Saving Energy in Street Lighting is Crucial Today
The first city streets to be lit in the U.S. are thought to be Philadelphia where it was introduced by Benjamin Franklin who was a Postmaster at the time.
Even back then, there was a concern for efficient lighting Candles placed inside glass containers were lit at twilight. The containers were to keep the breeze from extinguishing candles but the glass was easily broken.
Franklin designed a four sided enclosure for the sake of finances and efficiency. With four glass panes, the glass enclosure would not be useless if broken as only the pane which broke would need to be replaced.
In the early 1800s, the invention of gas light was used in Baltimore. The new gas lighting spread across the cities of the country and in some places, there are still towns that use gas to light city streets at night.
Fangled Electric Lights
Two generations later Wabash, Indiana was the test city for new fangled electric lights. Cities began to switch to both fluorescent and incandescent light bulbs for street lighting.
The move was a logical one as the fire of gas lights posed a safety risk in cities where buildings were mainly wooden in construction.
Street lighting was an amazing thing in the 1800s. Today you will still hear Broadway in New York referred to as the Great White Way but few people realize that nickname was a result of the high number of lights on theater marquees along that popular street.
There were many forms of street lighting used over the years. Often the choice was made based on local materials available, on fuels available and on the money available to spend. When electric street lights became commonplace there were quite a few varieties used such as:
- Arc Lamp - very bright lights used in major cities. Arc lamps were placed on very high towers and required considerable maintenance. Also used for stage productions and especially for lighthouses.
- Incandescent Light - These were the first low power electric lights used worldwide. Some are still in use in various cities but most have been replaced with more efficient CFL bulbs. These are lights used in city districts striving to give a historical appearance.
- Fluorescent bulb - Introduced in the 1930s this bulb uses a small current to create a light that appears in the gas inside the bulb. This glow is weak in visible light but is strong in ultraviolet light.
- Mercury Vapor - In the late 1940's, mercury vapor gained popularity rapidly because it was bright than either fluorescent or incandescent street lighting.
The bluish cast of the light was not flattering to skin tones and the bulbs gradually become dimmer with age. Newer versions of mercury vapor lights in the 1960's solved some of the problems by adding a coating of a phosphorous material.
These later lamps were labeled "color corrected". The sale of mercury vapor light was banned in the U.S. in 2008 under the Energy Policy Act of 2005 but bulbs can be purchased for existing lamps.
- Metal Halide - Use in recent years, metal halide lighting is good for business installations and often found in large warehouses, schools, hospitals and office buildings.
- Compact Fluorescent Lamp - These are used more today as the quality has improved. Good for use along walkways and for city street lighting but are not as reliable as they might be. A major problem is heat buildup in the lamp.
- Light Emitting Diodes - This lighting has almost replace fluorescent and incandescent lighting for crossing signs and traffic signals. The cost of LED lighting is high which continue to limit its use as street lighting.
Cost is the Motivation
Our city streets would be dark and dangerous with the street lighting we've come to depend on. In many cities today there is a new focus on energy savings in street lighting.
Though environmental concerns are usually mentioned the biggest motivating factor is saving money.
Cities are strapped for operating cash these days and help from state and federal governments is hard to find in a struggling economy. Street lighting can be a huge part of a city's operating budget.
The energy needed to power street lighting is often the third largest power use by a local government and may account for from 10%-35% of the total electric bill of the town.
On a national level there are about 35 million streets light in the country. Those lights represent about one percent of all the electricity used in the U.S.
The type of street lighting used is the biggest part of the problem. Old installations have not been upgraded or replaced due to financial constraints. Much of the country has high intensity discharge fixtures lighting bridges and highways.
Like other lights commonly used in the past, HID fixtures are not energy savers or particularly efficient. Many of the bulbs of various types used also contribute to the problems in our landfills.
Street lighting energy is gaining renewed attention today as we move consistently toward use of renewable energy resources and look for more environmentally friends way to lead our lives.