Solar lighting is any type of lighting that uses the radiation from the sun to illuminate a particular area. Since early history, humans have used solar lighting as their main method of illumination. Old laws such as England's Prescription Act of 1832, established minimum rights to illumination through natural methods. In modern times, there are a variety of forms this type of lighting can take such as direct sunlight or even highly-controlled infrastructure installations.
The most common type of solar lighting is called daylighting. This uses passive technologies to light rooms or specific areas. Daylighting takes on a variety of forms, the most common being skylights that are placed in the middle of rooms. An ancient form of this is clerestory windows, which are commonly found in Romanesque and Gothic architecture. They are openings placed at the top of large structures that allow the sun to shine inside. This was very important as the economics of lighting churches and cathedrals with candles was unsustainable. A more modern installation is called the light tube. Light tubes use a series of mirrors which direct the path of sunlight into a room through a tube in a roof.
A recent innovation in this type of lighting is a technologically-hybridized system that uses mirrors which track the sun's movement and follow it as it changes position in the sky. Most of these installations use an optical fiber to transmit the light to the interior of the building. This method is used as a way to supplement or replace existing artificial lighting. The most efficient use of this hybrid system is in single-story buildings.
There are a variety of reasons to use an illumination system that utilizes solar lighting. Many studies have confirmed the health benefits of regular exposure to sunlight, whereas many forms of artificial light can actually cause health problems in some. The human body converts solar radiation that hits the skin into vitamin D, an essential element. Solar lighting also allows the body to get a higher dosage of indirect rather than direct sunlight, giving one the benefits of sun exposure while minimizing the chances of skin cancer.
The majority of solar lighting transmits 50 percent of the direct sunlight it receives. This can offset the need for much of the artificial lighting used by modern society, both in the home and many work environments. A transition from artificial lighting to solar lighting would have obvious repercussions regarding energy consumption and money savings. The U.S. Department of Energy estimates that the average skylight placed in a home pays for itself within five years through lower electric bills. Solar lighting can also cut down on heating costs. During the winter, it keeps the area warmer by harnessing the sunlight.
