Good, clear presentation of Seasonal Window Considerations for Passive Solar homes. Windows must be climate sensitive: check to see if they show be double or triple paned, or even covered with a thermal shade in coldest climates.
The sun 'travels' different paths throughout the season. The summer sun is high, while the winter sun is low. Passive solar design situates the house and is built with certain materials to help it to be warm in the winter and cool in the summer.