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.