Recommendations for hot
climate zones
Warm-humid zones
Climate and summary High rainfall and high humidity are associated with a low diurnal range and a of characteristics relatively high and even temperature throughout the year. Light winds and long
periods of still air. Radiation intensity high; large proportion diffused so strong sky glare. Rain usually in afternoon often accompanied by violent electric storms.
Problems and Uncomfortably hot, sticky conditions which require high air velocity past the requirements body to increase efficiency of sweat evaporation throughout the year. The
dominant characteristics required of buildings are openness and shading: they must be designed to provide continuous and efficient ventilati6n, and protection from sun, rain and insects. Structures may need to withstand hurricane velocity winds and in certain cases safe shelters may be necessary for the hurricane period. Termites can be a problem.
Response: general Layout and form : buildings separated and scattered with free spaces between them to utilise air flow. Individual structures should be freely elongated; rooms preferably single banked with access from open verandahs or galleries. It may be advantageous to raise buildings on stilts. Orientation: north and south for habitable rooms, but if buildings are in shade variation possible to provide maximum air flow. Orientation to reduce solar radiation most important with high rise buildings.
Rooms: should ideally have openings on both the windward and leeward sides. Heat and moisture producing areas should be isolated and separately ventilated.
Outdoor areas: as for buildings, they should be shaded; vegetation must not block free passage of air. Adequate storm water drainage must be provided.
Response: structure Windows and ventilation: openings should be large with inlets of similar size where wide spread of air is needed. Large sliding or folding \,'aIls and adjustable louvres commonly used. Screens, lattices, grills etc are useful to admit air flow and provide protection against glare. Flyscreens essential-reduce air flow so best installed away from windows, eg around verandah or balcony. Openings must be protected from radiation, glare, driving rain and noise.
Walls: have less thermal value than in any other zone. Lightweight construction of materials with low thermal capacity. Ifheight of walls is kept down it is easier to shade them and protect them from rain. Unshaded walls must be insulated and have a reflective outer surface.
Roof: pitched to shed rain and with wide overhang for protection against glare etc. Lightweight, low thermal capacity, ventilated double roof preferable but must be able to withstand strong winds RcBccti"vc roof co\'ering : ceiling well insulated and with reflective upper surface. Space between roof and ceilIng well proofed against insects, rodents etc.
Surfaces: roof and exposed walls should be reflective (light coloured). It is difficult, however, to maintain light coloured paints in this climate because of high humidity and fungal growth.
Note:
Tropical marine In warm-humid island zones the sun will be lower in sky so greater intensity of solar radiation on wall facing the equator. Extra care needed in protection of this wall. Winds more reliable but hurricanes present a hazard.
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Hot-dry zones
Climate and summary High intensity of direct solar radiation plus radiation reflected from ground.
of characteristics HIgh diurnal and annual temperate ranges.
Low humidity and low precipitation.
Sandy environment with dust stonns.
Climate generally healthier than those of wann-humid lands.
Problems and Uncomfortable conditions created by extremes ofheat and dryness. Flies, sand requirements and dust stonns are a nuisance. Buildings must be adapted to summer
conditions- basically a problem of protection from intense radiation from sun, ground and surrounding buildings.
Reduction of heat takes precedence over air movement during daytime. Measures must be taken to reduce glare and to prevent dust penetration.
Response: general Layout and fonn : compact planning for groups of buildings to provide mutual shading and minimum exposure. Enclosed, compactly planned and inward
, looking buildings most suitable: patios and courtyards advisable. For large buildings high, cubical and massive fonns are advantageous.
Orientation: larger dimensions and windows should face north and south. Worst orientation, west-east, can be used for non-habitable spaces to fonn a thennal barrier .
Rooms: can be deep, should ideally open on to patio or indoor courtyard. Heat producing areas should be isolated and separately ventilated.
Outdoor areas: must be enclosed, inward looking, contain plants, be cooled by water and be shaded for most of the day. Paved surfaces should be avoided wherever possible. Provision must be made for outdoor sleeping.
Response: structure Windows and ventilation: relatively small, particularly on outside walls, and must be shielded from direct radiation and glare. Ventilation during daytime must be kept to the minimum required for hygienic reasons; good ventilation required at night.
Walls : simplest solution is to follow tradition and use thickest suitable walls. Rooms used only in evenings can be of materials with low heat-retaining capacity which cool quickly after sunset.
Roof: solid and heat storing with a reflective upper surface-flat concrete roofs often'used. Water spray or pool on roof can be effective.
Double roof sometimes used: lower portion heavy with reflective upper surface, outer layer lightweight with highly reflective surface above and low emittance surface below; ventilated air space between the two layers.
Surfaces: whitewash is cheapest, simplest and most effective way of making outer surfaces reflective: needs to be frequently repainted. Can cause glare off walls-Iight brown colour sometimes used.
Note:
Maritime zones Maritime zones similar but higher humidity causes discomfort; humidity tends to reduce diurnal variations and moderate temperatures. Air movement required at times so high tennal capacity structure not as effective. Wind towers very effective in these zones, Ideal to have lightweight area utilising breeze for daytime use.
