Figure 4.10 Elements of the passive heating system

 Control: The control is achieved through the use of shading devices, or some other means to regulate the sunlight entering the building. Devices such as roof overhangs used to shade the aperture area and prevent overexposure to the solar radiation during summer months and prevent overheating.

The size and shape of the solar apertures (collection subsystem) affects the quantity of heating energy available to offset auxiliary heating energy needs. The size of the storage subsystem affects the quantity of heat stored and the time delay between initial collection and final use of energy. The size, shape, and location of rooms in the building impact the optimum distribution of the heat throughout the building.

Heat distribution is accomplished by a combination of radiation and convection. Heat is radiated from the storage subsystem into the rooms being heated after the collected solar energy has passed through the storage system. Heat is convected through the air, warming it, and thereby warming the people in the room.

Figure 4.10Elements of the passive heating system

Types of passive heating systems

When a storage surface is illuminated by sunlight, the energy enters the mass and is stored as heat. The type of material used, its thermal storage capacity, thermal conductance, thickness, and the room’s temperature dictate the quantity of energy stored and the length of time it stays in storage.

For example, a 4-inch concrete wall might store energy for 4 hours before completely releasing it as heat. Similarly, 24 inches of concrete might store energy for 18 to 20 hours before completely releasing it.

By varying the type of building material used, and its thickness, it is possible to substantially vary the performance characteristics of a passive heating system. The most commonly used materials in storage systems are concrete and masonry products.

In regard to how fast the storage system store and release the heat, they can be prompt or extended: