Every once in a while, a fixture design comes around that is so bad that we feel a special need to call attention to it. So here, for your viewing displeasure is our choice for the worst street light fixture design ever, The Acorn Light.
What makes this fixture so bad? Heck, you probably have seen these things all over the place, right? Well, for starters, the fixture provides absolutely no control over the light it emits. By this, I mean simply that light shines in all directions. Up, sideways and down. Now, since people walk and drive on the ground, down is a good place for a fixture to shine. However, since this fixture is completely made of glass (except for the socket and fixture support on the bottom), more light actually shines up than down. Is this a problem you might be wondering? Well, yes, a critical problem. Since most of the light shines up, this fixture is consuming twice as much energy as a properly designed fixture would need to consume to put the same amount of light on the ground. This uplight directly contributes to light pollution in our communities. Light pollution is that sickly orange glow that we see over our cities and towns. Light pollution is the reason that most Americans (and others throughout the developed world) see only a few stars in the night sky. Light pollution (according to the International Dark Sky Association), wastes over $10 billion annually. Light pollution also harms wildlife and has been linked to some serious human health issues (including breast cancer).
This light also sends a significant portion of the light it produces sideways. Light sent sideways is better known as glare, since it shines into the eyes of drivers and pedestrians. Glare is never good. Glare reduces our ability to see at night (the reason for installing outdoor lights in the first place). Light shining sideways also crosses property lines, shining into windows and making it hard for those living in the area to sleep at night. Light that crosses property lines is referred to as light trespass. Light trespass is being dealt with in more and more lighting ordinances nationwide.
So, as you can see, this street light has it all. Energy waste, light pollution, glare, light trespass, reduced visibility. If one of your elected officials comes up with the bright idea of installing street lights in your neighborhood. Be sure that these ‘decorative’ glare bombs are not chosen. You’ll have to live with their poor performance for many years to come.
If you already have these obnoxious fixtures in your area, fear not. There are some cost effective things that can be done. First up, light shields are available for many of these fixtures. Light shields are typically metal housings that surround the light source on the top and sides, allowing light to escape towards the ground only. You won’t get all the energy efficiency of a properly designed fixture, but at least you’ll get rid of the most environmentally damaging aspects of these fixtures. Checkout the accompanying image. It shows how a ’sag lens’ cobra fixture was made into a full cutoff (downlight only) fixture with the application of one of the available light shields.
Yes, the acorn is the award winner (winner doesn’t sound like the right word to me though) for worst streetlight.
There are some acorns in a city near to Palomar that is switching to white light. White by itself is not good for astronomy. White light shining directly up into the sky is even worse. Do you have recommendations for shields that can be added into the acorns?
While that clearly is a bad lighting design that ought to be banned, there are even worse and more wasteful lighting practices than acorn lights. Here in Germany for instance, there is this new craze of putting upward-shining lamps into the ground, creating a ray of light that goes directly up into the sky. A fixture, that sees to serve no useful lighting purpose at all:
http://www.scienceblogs.de/frischer-wind/2009/02/bodenleuchten-und-die-lichtverschmutzung.php
Unfortunately, these ground lights have been popping up all over the place in recent years (and yes, we still have a lot of these acorn lights around here as well…).
Scott. a San Diego city official told me that there is some kind of ordnance requiring low pressure sodium lamps to be used within 30 miles of Mt. Palomar. That narrow spectrum line should be relatively easy for Palomar to cope with
Tom,
At this time, it seems that the city of Carlsbad, CA is contemplating a move from High Pressure Sodium (HPS) lights to a whiter induction lamp. This broad spectrum lamp would be near impossible to filter out and would severely harm observations at Palomar. They’re supposedly going to use a full cutoff (downlight) fixture and hopefully make use of lower wattages and, ideally, dimming. We can only hope for the best at this time.
Anthony
Anthony, here is the San Diego Municipal Code 142.0740e(2):
Outdoor lighting used for security purposes or to illuminate walkways,
roadways, equipment years, and parking lots may remain lighted after
11:00P.M. where the lighting meets the following criteria:
(A) Where located within 30 miles of the Palomar Observatory or
Mount Laguna Observatory, lighting fixtures below 4,050
lumens are permitted. Lighting fixtures above 4,050 lumens
shall be limited to low pressure sodium or high pressure
sodium and equipped with full cut-off optics (fixtures with
flat lenses that limit lamination to below the horizontal plane
of the fixture or 0 percent up-light). Where high pressure
sodium lighting fixtures are proposed, a photometric study or
lighting power density calculation of ground lighting levels
shall be required to demonstrate that a 3-footcandle or 0.19
watts per square foot average will not be exceeded.
(B) Where located 30 miles or more from the Palomar
Observatory or Mount Laguna Observatory, lighting fixtures
below 4,050 lumens are permitted. Lighting fixtures above
4,050 lumens shall be limited to low pressure sodium or high
pressure sodium and equipped with cut-off optics (fixtures
that limit illumination to less than 2.5 percent up-light).
Actually there is one that is worse. It’s an acorn with an internal refractor over the bare bulb.
Mosts acorns are of this type. The refractor directs some of the light just above 90 degrees downward into the glare zone. See my “Acorns are Nuts!” at
Most are generally 100-150 watts. However, I understand that NYC has some of these at 400 watts metal halide around Penn Central RR station.
Perhaps worse yet is when they growing 4-5 on a pole which can be seen in the photo section of my web site There is also a picture of one with one side completely black out, because it was blowing the neighbors out of the house, and there were
others in the same area. Hello!
And how about this:
http://www.washingtonpost.com/wp-dyn/content/article/2008/04/30/AR2008043003532.html
Best article yet that tells more about what it is really like! LIGHTING HELL!!!
These are the worst lights, but unfortunately cities and towns throught my area think these “antique” lamp posts are the greatest things and are putting them up in the town centers. Sure they look great on post-card snapshots taken on a Sunday morning, but once night falls, these things are utterly useless. My town just put up about 2 dozen more of these things in the last week. I’m writing a letter now explaining why they are bad, hopefully the powers that be will get it and consider different fixtures next time a lighting upgrade is in order.
Hey Jim
Along with the usual points of light pollution, energy waste, global warming, etc, you might want to mention the recent news linking excessive night time illumination with various forms of cancer.
Typically, municipalities have felt that it was always safer to err on the side of over illumination. They figured that they’d be less likely to get sued if it was too bright than if it was not bright enough (or could even be argued as such by an attorney.
However, with the link now firmly established between excessive night time illumination and various forms of cancer, you might drop the comment in their ear, that since they now know about that, city councils could be opening themselves up to future litigation for installing too much or too bright outdoor lighting.
And, as I always do, I’d finish by mentioning that you’re supporting dark skies… not dark streets. They should admit their mistake and move on, while they only have 2 dozen bad lights to replace.
Anthony