Solar Lighting
The Solar Energy Research Facility (SERF) at NREL uses a light shelf on the south side for daylighting. It also has a small square windows on the east and west to minimize glare.
Throughout the 1900s, use of the sun as a source of energy has evolved considerably. Early in the century, the sun was the primary source of interior light for buildings during the day. Eventually, however, the cost, convenience, and performance of electric lamps improved and the sun was displaced as our primary method of lighting building interiors.
Attempts to use sunlight directly for interior lighting via lens collectors, reflective light-pipes, and fiber-optic bundles were the next step.
The most recent technology, Hybrid solar lighting, collects sunlight and routs it through optical fibers into buildings where it is combined with electric light in "hybrid" light fixtures. Sensors keep the room at a steady lighting level by adjusting the electric lights based on the sunlight available. This new generation of solar lighting combines both electric and solar power. Hybrid solar lighting pipes sunlight directly to the light fixture and no energy conversions are necessary, therefore the process is much more efficient. It is currently being developed and tested by Oak Ridge National Laboratory in collaboration with the Department of Energy and several industry partners.