Building orientation can maximize opportunities for passive solar heating when needed, solar heat gain avoidance during cooling time, natural ventilation, and daylighting throughout the year. Southern exposure is the key physical orientation feature for passive solar energy in the northern hemisphere. In winter, the sun comes up in the southeast and sets in the southwest. In the summer, the sun comes up in the northeast and sets in the northwest. In the middle of the day in the summer, the sun is high in the sky overhead. In the middle of the day im the winter, the sun is low in the southern sky. South-facing walls achieve the most solar gain during the winter, while the least in the summer. When trying to use solar energy during the winter for passive solar heating, south-facing glazing(windows) is desired.