StreetLightNews

The Worcester Telegram & Gazette reports that the city council of Fitchburg, Massachusetts plans to eliminate many street lights in an effort to save money. The suggestions so far propose that either one in four street lights be turned off, or the street lights should be turned on at major intersections, and shut off at half of the remaining fixtures. No suggestion related to dimming was allegedly discussed during the meetings.

The benefits of dimming are clear and well-documented. Companies offering solutions in street light management can generate energy savings of 25-40 percent through dimming and more exact burn hours. Such a solution can typically be installed in every pole or simply in the control cabinets, the latter being the most cost-friendly solution. Therefore, dimming would be a great alternative to the suggested solutions in Fitchburg, which in practice would mean that all lights can be left turned on, thus maximizing a high level of safety for the citizens while saving energy and money at the same time.

In a time where a sustainable environment is on top of the agenda, it is crucial that we all have a common understanding of how technology can contribute to a better environment. With street lighting in mind, it is therefore troubling to find that there is still confusion about the benefits of dimming.

In an article brought in The Press on 16 October 2008, the author, a York-resident, expresses his sincere doubts about how dimming can save energy, thus money. He argues that if he turns his dimmer on at home, he will still be charged the same amount as without a dimmer. Several comments follow from different readers trying to explain the correlation between the consumption of kilowatt-hours and dimming, stating that the author is completely wrong.

However, there is some truth in his claim. Provided that he refers to a standard incandescent light bulb with a traditional home-installed dimmer, the savings in his house would be minimal. Such an installation simply cannot be compared to dimmed street lights as these typically use high pressure sodium (HPS) bulbs and a different dimming system. When lowering the voltage on a HPS bulb during off-peak traffic hours for example, the wattage will decrease by 25-40 percent. The point here is, that you cannot compare traditional incandescent light bulbs in your living room with high pressure sodium bulbs used in street lights in terms of dimming.

The town of Lac Megantic is home to Canada’s largest telescope. However, due to population growth and urban sprawl in the surrounding area, conducting research at the observatory was becoming increasingly difficult.
Therefore, an initiative to reduce the sky glow has led to installation of a number of dimming units in streetlight poles. During the hours of 10 pm and 6 am, the streetlight is reduced by up to 65%, saving as much as 50% energy.
The solution, Night-Saver, is controlled via a microchip and is installed in individual poles. Read more about the project in Canada here…

A recent article in Washington Post describes how streetlights are a significant source of greenhouse gas emissions. The newspaper quotes Robert Grow, director of government relations at the Greater Washington Board of Trade, for estimating an annual reduction of 1.2 million metric tons of carbon dioxide emissions if the 10 largest metropolitan areas of the US switch to a centralized solution and LED streetlights. This is equivalent to taking 212,000 cars off the roads and save an additional 90 million taxpayer dollars annually.

In his report on streetlight savings, Grow recommends a centrally controlled streetlight solution with dimming and optimized maintenance functionalities.

According to the Post, Grow was surprised that more hasn’t been done already to improve the efficieincy of streetlight.

As previously described in this blog, the most efforts have been made in the town of Ann arbor, Mich. where all streetlights have been converted to LEDs.

Centralized streetlight solutions are offered by companies such as US-based Echelon with installations in e.g. Oslo, Norway, and Danish company Amplex with installations in e.g. Scandinavia, the United Arab Emirates and Asia.

According to Gordon Brown’s clima speech last week, the UK has plans of creating an environmentally sustainable economy. They have passed a law to fight global warming and want to lead the way by becoming the world’s leading green nation.

According to Brown, the government is currently considering whether the targets for CO2 reductions can be increased from 60 to 80%.

Also, the UK strives to achieve the EU target of having 30% of all energy coming from sustainable energy sources in 2020. Additionally, the financial support for sustainable initiatives will be increased significantly.

In Devon and Cornwall, they have already commenced serious preparations for sustanability by launching a project where all street lights will be dimmable. 40% of the region’s CO2 emmissions stem from lighting, and thus lowering the energy consumption here will provide significant CO2 savings. 

