A passive solar building is designed and built based on utilizing the constants within the surrounding environment, centered around the movement of the sun.
Passive solar buildings will be warm in the cold winters and cool in the summer if planned and built according to a few passive solar building rules. Passive solar design works with the sun’s heat energy to both to warm the building and is designed and situated to block the sun in the warmer summer months to keep the building cool.
The sun rises in the east and sets in the west. If a structure has windows on the southern facing side of the building, it can potentially receive the sun’s warmth (heat energy) all day.
In order for passive solar design to function, most of the building’s windows must be located on the southern facing side of the building.
In the summer, the sun travels higher path in the sky than it does in the winter. Thus, if the proper roof or window overhang is constructed, the house can receive the full winter sun, while the house is shaded by the overhang during the summer.
See pictures of the sun’s rotation on the winter and summer solstices.
When a passive solar building is designed and build well, the building simply, passively sits there and will be warm in the winter when it is cold outside, and will be cool in the summer when it is hot outside.
Passive solar design generally works with the following principles:
1. The sun travels different routes in different seasons. The winter sun travels a lower route in the sky than the summer sun.
2. If glass windows are located facing the south, in the winter, they allow the sun’s energy to be absorbed and stored within the building.
3. If the thermal mass is located (usually in the floor and walls) where it can absorb the sun’s energy, it will absorb, then slowly release or distribute the stored heat energy through the evening and night.
4. If the proper control, or overhang is constructed over the windows, the summer sun can be blocked from entering the building. The lack of direct sun allows the structure to stay a cooler temperature.
5. If the building is properly insulated, it will retain its warmth in the winter, as well as its coolness in the summer.
Passive solar design utilizes energy from the sun, using its predictable movements through the seasons to heat and cool a building without any additional mechanical devices (hence the name – passive solar). It can be thought of as the aikido of architecture.