|Design Handbook on Passive Solar Heating and Natural Cooling (HABITAT, 1990, 162 p.)|
|V. Basic design principles and strategies|
1. Hot-arid climates
In such climates where the daily (diurnal) temperature range often exceeds 20 degC the most important principles are to have a large thermal mass (masonry or concrete walls and concrete floors), a well insulated external skin and effective summer shading of windows and walls where possible. As winter daytime temperatures are relatively low. good solar access to the northerly-facing windows is most important. East and west windows should be avoided unless full shading and thermal insulation can be provided. The insulation is necessary for both the heat of the summer day and the cold of the winter night. The design should include breezeway-style living areas for summer evenings. Evaporative cooling is very effective and appropriate in this climate.
2. Cool-temperate and temperate climates
The majority of the country's population lives in either the temperate or the cool-temperate zones. In design terms the winter requirements vary little because of the relatively sunny winters experienced in Australia compared with many other countries. The major differences are related to insulation levels and the like.
In summer there is a greater need for thermal mass in the warmer temperate areas to suppress daytime temperature peaks. In the cool-temperate areas such as Tasmania and the New South Wales tablelands the outdoor temperature in winter rarely rises above the comfort range and so thermal mass is less important for summer as natural ventilation and good shading are quite adequate. In winter the thermal mass is important where solar energy is desired for heating. Where intermittent heating is used in non-sunlit rooms, thermal storage materials will tend to increase the energy needed for heating.
Where east and west windows are required for views etc., effective shading must be provided for summer. With the exception of very hot periods there should be no special requirements for ventilation other than those of fresh air and air movement to avoid stuffiness.
3. Hot-humid climates
The problem of high humidity levels is not easily solved with building design. Although temperatures may not be as high as in the arid zone climates the combination of high humidity and moderately high air temperatures causes discomfort. This is especially so at night when lower temperatures are needed for a sound sleep. The aim is, first, to ensure that indoor temperatures do not exceed outdoor-temperatures. This is achieved by extensive shading (especially on the eastern and western sides of the building), insulation of roofs (reflective foil is appropriate) and most of all, unimpeded natural ventilation. Shading of east and west faes by heavy planting can be most effective in providing both the sun protection and a cool place to sit during the day. The use of ceiling fans to induce air movement is strongly recommended. Elevating the building above the ground has been found effective in low-density areas, but it makes shading from planting more difficult. The design of openings to facilitate airflow is important. The building structure should be of lightweight construction to aid cooling whenever the temperature drops. A concrete slab on the ground is effective in providing a limited heat sink but this must be weighed against the greater need for relief by air movement.