Environmental 21st Century Street Lighting – The Power of Dimming

Street light in Shaftsbury Ave, Westminster, London.
The LeafNut System installed in Shaftsbury Avenue, Westminster.

A revolution in street lighting is underway and with it comes huge savings of up to 50% in costs and carbon emissions.
Local municipal authorities worldwide are under a great deal of pressure to cut costs and reduce their carbon emissions to meet environmental targets. In January this year, the US government set greenhouse gas emission reduction targets of 17% by 2020, 30% by 2025, 42% by 2030 and 83% by 2050. As a result towns, cities and Local Municipalities are under pressure to reduce their carbon footprint and cut costs, but the opportunities available to them are not easy to find.
With around 35 million street lights in the US, consuming as much electricity as 1.4 million homes and generating greenhouse gases equal to 2 million cars, street lighting is one of the USA’s largest contributors to carbon emissions. Street lighting also accounts for 30-40% of a typical city’s energy budget, costing the US a total of $3.5 billion in electricity every year. As a result, many municipalities are looking at saving money and reaching their targets by switching off street lighting.
In the UK, where some municipalities have attempted to switch off street lighting completely, to save electricity costs, the general public has expressed genuine concern about public safety, crime prevention and road safety. Leaving areas in complete darkness will not be easily accepted, so local municipalities are being forced to look at alternatives.
In the US one state that is looking at introducing changes is Minnesota. In Rochester, the municipal authority is in the process of preparing to charge ‘streetlight fees’ as part of monthly utility bills. The fee will be $1.82 a month for most homeowners, whilst the fee for a large industrial business could be as much as $190.23 a month, based on the kilowatt usage. The fee would pay for the $1.3 million cost of Rochester’s 9,650 public street, trail and sidewalk lights.
In recent years, there have been a large number of energy-saving developments in lamp, ballast and central monitoring system technologies that have made it possible for companies to develop revolutionary energy-efficient street lighting systems, which can save municipal authorities significant amounts of money by enabling them to dim street lights, not switch them off completely.
One municipality that has done this is the City of Westminster, in London, UK. Like the US, municipalities in the UK have been set directives by Parliament to reduce carbon emissions by 60% by 2050 in comparison to 1990 levels.
At 40 years old, Westminster’s street lighting had become extremely inefficient. The municipality wanted a street lighting solution that could not only help it meet the carbon reduction targets set by Parliament but also save money and be easier to maintain. In particular, they wanted a solution that would enable its engineers to proactively and effectively manage individual or groups of lights by dimming lanterns at specific times and in certain locations.
Westminster chose a system that enables them to do just this. Targeting areas where street lights were serving little purpose at particular times, Harvard Engineering’s LeafNut system allows Westminster to reduce the lighting levels in specific locations whilst continuing to provide lighting to ‘hotspots’, such as areas where theatres and restaurants provide late night entertainment. Due to its flexibility, the LeafNut system also allows street lights to be turned back to full intensity at anytime, should it be necessary, with a few simple keystroke commands on a desktop, laptop or even iPhone.
Initially, crime was a major concern for people living in residential areas in Westminster, where, using the new system, street lights were dimmed by 25% during the early hours of the morning. They were concerned that should lights be dimmed, it would increase the chance of their homes being targeted by criminals. However, due to the reduction in brightness being barely visible to the naked eye, the initial concerns proved inaccurate.
Since the deployment of the new system, Westminster has achieved initial cost savings of 30% in its energy bills, as well as a significant reduction in the carbon emissions produced from its lighting infrastructure.
Dave Franks, chief lighting engineer at Westminster Municipality commented when the system was first deployed,

“I believe that LeafNut has the potential to change street lighting as we know it. I am extremely excited about it and the benefits it can bring to the City of Westminster.”

If a system, such as LeafNut, were to be deployed across all 35 million of the US’s street lights, the system would help save up to 3.8 million tons of carbon emissions every year and $2.1 billion.
Harvard Engineering, the company behind the LeafNut system, has a commercial relationship with Venture Lighting in the US.

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