Joen­suu switc­hes to smart out­door ligh­ting

City ligh­ting is success­ful when resi­dents don’t pay any atten­tion to it, Joen­suu city engi­neer Tero Toi­va­nen and con­struc­tion mana­ger Jan­ne Ket­tu­nen say.

The city of Joen­suu has 22,000 out­door lights, and until now they have had one cont­rol sys­tem. Accor­ding to Toi­va­nen, the old sys­tem was more than ten years old and at the end of its milea­ge.

The switch to the intel­li­gent out­door ligh­ting cont­rol sys­tem was comple­ted in Joen­suu at the end of 2023.

The­re are now around 300 street light cen­ters around the city, and behind one cen­ter the­re are an ave­ra­ge of 70 street lights.

Error noti­fica­tion in real time

If the­re is an error in one of the cen­ters, it will be noti­fied imme­dia­te­ly.

Toi­va­nen says that even though the new ligh­ting sys­tem in Joen­suu is able to indica­te qui­te preci­se­ly the point whe­re the light does not light up or if it lights are on too long, the­re are tens of thousands of human sen­sors in the city that report this.

– A town resi­dent cal­led to say that the light has been off for a couple of days, isn’t the­re any­one going around and loo­king, Toi­va­nen laughs.

– I answe­red him that we have 78,000 super­vi­sors in the city. So the city does not have to use resources to moni­tor the street lights thanks to the awa­ke­ned resi­dents.

– Ligh­ting is a surpri­singly sen­si­ti­ve and inte­res­ting thing, adds Toi­va­nen.

Now we can see direct­ly from the sys­tem whe­re the error is and defi­ne the loca­tion.

After the ini­tial fine-tuning, the new sys­tem has alrea­dy pro­ven its effec­ti­ve­ness, accor­ding to Jan­ne Ket­tu­nen.

– Now we can see direct­ly from the sys­tem whe­re the fault is and defi­ne the loca­tion.

Pre­vious­ly, you had to go through the sys­tem to see if somet­hing was wrong. In the old sys­tem, for example, the­re was no noti­fica­tion of dis­tur­bances in ligh­ting cen­ters, now it noti­fies the exact loca­tion.

The price of elect­rici­ty sparks discus­sion

Tero Toi­va­nen says that main­te­nance and moni­to­ring of the city’s out­door ligh­ting is now pos­sible remo­te­ly. Thanks to the new sys­tem, it would even be pos­sible to cont­rol the lamps indi­vi­dual­ly if neces­sa­ry. And most impor­tant­ly, ener­gy efficiency impro­ved even more.

– LEDs con­su­me one third com­pa­red to tra­di­tio­nal lights, Toi­va­nen explains.

– Howe­ver, the ener­gy saving in renewing the ligh­ting sys­tem is not as great as it was when switc­hing to LED lights a good ten years ago.

In recent years, the price of elect­rici­ty has spar­ked discus­sion among the people of Joen­suu.

– When the elect­rici­ty price inc­rea­sed rapid­ly, you noticed it in the amount of feed­back from resi­dents. If a light was on somew­he­re during the day, the­re was imme­dia­te feed­back, Jan­ne Ket­tu­nen says.

Thanks to modern light tech­no­lo­gy, the cost of sea­so­nal lights, for example, is very low.

– We got a feed­back about Christ­mas lights that it was a was­te of elect­rici­ty. The year­ly expen­se of Christ­mas ligh­ting is about 1,500 euros.

The city of Joen­suu has been using ener­gy-efficient LED lights for ten years.

Savings are calcu­la­ted in time, not money

Surpri­singly, the new ligh­ting sys­tem does not bring much savings, because, accor­ding to Tero Toi­va­nen, the city has alrea­dy ins­tal­led LEDs for ten years. But if time is money, the city will save a lot com­pa­red to befo­re.

– Ener­gy con­sump­tion star­ted to drop sig­ni­ficant­ly alrea­dy ten years ago when switc­hing to LEDs. Now 87 percent of all city lights are LEDs.

– The new ligh­ting sys­tem has no effect on con­sump­tion, but we can cont­rol the ligh­ting times and see the ener­gy con­sump­tion.

Even so, the idea that street lights bur­ning all night is a was­te of money still lives on among some city dwel­lers.

Accor­ding to Tero Toi­va­nen, the bene­fit from ligh­ting is grea­ter than the money spent on it. At the time of the old light tech­no­lo­gy, even Joen­suu used night extin­guis­hing, when part of the urban envi­ron­ment was dark in the midd­le of the city.

– Lights are an impor­tant safe­ty fac­tor. Dark­ness is percei­ved as unsa­fe in the city.

The best ligh­ting is unobt­rusi­ve

Accor­ding to Toi­va­nen and Ket­tu­nen, the best ligh­ting in the city is the kind that the city dwel­lers don’t even notice.

– All new lights have a dim­ming pro­fi­le and in qui­et times the light out­put is reduced by half, the human eye doesn’t even notice it, Toi­va­nen knows.

Even though LEDs con­su­me a litt­le elect­rici­ty, even that litt­le con­sump­tion is hal­ved at night.

– And from the end of May to the end of July, all the lights are tur­ned off at night, except for the city cen­ter.

Jan­ne Ket­tu­nen says that the lights turn on and off accor­ding to the twi­light sen­sors.

– The sen­sors stu­dy the bright­ness and dark­ness of the weat­her. They don’t react to fog, alt­hough if it’s dark enough, even to that.

Accor­ding to Toi­va­nen, dif­fe­rent sen­sors and meters can also be ins­tal­led in the new street lights.

–A lamp-speci­fic air qua­li­ty or noi­se meter could be pos­sible in the futu­re. It has not yet been seen neces­sa­ry to ins­tall such, but tech­no­lo­gy would make it pos­sible.