Heating and cooling buildings contributes to more energy usage than any other aspect of a buildings use. A building which is well insulated will reduce the energy costs of heating and cooling. There are many methods to keep a buildings environment comfortable while minimizing energy input including:
- Roof ponds
- Thermal mass walls
- Solar chimneys
- Solar rooms
- Green roofs.
Passive Heating & Cooling
All methods of passive heating and cooling rely directly on the sun for energy input. Due to this reliance on the sun one of the most important aspects of a building is its solar orientation. A building that is shaped like a rectangle (with side lengths having the ratio of 1.6 to 1, the golden ratio, being ideal) and elongated in the east-west direction is the optimum shape in all climates.
Roof Ponds
Roof ponds are a particularly effective method of keeping a buildings temperature constant. To create a roof pond, water is stored in bags inside the actual roof structure. Because of water’s high specific heat capacity, water can store hot or cold temperatures better than most materials. During the summer, the bags of water are covered during the day and uncovered during the night. During the night, the water is cooled down by nighttime temperatures and during the day the cool water keeps the house cool. During the winter the exact opposite approach is taken. The daytime heat is soaked up with the water bags uncovered and during the night this heat is released into the building when the bags are covered up. This set up has the potential to keep temperatures nearly constant in even extreme temperatures.
Green House Effect
Another option builders have is to take advantage of the greenhouse effect: glass allows solar energy waves (visible light) to pass through it but does not allow heat (infrared) to escape. To take advantage of this fact, builders can create a glass enclosed room containing a material (usually the floor or a trombe wall) with low reflective and high specific heat. When light hits this material, the energy becomes heat and is not allowed to escape from the room. Also, because the material has a high specific heat, it is able to store energy and release it over a longer period. Just like the roof ponds, one can selectively cover the windows during different times of day and temperatures to control the space’s temperature. Large cement blocks, rocks, and different types of containers filled with water can act as excellent materials for this application.
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