Controlling the output of LED streetlights

Local and international street lighting fixtures have been steadily transitioning from halogen to LED lights. This initial rollout has allowed councils to experience varying lighting temperatures within a contained residential environment, gauge the community’s response, and better adjust to the needs of residents through trial and error.

When initially launched in the United States in 2006, bright ‘blue’ lights faced serious backlash due to their harsh nature in comparison to previous street lighting. Now, municipalities have adjusted colour temperature and improved the way they serve their citizens.

Along the west coast of the United States, the City of Los Angeles has 30,000 Philip City Touch units that monitor the operational status of streetlights, explained Kerney R Marine, Assistant Director of LA’s Bureau of Street Lighting. Although still in the testing phase of smart city technologies, the fixtures possess monitoring capabilities and the ability to remotely increase and decrease the illumination levels.

Marine explained that in terms of current LED conversions in LA, designs have been based on the IESNA recommended illumination levels. While LA does not currently dim streetlights below those recommended levels, they are investigating the possibility of doing so through their local utility, LA Department of Water & Power, during power-saving and/or emergency situations.

Marine will explore this topic at the 2019 Australian Smart Lighting Summit, the annual event for urban, outdoor, public and street lighting. Held from 28–29 August at the Melbourne Convention & Exhibition Centre, the event will feature over 35 Australian and international speakers and attract more than 200 attendees.

Exploring the effects of ‘overly bright’ LED street lighting on drivers at night and within residential areas, Dr Gillian Isoardi, Lighting Scientist at Light Naturally, and Professor Joanne Wood, Faculty of Health, School – Optometry and Vision Science at QUT, will discuss the overarching concerns of installing new fixtures.

They identify three key areas that must be addressed when designing and installing LED road and residential lighting:

• Too much light directed towards the view of road users (including drivers) — “Excessive light in the field of view can cause glare, which either reduces or degrades visual function (disability glare) as a result of the light scatter or can result in symptoms of discomfort and distraction (discomfort glare) but don’t affect vision,” said Isoardi and Wood.
• Too much light in the wrong direction, away from the street and towards residential areas — This is often termed ‘obtrusive light’ and has the tendency to interrupt people’s lifestyles within their homes; however, this is not limited to LED lighting. The speakers note that it is important to recognise “that obtrusive light can occur with any street lighting technology, regardless of whether it is LED or a conventional street light source”.
• Too much light in the wrong colour — This “can have negative environmental impacts”, Isoardi and Wood explained. When lighting near environmentally sensitive areas, “careful consideration is required of both spectrum and intensity”; however, “this is true for all light sources, regardless of whether they are LED or conventional sources”.

Marine, Isoardi and Wood will present at the 7th Annual Australian Smart Lighting Summit later this year in Melbourne.