passive solar
Passive solar design creates buildings that have comfortable temperatures day and night, year round, without relying on artificial heating or cooling (defined as "active" temperature control systems). Mind you, passive solar requires active occupants - they need to adjust window & door openings, open & close curtains. Passive solar design also reduces electricity demand for lighting (by maximising daylighting) and refrigeration (with cool refrigeration bays and cool pantry design).
It is not necessarily any more expensive in the short term to design for passive solar, nor do passive solar houses need to look terribly different to conventional ones. There are thousands of examples around the world built by countless people, from top architects to illiterate peasants. Here is one example that suits our climate (warm temperate/ cool subtropical NSW mid north coast).
Orientation from 15º East to 20º west of true North.
Planshape a long axis facing North, maximum width 2 rooms and 7.2m.
Glass placement most glass to the north, some to the south for cross ventilation, minimal glass to east and west to avoid overheating in summer and cold winter wind.
Room placement most heavily used daytime areas (kitchen, living) to the north side.
Insulation retards heat flow, keeping summer heat out and winter heat in.
Glass (except double glazed) has almost no insulation value. Windows need good curtains with pelmets, or insulated external shutters.
Cross ventilation draws heat out of a room. It works best when directed in at body level, passes over the skin (which achieves evaporative cooling from sweat) and is exhausted up high. Cross ventilation is great for cool summer breezes but hot summer westerly wind needs to be kept out of a house.
Eaves carefully set to exclude summer sun and admit winter sun. The critical angle is about 52º.
Thermal mass slowly absorbs and releases heat, evening out daily extremes. Unfortunately many thermal modelling programs are unable to calculate the influence of thermal mass on passive solar performance.
Insulated thermal mass gets the best of both worlds. Examples are: timber frame on concrete slab, reverse brick veneer.
Case Study
We prepared this concept for a house at Port Macquarie on a steep, north facing slope, with good views to the north.
A split level arrangement allowed light, heat and cross ventilation into every major room. Strategically placed green roofs reduced summer heat and glare as well as providing extra outdoor space.
