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How Helsinki puts humans at the centre of street lighting design

By intouch * posted 18-02-2019 13:31

  

It could be argued that few people have more reason to take illumination seriously than the Finns. In the depths of their icy winter months, the communities to the country’s north live in almost complete darkness some days of the year.


Screen_Shot_2019-02-18_at_12_59_59_pm.pngThat’s why it’s so surprising that more cities haven’t followed the City of Helsinki’s example and installed human-centric lighting. In fact, it’s believed to be the first installation of its type in the world.

Olli Markkanen, the City’s Head of Municipal Engineering, says the idea for ‘human-centric lighting’ came from a competition to design the general lighting in a new city district, located on the site of a former oil harbour. It is expected the area will be home to 12,500 Helsinki residents within a decade.

“In 2012, we had a competition for the general lighting in Kruunuvuorenranta. The aim was to build a new district of light. We had 52 lighting design companies from all over the world that participated in the competition. In the two winning proposals, one of the key points was that the colour temperature of the light is not constant but variable,” Markkanen says.

Human-centric lighting is a concept that’s been used in indoor lighting for years, but it’s only now that its principles are being applied to street lighting. Instead of using just one colour temperature for the whole night period, LED luminaires are controlled to move between cooler and warmer colour temperatures depending on the time of day, synchronising with humans’ natural body clocks.

“Human centric lighting is a way to illuminate white light with dynamic colour temperature to satisfy the customer needs,” Markkanen explains.

Screen_Shot_2019-02-18_at_1_30_03_pm.png“Daylight colour temperature is not constant – it varies by day and by season. It has already been used in indoor lighting. Warm light relaxes and cold activates. Studies have been carried out to illuminate a school classroom with cold light to activate the pupils – but if the cold light is used for too long, it makes the students restless and much too active.

“Well-known research has found that the human body has a 24 hour clock that controls all our functions. One key aspect is the control of the hormone Melatonin, which dictates our sleep patterns. To reset our body clock, researchers have found that blue light in the morning helps keep the clock set to 24 hour cycle.”

Markkanen says the true test of the technology, which was installed in August, will eventually be judged through a customer satisfaction survey. For the time being, however, he’s satisfied that the technology works.

“It is always a challenge to integrate lighting controls with luminaires. The control of different colour temperatures relative to the required lighting classes took time to consider the best way, as the different colour temperature LED chips have different lumen outputs, but it all works well now,” Markkanen says.

Markkanen will discuss the technical details of the project, including a live demonstration, at IPWEA’s 4th International Street Lighting and Smart Controls Conference, being held 2–4 April in Sydney.

He says there were a number of hurdles to overcome when the project began, not the least of which was the availability of the type of luminaires needed.

“At that time, we couldn’t get any luminaire manufacturer to build us a luminaire with variable colour temperature. It seemed that the idea of variable or dynamic colour temperature should be abandoned. But then I had an idea how to do this quite simply, without the need for any extra technology. In practice, it wasn't that easy, but we managed to solve the problems with our partners,” Markkanen says.

He says partnering with OrangeTek (an IPWEA SLSC technical advisory group supporter) was an integral part of the project’s success.

“We needed a good luminaire and a solid controlling system. Our system is the OrangeTek luminaire, together with the C2 SmartLight Central Management System from Finland,” Markkanen says.

“OrangeTek's approach to lighting is quite philosophical; perhaps that is why they dared to take my idea seriously and produce the luminaire.”

Markkanen expects to see many more human-centric lighting projects popping up.

“Lighting operators should understand the need to take customer needs seriously,” he says.
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