cooling for hot-dry climates

Most hot dry climates – south of USA, parts of Australia, most of North Africa, Middle East, Iran, etc. – have very hot and dry summers, with diurnal differences of temperatures that may vary a lot… Cooling needs are typically higher than summer heating needs, but heating needs are also significant and should be considered in the home design and landscaping.

Cooling methods for Hot Dry Climates

As with other hot climates... 1) home orientation, 2) shade and 3) cross ventilation are key cooling elements. Other more specific elements include 4) insulation and 5) evaporative cooling (swamp coolers, water ponds and pools and other means).

Overhangs, well sized and located windows, proper landscape, and a combination of low thermal construction materials with high thermal ones, are also important elements.

Air conditioning can be used, but it is expensive, and demands a proper approach to minimize the bills.

Air conditioning in hot dry climates

Natural cooling (through cross ventilation), swamp coolers and other evaporative cooling methods are good and cheap alternatives to air conditioning in hot-dry climates. Ceiling fans should also be considered in alternative to air conditioning, and as complement to other natural cooling strategies.

Solutions involving air conditioning should only be considered in well sealed homes, with high insulation levels and small windows, in regions where breezes and diurnal temperatures differences are very small. In this case, high levels of insulation and sealing will reduce the air conditioning needs and energy bills.

Home orientation

Home orientation should provide good cross ventilation (through windows opened to the prevailing breezes) without excluding sun protection goals (in hot weather periods) and sun heating (in winter)...

Shade, vegetation, overhangs

Shade is an important elements to avoid unwanted heat gains, but trees (deciduous) and other vegetation shouldn’t block the winter sun.

Overhangs are key elements to shade windows and walls from the summer sun, without blocking it when it is lower, in winter.

Cross ventilation

Well located windows, open to the prevailing breezes – namely in climates with reasonable diurnal temperature differences – are a key element of natural cooling (through ventilation).

See:
Cooling and Windows
Cooling, Cross Ventilation and Window Fans

Evaporative cooling

Swamp coolers can work at a small price of air conditioning and are very effective in hot dry climates. But there are other methods based in the cooling effects of water (evaporative cooling) like water ponds.

Insulation

High levels of wall, ceiling and roof insulation are important in hot dry climates. Insulation will reduce undesired heat gains (and cool losses) in hot weather conditions, and will also help to maintain more balanced temperatures in winter (including smaller heat losses during the winter).

Windows

Windows are a key element for cross ventilation. They should be positioned to get the prevailing winds.

However, they shouldn’t be too large, to avoid unwanted heat gains or energy losses. For the same reasons, they should be properly sealed and shaded (through overhangs or vegetation).

Windows on the east and west side of the house should also be protected by awnings or vegetation, to avoid low sun striking and glare.

Walls and floor materials

Walls embodying materials with high thermal mass - materials that hold heat well, and cool slowly - are common in climates with cold winters. If the winters aren't cold enough, low thermal mass solutions can be more advantageous (walls will release the heat they have accumulated during the hotter hours much more quickly).

See: Thermal Mass Basics