In a New Yorker article, David Owen describes how dark skies are increasingly difficult to find. He states that most Americans are unable to see the Milky Way where they live. Obviously, the stars have not become dimmer, but excess light increasingly prevents us from seing the entire beauty of the skies at night.
According to Bortle’s Dark-Sky Scale, invented by John E. Bortle in 2001, nighttime skies rated 1 are as dark as in Galileo’s time. At the other end of the scale is New York with a dark-sky rating of 9.
But there are several ways of avoiding, or at least minimizing, the light pollution from urbanized areas. Naturally, improved street lights are a big factor in reducing the excess light. Not only through retrofitting the luminaires and bulbs, but also by controlling that the lights are turned off and posibly dimmed at the most optimal times. For more information on centralized control and dimming, see e.g. www.amplex.dk or www.streetlight-vision.com.
To read an abstract of the New Yorker-article, click here…

Lighting up a city’s streets is typically the single most significant energy expenditure of the city. And only few areas require the same amount of maintenance and operation resources.
With centralized control, savings of 8-10% can be achieved, but the real savings occur when the city switches to dimming. Studies and numerous experiences show that savings of 30% and above are reached, giving a pay back time of just a few years.
Follow this link to learn more about dimming technologies by e.g. power reduction and electronic ballasts.

The Danish company, Amplex, has released a report stating that savings of 25-30% have been achieved by centralizing street light control in a major Turkish city.
The report describes a pilot project where modules are installed in five control cabinets at representative locations in the city. Parts of the savings come from centralizing control, but the most significant savings are generated through dimming at off-peak hours. Two dim levels were established, and the lights went back full on early in the morning.
Even though the pilot showed savings of up to 32%, Amplex expects the savings to be even bigger when burn hours are optimized and when dimming is set earlier in e.g. industrial areas and on weekends. Additionally, savings are expected on maintenance and proactive bulb change. Based on the indications from the pilot, a very low ROI of 1-2 years can be expected.
Read the full executive report here…

In order to increase the safety of night-time driving on UK motorways, and additionally lower CO2 emissions, the Lancashire County Council decided to equip a stretch of motorway M65 with a dimmable lighting system controlled by traffic flow. The system can be dimmed with up to 30%, and is equipped with an intelligent controller and a two-way remote communication facility. Additionally, it offers individual control of luminaires, event reports and constant monitoring functions of the installation.
The project came about when lighting fixtures at a specific stretch of the motorway had to be renewed. The previous installation was controlled by photocells mounted at each feeder pillar, switching the lights on and off through a contactor. The lighting levels were constant throughout the night. The luminaires in the old installation were also emitting excess light beyond the boundaries of the highway, contributing to light pollution in the surrounding area.A replacement plan was implemented in order to link the lighting level to the traffic flow, reduce the power consumption and to monitor possible lamp defects.
Through already existing traffic counters which continuously monitor the amount of cars on the motorway, the lighting levels are adjusted to preset levels depending on the traffic flow.With more than 3,000 cars per hour, the lighting level was kept full on. With 1,500 to 3,000 cars per hour, the lights were dimmed to 75, and with less than 1,500 cars, lights were dimmed to 50%.
The new luminaires allow for ‘soft’ switching when shifting from one level to another, avoiding sudden changes in the lighting levels. Additionally, traffic safety is judged to be increased because dimming, opposed to e.g. turning off every other light as a savings measure, provides protection from a flickering or strobing effect.The completed pilot has shown that not only has the stretch of motorway gained better lighting quality and improved control, CO2 emissions are lowered 274 tons to 129 tons through a combination of the dimming, traffic flow control and the new luminaires. Read more here…

In Warwickshire County, UK, the local newspaper reported last year that parts of the county’s street lights would be switched off in the early morning hours in order to save money. The county’s annual street lighting bill of £1.5 million could be reduced by £650,000, and this has sparked excitement among local politicians because the savings can be measured immediately. But the full switch off has resulted in protests from local inhabitants who believe that it will reduce street safety and lead to an increase in crime.
The debate has caused the county to support a proposal for a dimming pilot project instead of the full switch off. Comments from the councillors were mixed and revealed a great deal of scepticism. A Warwickshire council spokesman is quoted for saying that the cost of installing and operating a dimming system will be greater than any reduction in energy costs, but does state that this will change if the process becomes widely used.
Though the solution may be new in some areas, it is very widespread in others, and can be solidly backed by several years of excellent results, significant savings and return on investment of 1-2 years. Dimming solutions do have an initial cost, but this will quickly be outweighed by the savings on electricity and maintenance – without significant reductions in the street light quality. It seems bizarre that there are still serious considerations about lowering the street light quality through complete switch off when there are an abundance of intelligent street light providers offering well-tested and mature technologies.