Passively heated buildings can be considered a special case of the flat plate collector. The building itself functions as a large solar collector. Passive Systems Passive systems are used to heat homes. They work the same way that the sun heats a room through a window. A passively solar heated house is oriented and designed to absorb and store heat from the sun during the winter, and to keep sunlight out during the summer.
Passive systems have few or no moving parts.
The collected solar heat is stored in the building materials themselves. The roof overhang is specifically designed to admit sunlight in the winter and shade the glass when the sun is higher in the sky in the summer. Strategically placed deciduous trees shade the house in summer and, after they lose their leaves, allow radiation through in the winter. In-ground or underground passive solar buildings and houses take advantage of the steady temperature found just a few feet below ground. This aids cooling in the summer and heating in the winter.