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See also Daylight Saving Time

Daylighting features such as this oculus at the top of the Pantheon in Rome have been in use since antiquity.

The history of lighting is dominated by the use of natural light. The Romans recognized the Right to Light as early as the 6th century and English law echoed these judgments with the Prescription Act of 1832.^[25][26] In the 20th century artificial lighting became the main source of interior illumination.

Daylighting systems collect and distribute sunlight to provide interior illumination. These systems directly offset energy use by replacing artificial lighting and indirectly offset non-solar energy use by reducing the need for air-conditioning.^[27] Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting.^[27] Daylighting design carefully selects window type, size, and orientation and may also consider exterior shading devices. Individual features include sawtooth roofs, clerestory windows, light shelves, skylights and light tubes.^[28] These features may be incorporated into existing structures but are most effective when integrated in a solar design package that accounts for factors such as glare, heat flux and time-of-use. When daylighting features are properly implemented they can reduce commercial lighting related energy requirements by 25%.^[29]

Hybrid solar lighting (HSL) is an active solar method of using sunlight to provide illumination. HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit the light into a building's interior to supplement conventional lighting. In single-story applications, these systems are able to transmit 50% of the direct sunlight received.^[30]

Although daylight saving time is promoted as a way to use sunlight to save energy, recent research is limited and reports contradictory results: several studies report savings, but just as many suggest no effect or even a net loss, particularly when gasoline consumption is taken into account. Electricity use is greatly affected by geography, climate, and economics, making it hard to generalize from single studies.^[31]

See also Daylight Saving Time

Notes