Jeff Werbock
07-14-2001, 04:34 PM
So far, two criteria for energy efficiency in lighting products have been established. One is the lumen output of the lamp pre watts consumed, the other is the optical efficiency of the luminaire for getting light out of itself. This paper proposes a third criterion, which is where the light is directed.
If the light is directed at surfaces that do not efficiently return light to the viewing eye, it is
tantamount to turning on a faucet and walking away. Examples are black macadam, most floors, carpeted or otherwise, and the open sky.
If light is inadvertantly directed at the viewing eye, it reduces visibility of the surfaces of interest.
If the available watts for illumination are concentrated on select areas, the ensuing glare will reduce the visibility of the other surfaces in the same space.
If the available watts for illumination are directed at floors or ceilings, there will be a reduced benefit of general visibility, because people do not look down at floors or up at ceilings, they look around and mostly see walls, and other vertical surfaces.
Solutions:
Stop using downlights indiscriminately. Use them only where there is a real need to illuminate a horizontal surface, such as a work station, a conference table, a dining room table, etc.
Stop bouncing light off of ceilings. It makes the ceiling significantly brighter than the other surfaces you need to see, reducing the visibility of those surfaces.
Stop aiming accent lights at vertical surfaces. They produce concentrated select areas of brightness, which reduces visibility of every other surface in the same room. Use equipment with spread lenses which distribute the available watts evenly across the vertical surfaces, providing excellent contrast ratios which is essential for good visibility.
Put a reflector cowl around every cobra head, redirecting the blast of glare to the road surface, and keeping it out of the tired eyes of nighttime drivers. Install motion sensors in street lighting systems to turn them off when no one is around. Use a material that is more reflective than macadam for road surfaces.
Stop using multi-tap transformers to drive low voltage systems. Multi-taps enable contractors to use thinner, cheaper wires to power low voltage lighting systems and not result in voltage drop, which impairs lamp performance. This practice is an egregious waste of electrical energy, and its practice is becoming widespread, unacceptable in the coming energy crisis. Instead, use regular transformers and force the contractors to install the proper gauge wires to handle the loads.
The unintelligent use of electricity for lighting is making a major contribution to the developing energy crisis. Either we start now upon a program of intelligent use, or face regulation, which will almost certainly not understand and take into account the realities of lighting.
If the light is directed at surfaces that do not efficiently return light to the viewing eye, it is
tantamount to turning on a faucet and walking away. Examples are black macadam, most floors, carpeted or otherwise, and the open sky.
If light is inadvertantly directed at the viewing eye, it reduces visibility of the surfaces of interest.
If the available watts for illumination are concentrated on select areas, the ensuing glare will reduce the visibility of the other surfaces in the same space.
If the available watts for illumination are directed at floors or ceilings, there will be a reduced benefit of general visibility, because people do not look down at floors or up at ceilings, they look around and mostly see walls, and other vertical surfaces.
Solutions:
Stop using downlights indiscriminately. Use them only where there is a real need to illuminate a horizontal surface, such as a work station, a conference table, a dining room table, etc.
Stop bouncing light off of ceilings. It makes the ceiling significantly brighter than the other surfaces you need to see, reducing the visibility of those surfaces.
Stop aiming accent lights at vertical surfaces. They produce concentrated select areas of brightness, which reduces visibility of every other surface in the same room. Use equipment with spread lenses which distribute the available watts evenly across the vertical surfaces, providing excellent contrast ratios which is essential for good visibility.
Put a reflector cowl around every cobra head, redirecting the blast of glare to the road surface, and keeping it out of the tired eyes of nighttime drivers. Install motion sensors in street lighting systems to turn them off when no one is around. Use a material that is more reflective than macadam for road surfaces.
Stop using multi-tap transformers to drive low voltage systems. Multi-taps enable contractors to use thinner, cheaper wires to power low voltage lighting systems and not result in voltage drop, which impairs lamp performance. This practice is an egregious waste of electrical energy, and its practice is becoming widespread, unacceptable in the coming energy crisis. Instead, use regular transformers and force the contractors to install the proper gauge wires to handle the loads.
The unintelligent use of electricity for lighting is making a major contribution to the developing energy crisis. Either we start now upon a program of intelligent use, or face regulation, which will almost certainly not understand and take into account the realities of lighting.