Building Science

Designing Energy Efficient Buildings in Hot Climates

hot climate building design

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. 

Building Orientation

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

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.

Flooring

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

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.

Roofing

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.