Passive solar heating makes use of the sun's heat and energy without requiring special mechanical or electronic elements. Any time sun beams through a window, heating a room, this is a basic example of passive solar heating. This type of alternative energy use can be built into the design of a home or other place where controlled heating is required, such as a swimming pool. If a passive solar heating system can be installed in the initial building of a house, it can reduce energy costs and require little additional expenditure.
Windows are often the key to home-based passive solar heating. Some experts recommend ensuring that the house is oriented so that most of the large windows face south in the northern hemisphere, or north in the southern hemisphere. This ensures an adequate exposure to sunlight throughout most of the year. Windows may receive a special glazing that can enhance the amount of heat generated, or, in warmer climates, can ensure a supply of light without raising heat. Ideally, windows are built to get full sun in winter, and be naturally shaded by other building elements or window blinds during hot summer days.
Once sunlight passes through the windows, it is important that it falls on a substance that can absorb its heat. Certain floor and ceiling materials, such as concrete and stone, are recommended by some green building experts. Painting walls and floors a darker color can also help with passive solar heating, since dark colors can absorb more energy than lighter ones.
One of the keys to passive solar heating is ensuring that it does not make temperatures unbearable during hot months. If a house is designed to constantly maximize heat, the interior of a house can quickly become baking hot during a warm spell. Many people install blinds or removable awnings that can help prevent sunlight from reaching the windows when it is already warm. Proper insulation in walls and windows can also help keep temperatures at a happy medium, rather than soaring too high or low due to external temperatures.
Passive solar heating techniques can be applied to water heating as well as space heating. Passive solar water heaters can be a good way to cut down on energy costs, and are often simple to install and use. For swimming pools and household water, passive heating can be as simple as ensuring that a portion of the piping has full-sun exposure, so that water can be heated naturally on warm days. In swimming pools, some people also use solar rings and blankets, which are dark fabric devices laid on the water's surface to absorb sunlight and distribute it to the water.