CLIMATE RESPONSIVE BUILDING DESIGN IN THE SOUTH AUSTRALIAN CONTEXT
GENERAL'South Australia' is a portion of the land area situated on the central southern coastline of the Australian continent. It is situated between the large continental land mass to the north and the large ocean mass and Antarctic to the south
As a result of solar inflow variation with latitude, in continental terms the large land mass to the north typically is warm, and the water mass to the south is perpetually cool. The interior continental land mass is arid, the summer winds flow over the substantial land area and are also warm. The ocean infiltrates cool air changes across South Australia in the general west to east flow of weather patterns
As a result the general weather patterns in South Australia are typified by cool winters with southwest winds and moisture, and hot summers with northerly winds, either dry and dusty, or tropical.
PASSIVE SOLAR BUILDING DESIGNPassive solar building design suits cool climates where inflow of solar heat gain creates comfortable interior space with limited additional interior space heating
This design approach has some applicability in the limited number of cool climate locations in South Australia
MICRO-CLIMATE BUILDING DESIGNIn arid fringe climate areas the design of buildings for comfort must address:- - resisting summer heat inflow from outside - ejecting the heat build up emanating from occupants and appliances inside the building
This approach is appropriate for comfort design for the majority of South Australia.
Climate responsive building design for South Australia is described in separate
information sheets below about micro-climate, and building cross ventilation using
heat, wind and moisture forces common in the arid fringe climate
THEORY DEVELOPMENTInvestigations about climate responsive building design in the South Australian context are the synthesis of:- - theoretical hypotheses - backed by empirical evidence - applied to building designs both in concept and real life applications.
The hypotheses used have been developed from basic meteorology and physics theory as described above.
Empirical evidence is available from human use of weather forces in other activities. In Australia about 1000 sailplanes achieve 150,000 flying hours in convection weather conditions annually. Convection weather conditions typify the forces available in the climate and are applicable to building design. This is one of the substantial empirical data bases available to the formulation of climate responsive building design principles.
Buildings designed to these climate responsive principles are in operation and are achieving the low energy comfort environments originally postulated.
THE WEATHERWeather occurs everyday. Even though it varies in detail from day to day, it is nevertheless uniformly composed of three contributing influences:- - sun heating - wind - moisture mixed to varying degrees
These forces are the components pieces of micro-climate.
CREATING MICRO-CLIMATEA standard vacant house block can be envisaged as consisting of flat and open ground, unfenced, and with neither structures nor vegetation on it. The climate on such featureless land is the same as that of the surrounding general area weather in which the site is located; that is - macroclimate and micro-climate are the same.
By erecting a building on that land, this changes the climate on the land. This occurs
with every building constructed on every site. Now there is shade cast by the building
onto the ground to the south of that building, and the portion of the site north of the
building receives additional reflected heatload from the building's walls
NATURALLY OCCURRING MICRO-CLIMATEVery seldom is land as featureless as is described above. Existing features on vacant land contribute to modifying the climate on the site from the general area weather. Existing vegetation and structures on the land create shade and moisture variations; land slope and soils change the heating load on areas of the land.
On land with a north facing slope, compared with another with a south facing slope, quite different house designs will be required for comfort. Even where this land is on adjoining allotments. The local micro-climate on these sites is so different that on the south slope high solar inflow is required to achieve comfort, on the north slope solar shading is needed.
USING MICRO-CLIMATE FORCES FOR COMFORTMicro-climate can be used to advantage. Warm external spaces are pleasant places to live in winter, cool outside spaces are comfortable in summer
But these changes to the home site's micro-climate also affect the interior comfort of the building. By creating variations in heatload, wind pressure and moisture on different faces of the home, the interior can be kept comfortably warm in winter and ventilated in summer.
This is described in detail in other information sheets below
THE BENEFITSBuildings designed to use micro-climate are achieving substantially lower energy consumption to achieve the same comfort as conventional buildings; anything between a half and a sixth of normal energy use. That is a lot of money saved on annual operating costs.
ECOLOGICAL DEVELOPMENTMicro-climate is consistent with ecological development principles because the existing features and ecology of the land gives a sound guide to the micro-climate potential and features which should be incorporated in buildings for comfort on each site.
Other information sheets set out some of the detail design options available to enhance the energy savings inherent in good micro-climate building design.
Every day the sun tracks through the northern sky over Australia. Each building casts its shadow on its southern side, and reflects the sun's heat from its northern wall and adjacent ground
South Australia is situated in an arid fringe zone, with a substantial summer heat load where building cooling can be a major energy user
The naturally occuring heat imbalance around buildings described above can be used to improve comfort in buildings in South Australia in summer. Several complementary actions are involved.
As air temperature increases locally, that air parcel expands and reduces in density. Such a low density air parcel has a higher temperature than ambient, and is forced upward by the surrounding ambient air temperature and pressure. This takes the form of thermal convection. This is a common meteorological phenomenon.
On the northern side of a building, this temperature imbalance can be exentuated by constructing hard wall and ground surfaces which reflect solar heat, and these can be formed into a sunken or walled courtyard configuration to maximise the temperature imbalance created.
As air humidity increases, the density of that air parcel increases and the temperature decreases because the latent heat capacity of the air also increases.
Buildings cast shadows to their south. The air in this external area abutting the building is cooler than ambient. This air temperature can be further contained by adding more shade in the form of verandah or pergola, and adding humidity with vegetation, spray or drip irrigation or water features including fountains.
Buildings designed with both these micro-climate features are suited to summer cross ventilation. Opening of windows on north and south sides allows cool and humidified external air from the southern side to infiltrate the building while the building air volume is drawn out to the north by the thermal convection.
The calculated effect of this mechanism in an effective installation is up to 9 air changes per hour. The effect is to create air changes within the building with cooler than ambient air suitable for comfort in summer conditions. The pre-cooled low volume cross ventilation is created with little on-going or recurrent operating costs.
Micro-climate generated cross ventilation is based on simple and well understood meteorological phenomena.
Their application to individual buildings should however be undertaken with care. Poor
building and landscape design in relation to the building's unique site and location can
negate the effects being sought.
Sunken paving with retaining walls or walled courtyard exentuate heating by avoiding wind chill cooling of the space, and minimising air inflow directions, a wall of vegetation can be also be suitable.
For cool spaces, shading by both built enclosure and vegetation are suitable
A clerestorey is high level openable glazing, resulting in the room having a high or sloping ceiling, and associated with it a high, sloping or curved roof on the building.
This high level glazing can be situated over the centre of a room or building to
introduce natural daylight into the house in addition to daylight through windows on
the perimeter walls.
In cold climates, clerestorey can face the sun with a northern aspect, reducing winter heating costs.
The majority of South Australia is situated in an arid fringe climate where summer
cooling is the major energy use
The clerestorey also can contribute to ventilation and cooling of the home in
Ventilation .through clerestorey is generated by the variations in air pressure from
windflow around the home
As air flows around the building, upwind surfaces dam air to higher than atmospheric
pressure. Downwind and sheltered areas contain air at atmospheric or lesser
Effective ventilation depends on replacement air being drawn from elsewhere around
the building. In summer the north winds are hot, dry and dusty, and direct ventilation is
During summer weather changes characterised by south-west `cool change' conditions,
opening the clerestorey to act as an air-in ram bringing cool air into the home to rapidly
cool the structure.