 raditional passive solar homes are oriented with their long (east/west) axis facing south or slightly southeast. In winter the sun's angle is low and sunlight shines directly through the south facing glass, heating up the thermal mass (masonry floors or walls) inside. At night when indoor temperatures cool, this mass radiates its solar heat into the home.
In the summer correctly-sized roof overhangs shade south windows from the sun and thermal mass absorbes unwanted heat keeping the interior temperatures more comfortable.
Notice the shadows in these pictures, taken on June 21 (Summer Solstice) and December 21 (Winter Solstice) and how the roof overhangs work with the sun's angle to control solar gain in a home.
SOLAR HOME DESIGN THEORY
 Conventional wisdom states that south facing windows gain more heat than they lose, north windows lose heat and east and west windows lose as much as they gain. This is why traditional solar homes have a large amount of glass on the south, few (if any) windows on the north. Old style solar homes often used trombe (rhymes with mom) walls which are south-facing, solid masonry walls built 6 inches behind south facing windows. Trombe walls are heat sinks that absorb solar heat then naturally release it at night when the air temperature cools. Their down side is that they are a solid wall inside (or have minimal openings) which limit day lighting and views and they are generally considered ugly. Clerestory windows (high, south facing windows shown in the photos on this page) are another design feature of the older solar homes. They do a decent job with solar gain but are expensive to build and an aesthetic challenge.
THE DOWN SIDE OF TRADITIONAL SOLAR HOME DESIGN
 While traditional solar homes were energy efficient, if designed correctly, they were expensive to build, overheated in spring and fall and were difficult to decorate with all the direct sunlight. Perhaps the biggest obstacle is that many people find the architectural style of a traditional passive solar home unattractive. These negatives have been the downfall of passive solar homes as we knew them but the fundamental ideas of using renewable resources are still sound.
Our challenge became how to design a home that takes advantage of the positive aspects of passive solar design without the negative. Read on to learn about our journey to the solution.
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