PrintPassive systems do not use mechanical devices such as fans, blowers, or pumps to distribute solar heat from a collector. Instead, they take advantage of natural heat flow to distribute warmth. An example of a passive system for space heating is a sunspace or solar greenhouse.
Passive systems also make use of materials with large heat capacities (stone, water, or concrete) to store and deliver heat. These are called thermal masses.
Instructions: Click on the hot spots in the image below to see the essential elements of a passive solar system.
Passive systems can be categorized into three types:
- Direct Gain - Allows the solar energy to come in through the south-facing window panes.
- Indirect Gain - Allows the solar radiation to heat a wall and then the energy is slowly delivered into the interior of the house. Openings in the wall (called a Trombe Wall), as shown in the figure below, promote convective currents:
- Cold room air enters the space between the glass panel and the wall through the bottom opening.
- As this cold air gets heated, it rises to the top and comes in through the top opening.
- Greenhouse Addition - An attached sunspace and/or solar greenhouse heated by the solar energy - where some of the energy is used to grow the plants and some of it is used to heat the interior of the house.
These systems are shown below.
Illustration of Direct Gain, Indirect Gain, and Solar Greenhouse Addition Methods