Set D, Good Lighting Slide Set:
Title Slide for the set of eight slides from General Electric.
The specific area that needs to be lit. It is a walkway between two buildings and the building entrance areas.
One could use globes, or other fixtures with little or no control of the light output.
The result: Marginal lighting for the task, and a great deal of waste. More than half the light output is wasted!
One could use a fixture with some control of the light output. Certainly much better than the first choice.
Better, but still a good deal of waste, and the glare level is probably too high for comfort.
Glare never helps visibility.
A full cutoff lighting fixture, one with no direct uplight at all, and with essentially no glare.
All the light is used, none is wasted. No adverse effects of bad lighting.
The result. Clearly, this is the optimal design! Note the added light near the entrances. The risk there is greater than on the path, and so a lower lighting level is appropriate for the path way. One can optimize the energy savings without compromising the result at all. A great lighting design job!
An aerial view of the Pima County Prison installation shown in Slide Set B. Full cutoff fixtures have been used for all the lighting, including fence lighting and wall packs. No direct up light, no light trespass for neighbors, no glare. A great design job.
A new, antique looking, full cutoff lighting fixture on Nantucket Island. The people here are trying to preserve the ambience of the past, and they want to do it with good lighting: safe, effective, and nice looking. This fixture has the light source completely up in the fixture, so that there is no glare and no direct up light. However, because of the design of the fixture, there is excellent control of the light output, giving a good distribution on the ground. In addition, since there is no glare, lower than normal lighting levels are possible (as in the old days, maybe), yet visibility is excellent because the eye does not have to overcome the adverse effects of glare.
A closer view of the same fixture. Note the street name!
Another new, antique looking fixture. Many towns or neighborhood groups want such antique looking fixtures, because they look nice," mostly in the day time. The problem comes when one uses them as a light source. Most have little or no control of the light output, so lighting levels on the ground are marginal. To get more light," one puts a higher wattage lamp in the fixture. Hence, more glare and more waste. Visibility is probably not improved at all, due to the glare. Safety is probably even compromised. The key is to use good design. That means, either 1 ) a good fixture, like this one or the one in the Nantucket design, one that is a full cutoff fixture with good control of the light output, and with lamp wattage to give adequate lighting in the absence of glare, or 2) use very low wattage lamps in the "poor" fixture (see the globe examples and discussion in IDA Slide Set B) and put in a full cutoff lighting system to light the street or the parking lot. This approach has been done in a number of communities, and it works well. The street lighting system is located well above the older system, perhaps 30 feet high, and no one sees it," for it has no glare. Many think that all the lighting is coming from the old system, whereas in fact very little is! Again, creative, quality lighting design does work, and we all win.
A full cutoff lighting fixture in the fog, showing the excellent control of light output. Since there is no glare, visibility is good in the fog, and the lighting system helps rather than hurts visibility.
Another good example.
Another. Imagine lighting fixtures here having poor light control: the glare would be so bad that visibility would be terrible. It would undoubtedly be improved by turning off the lights.
An example of a full cutoff low pressure sodium fixture. Excellent light control is possible with these type fixtures.
Another full cutoff LPS fixture, this time mounted on a wall, for walkway lighting.
Excellent full cutoff wall packs, installed to light the stairways. The parking lot lighting here is also full cut off.
A new car dealership in Tucson, using mostly full cutoff lighting fixtures. They are metal halide lamps, the most effective white light source, and the fixtures are full cutoff, giving excellent control of the lighting. Furthermore, they are time clocked and go off soon after the dealership closes for the night. The dealer reports tremendous energy (and dollar!) savings after converting to this system from his earlier one that used quartz lighting in rather poor fixtures with little control of light output. Furthermore, the neighbors and the passing motorists much appreciate the improvement in lighting quality. The security lighting system is not full cutoff, but remains the older system (some control of light output, but not enough). All newer installations in Tucson are now using full cutoff for all exterior lighting, and two even use low pressure sodium in combination with other (white) light sources, saving even more energy and money without in any way compromising the task of selling cars and providing a safe and secure environment.
A prime example of quality sports lighting, using excellent lighting fixtures with good control of light output. Minimal glare for the players, spectators, or neighbors, and no complaints from neighbors relative to light trespass. Minimal adverse impact on urban sky glow. It can be done, and it should be. When it is, we all win.