Millions of buildings are constructed every year with large windows facing every direction, but up to 60% lighting, heating, & cooling energy could be saved by this simple, costless measure.
In winter, the sun appears low in the southern sky, welcome warmth enters the building through south-facing windows. The opposite is true of west- and east-facing windows, which allow only a few hours of sunlight in winter, losing more heat than they gain. In summer, unwanted heat comes in west and east facing windows. (Nothing to sell on this informational website.)
Tilt of earth relative to sun changes with season
NO,THE WINDOWS DON'T HAVE TO BE HUGE! Oversized windows are not necessary and may be undesirable. Excessively large, uncovered windows lose great amounts of heat at night and may allow excess heat to enter in the summer.
Early passive solar buildings featured huge expanses of glass, which overheated the buildings in the daytime, and lost uncomfortable amounts of heat after dark. For achieving an ideal balance, calculations will estimate building heat loss vs. solar gain, per National Renewable Energy Laboratories (NREL).
WINDOWS SOUTH, AND INSULATE !!!!!
It is a falacy that less insulation is needed in a solar house. During winter the sun is not shining during the majority of the hours. Also, insulation keeps unwanted heat out in the summer.
36% of the nation's energy is used for building energy needs.
If architects, engineers, and builders were to apply this one simple, costless principle, not only would huge amounts of energy be saved at peak-load hours, but building occupants would be much more comfortable.
For detailed information, the book More Other Homes and Garbage by Stanford professors Gil Masters, et al., is available through your library or bookstore.