How to Do It!
(see below for a New Way to Measure Outdoor Lighting)
Five Easy Steps
- Use only WHEN you need it
- Use only WHERE you need it
- Direct all the light DOWNWARD
- Use the right AMOUNT of light
- Use the most EFFICIENT lamp
If your neighbor's light is hsining imprperly, ask them nicely and show them a better way to do it. If they say that a new and more efficient light costs more, remind them that 90% of that cost is the electricity to light it and a motion detector would be paid off in short order.
Most of the time, the useful light is the light shining on the ground so that we can
see where we are going.
A simple change. All the light DOWNWARD and the street (and only the street) is much more well lit.
A Cheap Example:
GOOD LIGHT FIXTURES: www.skykeepers.org/odlight.html
New Way to Measure Outdoor Lighting
Historically, all lighting has been measured using only our photopic (daylight) vision. Our photopic vision is that portion of our eye that uses the cones. Researchers have now determined that we use both types of vision (photopic and scotopic) in low light levels (.01 lux to 3 lux). They call this range Mesopic vision.
The measurement that is used in this low light range is Visuallly Effective Lumens (VEL). The scale used is the Scotopic to Photopic Ratio (S/P). A simple example follows:
- HPS 150W – 150W times 56.9 lumens per watt times S/P ratio of .62 = 5292 VEL
- Induction 70W – 70W times 80 lumens per watt times S/P ratio of 1.96 = 10,976 VEL
LED and induction lighting have much higher S/P ratios (and efficiency) than High Pressure Sodium and Metal Halide lamps. Start asking your local Government what the S/P ratio is for any new light.
www.lrc.rpi.edu/programs/solidstate/assist/pdf/AR-VisualEfficacy-Jan2009.pdf
If you want to start working on your local goverment, then you should review the work of other folks first. If you need help, then contact me at mailto:darkskygeorgia@earthlink.net
Examples follow:
www.fairfaxcounty.gov/dpz/zoning/lightingbrochure.pdf
www.shorewood-hills.org/dark_sky/dark_sky.htm
www.town.southampton.ny.us/deptdirectorygallery/land/forms/brochure.pdf
media.skyandtelescope.com/documents/gnol.pdf
www.uwsp.edu/cnr/uwexlakes/humanimpact/lighting.pdf
Wisconsin’s Model Code
darkskywisconsin.uwex.edu/resources/ordinances/WI%20Exterior%20Lighting%20Code.pdf
The main focus of information and links relating to outdoor lighting is the International Dark-Sky Association, at www.darksky.org/mc/page.do
Residential Lighting Help:
docs.darksky.org/PG/PG3-residential-lighting.pdf