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LED Streetlighting Must Be a Cool Colour Temperature


We know that LED lighting offers exceptional visibility, has a low carbon footprint, is cost effective and highly efficient. It’s perfect for commercial, industrial, domestic, indoor and outdoor applications and can handle extreme weather.

We have also learned that the cooler colour temperatures, 3000K (Kelvin) or below, are less harmful to humans, wildlife and the environment.

If your community LED streetlighting is above 3000K there is a high probability that sleep patterns, eye health and overall wellbeing are disrupted. This is obviously not desirable. The American Medical Authority has issued a policy statement confirming that it is in favour of LED streetlighting but recommends that cooler colour temperatures are utilised.

Specialist UK LED lighting companies like LED by Vision are countering any negatives with positive design and technology developments so that shielding, dimming and community friendly, safety enhancing LED lighting can be provided during the dark hours without impacting on communities.

The science bit

Going back to basics, wood and candles burn at 1800K with minimal levels of blue.

High consumption and costly incandescent bulbs possess a colour temperature of 2400K and feature more yellow and red than blue light.

Think in terms of appearance to us rather than in brightness.

CT is a measurement of the spectral content of light from a source, how much blue, green, yellow and red are present.

The CCT or correlated colour temperature alters the spectral content to the colour sensitivity of human vision.

Why is this important when selecting LED streetlighting?

The Circadian Principle. Humans have evolved so that when we see blue light the central nervous system is primed to wake up, it acts a stimulant.

A high-level CT means more blue content and the whiter that the light appears to us.

So, a white LED streetlight at CT 4000K or 5000K has high levels of short wavelength blue light and this appears to us as stark white. This is often too severe and results in an uncomfortable glare which affects vision because there is pupillary constriction and this compromises safety.

White LED lighting suppresses melatonin in humans by up to five times. Melatonin is the sleep hormone.

Blue light is distributed in shorter wavelengths than its yellow and red counterparts and it may damage the retina.

Several U.S. communities have successfully had their LED streetlighting reinstalled at lower colour temperatures and with shielding over the lights.

Example: LED by Vision’s Stratus LED streetlighting:

  • Available in 35W, 65W, 100W, 135W, 165W, 200W and 230W.
  • Full fitting street light heads.
  • Save 29376kWh. (Based on 120W fitting.)
  • Save 95% on maintenance.
  • 50000 hours lifespan.
  • Three colour options.
  • Instant on.
  • Flicker free.
  • Zero UV emissions.
  • Install heights from 3m to 20m+.
  • Equipped with Philips (Lumileds) chips – Delivers close to 120 lumens/W.
  • Optional photocell/ability to work with solar PV, Photo Voltaic, technology.
  • Meanwell power supplies.
  • ECA qualifying.
  • Carbon Trust accredited.
  • 5-year guarantee.

For more information and to discuss specific high-performance LED streetlighting needs, please talk to an expert today.

Source: CNN/The Conversation.

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