added shade, roofs in hot climates should also have wide overhangs, ideally three feet wide or wider. Hipped roofs are great in hot climates because they provide shade to all sides of a house.
Building in hot climates should be durable and energy efficient. Hot climate building designs should take into account the structure’s orientation, shape, and room arrangement. Continuous insulation, placement of windows and roofing materials are essential design factors in hot climates. The challenge of building in a hot climate is to create an energy efficient structure where occupants are comfortable year round.