Natural lighting refers to the admittance of light from the sky into internal spaces and is a key factor in the design of energy efficient commercial buildings. Properly used, it can result in substantial energy savings by reducing the need for artificial lighting. The primary aim of natural lighting is to provide sufficient light under all circumstances for the tasks performed within a space. If such a lighting level cannot be achieved by natural light alone, then localised artificial task lighting can be used to supplement.

Figure 1 - Natural light plays an important role in our appreciation of internal spaces.

On a clear summer day, outside light levels can be as high as 100,000-120,000 lux on a horizontal surface, whilst on a dark overcast winter day this might fall to around 4,000-5,000 lux (depending on the latitude of the location). The required light levels inside a building range from 100 lux in an access corridor, 300 lux on the desktop in an average office, 800 lux on a drawing board, and up to 1200 lux for display cases in a supermarket. With some thoughtful and innovative design, natural lighting can potentially provide more than enough light for most applications in almost any type of building.

Figure 2 - Examples of the use of light-pipes and natural light diffusers.

Related Links

K. P. McGuire, 'Daylight - Is it in the eye of the beholder?'

http://www.solux.net/edu13.htm

Advanced Lighting Guidelines - 2003 Edition

http://www.newbuildings.org/lighting.htm

Energy Efficient Technologies - Daylighting Design

http://www.energydesignresources.com/category/daylighting/

EcoAdvisor - Daylighting

http://www.ecoadvisor.com/html/ecoDaylighting.htm

Daylight and Natural Air Flow

http://greenbuildings.santa-monica.org/envelope/envairflow.html