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Intelligent street light system uses 80 percent less electricity


July 12, 2011

An experimental energy-saving streetlight system automatically dims the lights when no people or moving vehicles are in the area (Image: TU Delft)

An experimental energy-saving streetlight system automatically dims the lights when no people or moving vehicles are in the area (Image: TU Delft)

Of all the energy-saving tips out there, probably the one we hear most often is to not leave lights on when we leave a room. It's good advice, yet cities around the world are not following it in one key way - their streetlights stay on all night long, even when no one is on the street. The Netherlands' Delft University of Technology is experimenting with a new streetlight system on its campus, however, in which motion sensor-equipped streetlights dim to 20 percent power when no people or moving vehicles are near them. The system is said to reduce energy consumption and CO2 emissions by up to 80 percent, plus it lowers maintenance costs and reduces light pollution.

Delft Management of Technology alumnus Chintan Shah designed the system, which can be added to any dimmable streetlight. The illumination comes from LED bulbs, which are triggered by motion sensors. As a person or car approaches, their movement is detected by the closest streetlight, and its output goes up to 100 percent. Because the lights are all wirelessly linked to one another, the surrounding lights also come on, and only go back down to 20 percent once the commuter has passed through. This essentially creates a "pool of light" that precedes and follows people wherever they go, so any thugs lurking in the area should be clearly visible well in advance.

The lights' wireless communications system also allows them to automatically notify a central control room when failures (such as burnt-out bulbs) occur. This should make maintenance much simpler, as crews will know exactly where to go, and when.

Some fine-tuning is still ongoing, in order to keep the lights from being activated by things like swaying branches or wandering cats. In the meantime, Shah has formed a spin-off company named Tvilight to market the Delft technology. He claims that municipalities utilizing the system should see it paying for itself within three to four years of use.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

It\'s a nice project, I remember the TU/e (University of Technology Eindhoven, Netherlands) is also doing the same kind of project on intelligent street lighting. I\'m not sure about the ready-for-market status, but here\'s the link anyway. http://www.tue.nl/onderzoek/instituten-groepen-scholen/top-research-groups/intelligent-lighting-institute/research-programs/roadlighting-2015/

Roy van den Heuvel

I love this idea!

Carlos Grados

Well it\'s an excellent idea to the usual \"Oh Duh\" kind of broad ranging, bad, and wasteful habits.

Mr Stiffy

It\'s a great idea. The only downside is that most streetlights use high-pressure sodium bulbs, which need about 1-3 minutes to fully light up. The ignitor uses a 3-5kw spark, which would be pretty bad for the grid. So, I guess the project initiators use a different kind of bulb - what about the bulb\'s efficiency?

Renārs Grebežs

As a start . . this would be a great idea for our local school systems . . the electric utilities should be made to install these in every school parking lot . . of course the savings would pay for the equipment . . so the utilities would break even while not having to provide for extra capacity and our school boards would reduce the lighting bill . . . and hopefully pass on the savings in lower property taxes.


Reminds me of trying to walk past the houses of security-mad people with sensor operated lights where I used to live. It made walking the dog unbearable as you were constantly assaulted by lights illuminating as you passed. It was like being on stage with a follow spot trained on you. It also ruined your night vision for about fifteen minutes each time one went on.

A highly unpleasant idea. Do what I do in the countryside: buy a torch for about one pound/euro/dollar and take it with you. Cheap and cheerful, saves the planet and works fine. Street lighting is of more use to criminals than anyone else anyway.

Doug MacLeod

Street lights around here (South-East Wisconsin) have started to convert to LED rather than the sodium bulbs.


Los Angeles is changing over all street lighting to LEDs. The one in front of my house is almost too bright, so I\'d be all for this. They say they\'re working out problems of cats, branches, etc., but I wonder about prowlers movements.


Excellent idea. Its already in use at a much more basic level in our apartment. We have motion sensors to activate a 22W CFL in floor lobbies on all floors and staircase. In the absense of any motion, when the 22W CFL is OFF, a 5W CFL is always lit up.

Prior to this energy saving setup, we had 2x22W CFL on all floors lobbies and staircase. These lights were switched-on at 6:00pm and switched-off at 6:00am daily. Considering that people movement is present between 6:00pm to 12 midnight max, we end up saving considerably. Since LED lights were very expensive, CFL were used.


It sounds like a good idea but I don\'t know if it is. What if a criminal should hide and remain still. The lights would dim and then the unsuspecting person might walk into a trap thinking that all was safe.

Adrian Akau

@Ren%u0101rs Grebe%u017Es - If you would have read the article, you would know that they talk about the lights being LED and not traditional Sodium or other compressed gas bulb. Tons of savings right there.

I believe that when the article states there being a 2-3 year timeline before system pays for itself is because all the current conventional lights will have to be removed and new LED lights (and associated network hardware/connections) have paid for themselves. In any case, I think this is such a good idea, I am forwarding this article to our City Manger and Services personnel to keep in mind come next budget talks (and if this tech matures...)

Edwin Wityshyn

Actually, if you look at efficiency, sodium vapor lights are very efficient, sometimes more than LEDS. So you don\'t neccesarily gain any savings there. The big advantage municipalities currently are interested in with LEDs is the very long life. The price of the bulbs along with the manpower to replace them makes LEDs attractive, plus if they use the same or less electricity, that helps sell them too.


Good idea. But I also agree that it is not a perfect solution use this way in the street lighting. It is much better if we just dim the HPS to a very low level (as 20~30%) and step up at once when needed. We ever developed several street lighting projects by wireless control. Of course, just replace the ballasts and use the old HPS lamp/fixtures, dimming up to 40%. Energy saving 60%.


its a nice idea

Sunil Sharma
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