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Composite zones
Climate and summary Two or three distinct seasons; one similar to that of hot-dry deserts (usually of characteristics longest period), another to the wann-wet zones. Some places have a third
season, cool and dry with low humidity, wann sunny days and cold nights. Diurnal range large during dry seasons; small during wet period.
Radiation and direction of glare vary with seasons.
Problems and Complex climates from designer's point of view. Buildings must satisfy requirements conflicting needs ofhot-dry and wann-humid periods and must, in some places,
make provision fora cool or cold season. Where incompatible needs arise, length, duration and relative severity of seasons must be analysed to find balanced solution and most satisfactory compromise. The Mahoney Tables would be useful for assessing requirements: a study of local building traditions is also helpful.
Response: general Layout and fonn : with conflicting requirements different solutions may be equally appropriate. Layout should be moderately compact to provide mutual shading and shelter from wind in cold season but allow advantage to be takefiof prevailing breezes in humid period. Courtyard buildings are suitable, terraced buildings facing north and south may also be appropriate.
Orientation: toward north and south but prevailing breezes during humid period must be considered as well as radiation required in cold months.
Rooms: if double banked, adequate internal openings must be provided to ensure good air flow during humid period.
Outdoor spaces: courtyard most pleasant space for most of year if shaded during hot period and sunny during cool months; pergola with deciduous creeper can be solution: Provision for outdoor sleeping may be essential.
Response: structure Windows and ventilation: medium sized openings in opposite walls but with thick shutters to reduce flow of heat and dusty air during hot, dry season (opened in evenings) and cold air in cool season. Provision must be made for ventilation during these periods; simplest solution one high level and one low level opening. Wind towers are sometimes used with catcher opening covered during cold weather. Windows must be protected from radiation and glare (both from sky and ground) but shading undesirable in winter.
Walls: thick heavy walls are required for hot-dry and cold periods but as large openings are needed in outer walls, thennal capacity should be provided through heavy internal walls, floors and ceilings. In hot seasons walls should be shaded and surfaces exposed to sun should be light coloured. In cold period sun is required on walls.
Roof: heavy with reflective outer surface. Large projecting eaves advisable for shade and protection against glare and rain.
Surfaces: those exposed to the sun during the hot and wann seasons should be light coloured or of shiny metal. Some of the surfaces receiving sun during the cold (but not the hot) season should be absorptive.
Note: Upland (or highland) zones, although having more moderate temperatures, are Uplands dominated by strong solar radiation; adequate shading for windows and
external activities in summer therefore important. Roof very important as it receives greatest amount of radiation. Nights-can become cold and some heating may have to be provided for winter.
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.
Sub-tropical :
Mediterranean
Climate and summary Summers warm to hot and dry; winters cool to cold .with moderate rainfall. of characteristics Intensive solar radiation especially in summer. Variability of temperatures.
humidity and rainfall quite large depending on location, eg marine, continental or mountainous.
Diurnal range: large in continental locations, small in marine locations.
Problems and Buildings must be designed to provide protection from summer heat and from requirements cold and rain in winter. In continental locations summer heat and dust create
problems similar to those found in hot-dry zones, while in marine locations heat and humidity in summer require good ventilation. Condensation can be a problem in winter in marine locations. Dust can be a problem in summer, particularly in continental areas. Some heating in winter is usually necessary .
Response: general Layout and form : in continental areas the requirements a,re similar to those in hot dry lands but as climate is more moderate, spacing need not be quite so compact to allow for sun and light in winter. Courtyard plans suitable. In marine areas buildings on east-west axis with adequate spacing to allow for breeze penetration will be more appropriate.
Orientation: because of high intensity of solar radiation, windows should face north and south, but prevailing breezes must be considered in marine locations. Rooms: preferably single banked in marine areas; if double banked adequate provision must be made for good through air flow.
Outdoor spaces: courtyards for shade in summer and protection from cold winds in winter in continental locations. Shaded areas utilising breeze in marine areas, but protection against winter winds must be kept in mind.
Response: structure Windows and ventilation: in continental areas the requirements are similar to those in hot-dry lands but with cold winters sun would be welcome during this period. Medium sized openings are needed to ensure good air flow during summer and permit the penetration of sun in winter.
Walls: continental areas, as for hot-dry zones. In marine areas heat capacity is not as important but internal walls and floors could be heavy to store heat during winter while preventing the internal temperature from rising too much when sun is allowed to penetrate through windows.
Roof: sloping roof to shed rain; should provide shade for windows and protection from rain. Otherwise as for hot-dry zones.
Surfaces: wall and roof should be reflective (light coloured) where not shaded.
Note:
Sub-tropical humid Complex climate from the designer's point of view. Basically as for wann- humid zones, but provision must be made for the winter months which can be cold. Mahoney Tables would be useful for assessing basic requirements, which will obviously involve some compromise.
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