* In summer, excess heat comes in west and east facing windows.   
The heat generated by one 6 ft by 6 ft window facing east or west is equivalent to burning one gallon of oil in the building each summer day! ! ! !   From April through September the sun rises in the northeast and sets in the northwest, glaring high overhead midday.

* In winter, when the sun appears low in the southern sky, welcome warmth enters the building through south facing windows. 
West and east facing windows get only a few hours winter sunlight while losing far more heat than they gain.


Ancestral use of natural shading.

Shading Overhang over South Window

A properly sized overhang shades south-facing windows from the high summer sun,  yet allows the warmth from the low winter sun to enter during the cold months.