Harnessing sunlight for free heating in winter, and conversly keeping it out in summer to remain cool, is the heart of Passive Solar Design.  The secret to high thermal performance is to work a floorplan, along with window placement, so that you can get winter sunlight into as many rooms as possible.  Not only does this give free heating, but it also connects the occupant with the outside, and keeps light levels up, removing the need for electrical lighting in daylight hours, and generally making spaces naturally nicer to be in.

All over the world,the sun rises in the East and sets in the West.  For Melbournians, as we are lower in the southern hemisphere, it does not go directly overhead, but travels across the northern half of the sky.  We can take advantage of this by arranging our floor plans locating important living spaces on this northern side of the house, so that with some judiciously placed windows, we can get winter sunlight shining in for most of the daylight hours, to warm the space.  Good insulation and thermal mass can then store this heat, to keep room temperatures stable and high well after the sun has gone down for the day.  In summer, correctly designed northern eaves will keep the sun out, to maximise cool.

While living spaces are the most important to get right, the more rooms that can access northern light, the higher your rating will be.  In Melbourne, the second best direction for windows is east.  Since we are trying to heat our homes for most of the year, and since the sun rises in the east, windows in this direction will get the house warming early.  The West is favourable in winter too, but becomes undesirable in hot summer afternoons.  Hence, it is vital also to have a shading strategy for summer...

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