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Climate and Architecture. Geog310 Urban Climatology.
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Climate and Architecture Geog310 Urban Climatology
Shelter with food, is one of mainstays of human life on earth. The nature of shelter required largely depends on the conditions of the environment, with the climate providing one base that determines the type needed (in harmonic with environment).
Climate Classifications • Genetic classification: based on the causes (air masses, atmospheric circulation) • Empirical classification: based on the results (temperature and precipitation, or vegetation patterns)
Koppen’s Classification Categories • Tropical (A): tropical wet (Af), tropical Monsoon (Am), and tropical wet and dry (Aw or Savanna). • Mesothermal (C): humid subtropical (Cf), Mediterranean (Cs), Mild humid subtropical dry winter (Cw) • Microthermal (D): humid continental and subarctic • Polar (E) • Highland (H) • Desert (B)
Climate and primitive constructions 1. In hot-wet tropics: latitudes 10°-15° from equator, mainly developing countries, 40% population lives in the belt. Small annual variation of temp, intense solar radiation, high humidity, and heavy rainfall. House should provide maximum ventilation and shades, roofs must be waterproof, walls movable. House often stilted to prevent frequent flooding near rivers that connect to outside world (or catch sea breeze in island), movable shutters (or porous walls). Materials have little or no heat storage capacity.
In tropical deserts (40°C daytime, and 10-15°C at night), intense solar radiation and heat during the day and low temperatures at night. Mud and straw are the basic materials. High heat capacity of these materials help maintain even temp in the building; thick walls with minimum window space. Grouped dwellings in dry area are often built close together for maximum shade (narrow streets in many Arab communities). Valleys are parallel to prevailing winds (minimize wind exposure), shaded side walk, short walking distance, courtyard with greenery, compact geometry, use high albedo materials as building surfaces. Dense and substantial thickness walls release heat during night, block sun during day, indoor temp lag behind outdoor.
Polar region, Inuit Igloo: hemispheric shape minimizes hear loss by providing maximum volume with a minimum of surface area and effectively resists the strong Arctic wind
Snow offers excellent insulating properties. Often several igloos are grouped closely together and interior, protected passages connect one structure to another with only one main entrance for that particular grouping of igloos. • The main entrance is protected by a snow wall that is perpendicular to the wind direction and is usually oriented on the windward side of the structure, parallel to the wind direction to avoid snow drifts found on the leeward of the structure. • The entrance on purposely lower than the surface of the snowpack and provides access to a series of transitional spaces, called iglik. As one enters the igloo, through the buried and curved tunnel, the floor rises until the iglik is reached through a low bulkhead. The gradual rising floor elevation allows a pragmatic stratification of the air mass within the igloo that collects the warmer indoor air within the iglik and confines the cooler air to the natiq. • The hanging skins and the final low bulkhead, separating the main space, help further to confine and tratify the air mass and block draughts from the exterior. Outside Air is -50C, the top of dome can be as high as 15C, and close to zero in natiq. • It is constructed of dry snow blocks that piled one on the other in an inward spiral, snow has a low conductivity and help conserve interior temp. (59F or 15C). in summer, they use turf, earth and driftwood to construct sod-roofed dugouts.
A small window if ice that is curved from an available ice pack and sealed within the hemispheric envelope facing the sun. During summer, skins are hung on the interior of the dome to create a relieving dark environment (long daylight). • Fig 17.6, Comparison of temp insides and outside of an igloo (handout page 2).
In Savanna (tropical wet and dry), seasonal rains of varying intensities, homes are dome or cone shaped to facilitate drainage during wet spells, constructed of grass, mud, branches, animal skins (now replaced by cement block types).
Mediterranean climate (dry in summer wet in winter). Dual problem of seasonal climates. Combination of arid regions with those of cool, wet season. Older dwellings in such region, ranging back to Roman times, are identified by a central open courtyard. These are shaded during the day, no direct overhead in these latitudes. At night, they are effective radiators, microclimate further modified by fountains and pools in the courtyards.
Courtyard (figure 13.3b). perform cooling effect. Keep daytime courtyard temp to a minimum by shade and evaporation. Example, tall wide canopy trees offer shade and provide thermal transition zone insolating the courtyard climate from the ambient air above it. However, it will diminish radiation cooling at night. So build a parapet on the buildings perimeter and sloping the roofs inward to the courtyard. The periphery parapet will reduce wind speed over the roof, facilitate radiation heat loss and induce cooling of the boundary-layer air next to the roof surface, and allow cool air drain towards the courtyard. • Water body: a fountain that sprays a fine mist into a pool or sprinkling the large vegetative canopy, or water sheeting down the surface of a large wall. Psychological effect, make one feel cooler. • Wind catcher or tower to harness the commonly strong daytime wind. Openings at the top of the tower are directed parallel to the wind, which is funneled downward into the building and exits across a pool of evaporating water. The effect is an evaporative cooling process that introduces cooler air into the building at the lowest level and allows warm air to rise and exit through a ventilation opening on the roof (stack effect).
Climate and modern structures • Construction of a home or business that uses its background climatic environment as a resource benefits in many ways: economic (decreased energy costs), aesthetic (exhibited by landscape design). • Basic element: solar radiation. Cold region welcomes direct solar radiation inside house and on the walls; hot climate avoid it.
Two seasons, reduce ventilation and increase insolation during winter, let in cooling breeze and shield the insolation during summer.
How to calculate solar angle at give day of the year at a location?
Solar altitude = 90 – (latitude +/- declination of sun (negative sign is used when both in the same hemisphere; positive sign used if they are on diff. hemisphere). • Ex, in winter solstice, when sun is overhead 23.5S, the altitude of the noon sun at 41N is altitude=90-(latitude+23.5)=90-(41+23.5)=25.5 • In summer solstice, overhead at 23.5N; altitude=90-(41-23.5)=72.5
Example of house design in hotand arid climateFig 13.3, Applied Climat.North/south oriented building-maximizing majority of wall surface of the structure facing either east or west, the exposure to south or north is minimal, little wall to charge glaring sun from south. Spacing between adjacent dwellings east-west of one another should created mutual shading of the east-west wall to reduce intense morning and afternoon solar radiation. Space should be 3 times the height of the buildings allowing sun to strike east- and west-facing walls between 11:00and 13:00 hoursSolar protect of the walls at either end of the row of the adjacent dwelling can be “shadowbelt” (for example, trees, for shading and noise and pollution barrier).
Indoor temperature has smaller diurnal variations • The maximum and minimum temperature occur later indoor
