Wigan weighs in: Blue spectrum LEDs too cool for residential streetlights

Wigan Council has confirmed our report from last week that it is abandoning blue-tinged LED luminaires in favour of warmer colour models, although it downplayed any possible health concerns it had for the colder lamps.

The borough will still use blueish LED lamps at 5,700 kelvin on busy traffic roads, but will prescribe warmer LEDs (a lower kelvin temperature) for residential areas, assistant director of infrastructure Mark Tilley said in an email, noting that Wigan is 'selecting appropriate (colour temperatures) for the different streetlighting installations across the borough.'

Wigan has already replaced about 5,500 streetlights in a three-year retrofit of 31,000 units. The first phase will continue with the colder temperature 5,700 K models, but Wigan will shift to a warmer

'CCT' (correlated colour temperature) when it moves into residential areas in the spring. Tilley wrote:

'The first phase of the project will target the replacement of the highest energy consuming lighting units. These are generally sited on traffic routes and the selected LED lighting solution will be of a CCT of 5,700K. We have not received any complaints or negative comments from residents regarding the use of 'cool' white LEDs for lights that are situated on traffic routes and this approach will not change.

'The next phases of the project, due to commence on site next April, will primarily target lighting installations sited on residential streets.

'Prior to commissioning the borough wide project, Wigan Council's street lighting team carried out a number of trial installations with LED lighting units with CCTs between 4,000 K and 6,200 K...Some feedback from residential areas did suggest the higher CCT gave a cool feel to the appearance of the street. We understand this response to be similar to other LED projects that have used “cool” white LEDs in similar circumstances and more recently there has been a technical debate around this issue for street lighting.'

Tilley did not specifically say which colour temperature Wigan will use. As Lux reported last week, Wigan Council told national campaigner Simon Nicholas that it would now deploy 4,000 K. Wigan had written to Nicholas after he expressed concerns about the LED retrofit, including possible harmful health effects from blue-tinged light such as sleep disruption and possible links to cancer.

'We are aware of some of the claims being made with regards to the potential impact on health of LEDs with rich blue light content,' Tilley told Lux. 'However, we are not aware of any of these claims being specifically linked to LEDs being used in street lighting applications but do understand that LEDs with a lower CCT have not been linked to these claims in the same way.'

Tilley also noted that warmer LEDs are significantly more efficient now than they were when Wigan first mapped out its LED retrofit with colder LEDs.

'Historically, the difference between cool white and neutral white LEDs in terms of energy consumption has been significant but more recently that difference has markedly decreased,' he said. 'Therefore, in terms of the energy consumption for the unit being supplied by Philips Lighting, there is likely to be only a nominal difference in the energy consumption of around 1 watt per unit.'

With that, perhaps more LED streetlighting projects will begin to warm up around the world, which has had mixed reactions to the energy saving technology.

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Photo is from plentyofants via Flickr