The sale of lighting is very competitive. They offer more light to solve your perceived problem. But, what if your problem is too much light? It is unlikely they will recommend less light.
Almost all luminaires are designed for an urban environment to produce as much light as possible. But do you really want your park or residential street to look like a major roadway?
Other lights may look nice in a sales brochure or in pictures taken at twilight, but the same fixtures may produce glare and light trespass at night when you really want to "see".
|People need to experience the night and experience nature, so provide access to those spaces but don't light them like a prison yard. Some of the most memorable areas are in places where people want the least amount of light: parks, pathways and wilderness areas. In these areas a little bit of light can do much without undermining the experience.|
2) You can read a map by using an illumination of 1-lux (0.1-fc). That's 1 lumen/m2, or about 10 mW/m2 of electricity. How many watts are you using?
3) Your reaction time is about 1/4-second at 3-lux. A city street may be lit to 5-50-lux! However the reaction time of a motorist is over 1-second, due to distractions. Therefore, it's better to reduce the distractions than to increase the illumination levels.
4) At 1-3-lux, with no blue-light spectral components, you can retain some of your night vision - allowing you to see well past the illuminated area.
5) The "bright spot" at nadir under the lamp reduces your vision beyond the illuminated area. Uniformity (max/min, not the max/average) is important.
6) Visibility of the exposed light sources (light bulb or LED emitters) dominate the field of view and makes the uniformity of ground illumination almost irrelavant.
7) The efficacy of typical LEDs (2014) and "modern" HPS lamps are both about 110 lm/w. LEDs ONLY make electrical sense when they replace decade-old HPS, MH and incandescent fixtures - of which there are many beacuse they have lasted so long and have proven to be been quite reliable. So, why change to LEDs? . . . .
8) LED luminaires have great potential. They can be more easily controlled by "Smart Systems". They can be dimmed and turned off when not needed. This is where we will find the the energy savings.