Links
A special feature from "Living on Earth"
Pupil Lumens
The concept of pupil lumens was first introduced by Sam Berman of the Lawrence Berkely labs in 1991 following studies of human visual response to light at different wavelengths. His study indicated that the human eye responds to light at the blue end of the spectrum more readily than at other wavelengths. He theorized that it would be possible to maintain visual performance at lower light levels at higher colour temperatures and with good colour rendering, and created a formula for calculating conversion factors. Although this theory and formula have not yet been scientifically proven and are therefore not universally accepted, there are many lighting professionals who believe that there is some validity to the concept of better visual performance in different colour temperature environments.
For further information on this subject please visit
Tuning the Light Spectrum To Improve Energy Efficiency (IAEEL)
Lighting: HID Versus Fluorescent for High-Bay Lighting (esource.com/Business Energy Advisor)
HID Versus Fluorescent for High-Bay Lighting (BC Hydro)