Day lighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to day lighting while designing a building when the aim is to maximize visual comfort or to reduce energy use. Energy savings can be achieved either from the reduced use of artificial (electric) lighting or from passive solar heating or cooling. Artificial lighting energy use can be reduced by simply installing fewer electric lights because daylight is present, or by dimming/switching electric lights automatically in response to the presence of daylight, a process known as daylight harvesting.
Day lighting is a technical term given to a common centuries-old, geography and culture independent design basic when “rediscovered” by 20th century architects. The amount of daylight received in an internal space can be analyzed by undertaking a Daylight factor calculation. Today, the use of computers and proprietary industry software such as Radiance can allow an Architect or Engineer to quickly undertake complex calculations to review the benefit of a particular design.