Passive Solar Design is actually an ancient idea. It is about harnessing climatic effects and natural energy flows, to produce a building that provides comfortable internal temperatures.
Using the fact that the sun travels higher in the sky in summer and lower in winter, we can design floorplans, and strategically place windows with appropriate eaves, that let winter sun deep into the house to warm, while keeping out summer sun.
By looking at where local summer winds blow, we can design breeze paths through the house that encourage the wind in for natural cooling and fresh air.
By locking to the mass of the earth, and introducing heavyweight building elements inside the house, we can make sure that temperatures remain very stable internally, regardless of external fluctuations.
We further refine these basic ancient ideas with modern innovations; excellent insulation, high performance glazing, and computer simulation.
The outcome, are homes that need very little extra heating or cooling, as by design, they are working with nature to provide comfortable temperatures. As a by-product, you also get homes that are full of natural light, and connect wonderfully to the outside.