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[DSLF] Digest Number 1464

There are 2 messages in this issue.

Topics in this digest:

      1. remedial measures
           From: "Mark Kinsler" <kinsler33@hotmail...>
      2. Re: remedial measures
           From: ctstarwchr@aol...


Message: 1         
   Date: Sat, 02 Oct 2004 13:08:56 -0400
   From: "Mark Kinsler" <kinsler33@hotmail...>
Subject: remedial measures

I am new to this group.  My question has probably been addressed a thousand 
times here, but there seems to be nothing on it at the International Dark 
Sky Association's website.

I am trying to find out means of reducing skyward radiation from existing 
outdoor light fixtures, primarily street lighting luminaires and parking lot 
lighting.  The IDA website has a description of a cap that can be applied to 
the backyard lights of cooperative neighbors, but it doesn't look like the 
sort of thing that would work on streetlights or the lights at a Walmart 
parking lot.

My guess is that there is existing research on the subject and perhaps 
commercially-available devices to accomplish the task.

M Kinsler
512 E Mulberry St. Lancaster, Ohio USA 43130 740-687-6368

Check out Election 2004 for up-to-date election news, plus voter tools and 
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Message: 2         
   Date: Sun, 3 Oct 2004 07:32:16 EDT
   From: ctstarwchr@aol...
Subject: Re: remedial measures

In a message dated 10/3/2004 6:17:50 AM Eastern Daylight Time,  
kinsler33@hotmail... writes:
> I am trying to find out means of reducing skyward radiation  from
> existing outdoor light fixtures, primarily street lighting  luminaires
> and parking lot lighting.

Hi Mark:
Welcome to the DarkSky List Forum!  In Connecticut we passed a 
state law in 2001 (Public Act 01-134) requiring the use of full 
cutoff lighting on all roadways throughout the state.  
In simple terms, full cutoff lighting permits no light to emit above  
the horizontal plane and it reduces intensity to 10% (for each angle) 
at and above 80° (above nadir) measured in the vertical plane.  See  
the images in the Photos > Photometry folder of the DSLF to see what
this means.
Today we now have thousands of excellent examples in place on CT
roads and this law is working very well to help improve  nighttime 
driver safety while reducing visible skyglow and it also allows 
dramatic wattage reductions for some of the existing applications 
receiving new fully shielded fixture retrofits.
In some cases we retrofitted 400 watt high pressure sodium semi-cutoff 
sag lens fixtures with 150 watt full cutoffs with no loss in visual 
perception and roads still exceed the minimum recommendations of the 
American National Standard for Roadway Lighting ANSI/IESNA RP-8-00.  
Light trespassing into bedroom windows and yards has been dramatically 
reduced and people are speaking highly in favor after they experience 
these results on their properties.  Some have never had dark  bedrooms
before the new lighting was installed.
Fully shielded fixtures with flat lenses installed level will help to 
reduce a lot of skyglow, but some of that light will still reflect upward 
from the illuminated surfaces, so it is vital to also reduce brightness 
to minimum levels recommended in lighting standards to assure adequate 
safety will be provided.  In many cases extreme overlighting has exceeded 
minimum levels and each one allows an outstanding opportunity to save tons 
of money and energy reducing wattage when applying fully shielded  lighting.
In many cases the cost to replace lighting fixtures can be returned  through
savings in a few years.
I have designed retrofit lighting systems that reduced wattage by so 
much the new system paid for itself within 5 years simply by the savings 
achieved on the annual electricity bill.  Visual quality and  aesthetics 
were improved as well.  For some excellent examples of good lighting 
products visit the Manufacturers section of my LiteLynx List at the Light 
Pollution Awareness Website at:
Also see "Good Fixtures and Where to Get Them" on the IDA web site.  
An excellent IDA information sheet titled, "The Environmental Aspects 
of Roadway Lighting" is available that provides good information on 
applying fully shielded lighting.
The Tech Talk section of the LiteLynx List offers outstanding information 
on good lighting practice.

The Citizens for Responsible Lighting web site offers good information 
in the Engineering section.  http://www.crlaction.org 
Also be sure to visit the Links, Files, and Photos sections of the Dark 
Sky List Forum for some excellent educational information.  The following 
axioms are overly simplistic but they apply for reducing light pollution 
1. Apply fully shielded lighting aimed properly to keep direct light below
   the horizontal plane to reduce visible glare as much as  possible.
2. Mount, aim, and shield fixtures carefully to assure direct light stays 
   within the property boundaries  and illuminate only the task areas.
3. Never apply more light than minimally needed for the tasks.
4. Use sensor driven lighting whenever possible and turn the lights
    off when nobody is present to benefit from them.
Other references at the LiteLynx List will lead you to an intriguing
adventure exploring the wild and woolly world of low impact outdoor 
lighting.  Also try some experimenting with your lighting at  home.  
For some ideas check out the shielding section of the LiPAW at:
The best example of industrial applications where incredible savings
were achieved is the Premcor Refinery Group in Port Arthur, Texas.
They reduced wattage in half after applying full shielding on outdoor 
fixtures and save nearly $500,000 on the annual electricity bill while
exceeding minimum OSHA lighting standards for petrochemical plants.  

The most outstanding savings achievement full cutoff  lighting has 
achieved in municipal lighting savings is the City of Calgary, Alberta 
in Canada.  They are saving $2,000,000 annually on  roadway lighting 
costs and have also reduced wattage in half while still meeting the
minimum standards in ANSI/IESNA RP-8-00.
Hope this helps provide a robust foundation on the basic  concepts.
Clear skies and good seeing,
Keep looking up!

Cliff  Haas
Author Light Pollution Awareness Website  (LiPAW)


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