The cost of any lighting system has the flowing components

1)    Material cost of bulb, poles and electrical wires and labor cost of installing the light – the cost of installing one street light pole is generally around $ 4000. It depends on the height of the pole, the rated power and efficiency of the light, type of foundation needed and length of wiring from the nearest source of electricity. When the nearest source of electricity is too far away as in rural communities it may be prudent to install solar powered street lights instead of laying down miles of wire to energize the light.

2)    Cost of energy consumed by the bulb – Our LED Street light consumes 80 watts and produces 5600 lumens of high quality light. By comparison the 209,000 street lights of Los Angeles use 197,000,000 kWh of electricity every year at the rate of 250 watts per hour. Cost savings in electricity costs by adapting the LED alternative is what is propelling Los Angeles and many other cities towards LED systems.

Added to this is the fact that LPS lights that produce the most light per watt have a Color Rendering Index (CRI) of ‘ZERO’. For good visibility they need to be combined with incandescent bulbs. The 5% efficiency rating of incandescent bulbs pulls down the efficiency of LPS lights as well. LPS lights are thus not suited for general purpose street lighting. 

The function of providing security is compromised with lights with low CRI. Police forces dislike low CRI lights because they make it impossible to tell colors apart. Yellow is the only color that is reflected. If an object does not reflect yellow light it appears black. Disruptions in the road are also difficult to visualize because the road and the dents all appear yellow! Poor contrast and color rendering necessitate that more powerful lights are needed to achieve the objectives of street lighting. Powerful lights in turn lead to glare which again compromises the ability of the human eye to see objects clearly. Indeed in areas where security is important mercury and metal halide lamps are preferred despite their inefficiencies and are rapidly being replaced by LED lights that cost a fraction to operate and maintain.

A comparison of good CRI lights shows that lights offered by MyLEDlightingguide.com outperform the others by a wide margin on all parameters.
 

3)    Cost of replacing burnt out bulbs and disposal of bulbs – We may not realize it but the cost of monitoring and replacing bulbs can be very high for street lights. Los Angeles spends 42 million dollars for monitoring and maintaining 209,000 street lights. This works out to more than $ 200 per street light per year.  The reason for the high cost is that street lights are placed at a height that necessitates the use of a cherry picker to carry workers to the light and a U haul truck to carry the cherry picker. Christian B. Luginbuhl of the U.S. Naval Observatory Flagstaff Station carried out a detailed comparison of different outdoor light options and concluded that LPS lamps last 6000 hours less than HPS lamps leading to higher maintenance costs. Besides ‘zero’ color rendering ability, this is an important reason why LPS lights have not become widely accepted.

Cost of replacing one bulb = Cost of replacement bulb + Salary of 2 people + rental of cherry picker + rental of U haul truck = $ 800 (Assuming cost of one bulb to be $ 150).

*All cost calculations are based on the data of US cities and reports by residents who have to pay directly for the replacement of street light bulbs.

Cities have found that funds available for maintenance have been frozen while expectations of service quality remain unchanged. Technology offers the only way out of the dilemma. Remote monitoring systems pare the cost of physical verification of lights while LED technology has extended the life of each light to 12 to 15 years from the current 5 years. The city of Ann Arbor had estimated that the savings in maintenance costs are higher than the savings in energy.

4)    Environmental impact of lights – The first 3 are easy to estimate while the fourth is not. Carbon dioxide emissions, mercury and heavy metal release in the environment, cost of treating water, land and light pollution, impact on ecosystems and human health- the ramifications of the lighting decision are manifold and covering all of them here is not possible. Suffice it to say that on all of these parameters LED lighting systems outperform all others.