Saturday, October 13, 2012

Light up the night

Cities like Glasgow use blue LED streetlights for aesthetics
photo Gregor Sands

You probably don't even know. But nowadays it is impossible to ignore his invention. In 1963 Holonyak invented the Light Emitting Diode (LED). A few years ago Randy Atlas blogged here on LEDs in CPTED. 

Today LEDs are flooding our street scenes. Those eerie, brilliant and glaring LEDs are showing up everywhere from Manilla to Sydney to Las Vegas.

Oakland California, for example, is replacing 241 sodium street lights for LEDs in high crime locations (chosen by police). Cutting crime with LEDs? Do LEDs cut crime any better than other types of street lights. Or at all? What do we actually know? 

We know LED color rendition is excellent and it tends to spread light more evenly. LEDs can create glare in rainy or snowy conditions. Because LEDs give off very little heat, I am told they tend to ice over in ice storms, something heat-generating sodium lights seldom do. 

I can also personally report you'll burn your retinas if you look directly at them (not one of my Einstein moments).

LED glare on the left compared to sodium lighting- photo Chris Dushek
The brighter-is-better crowd loves LEDs. Power authorities are thrilled due to 60% energy savings. LED companies are drooling at booming sales.

Yet, there is a conundrum. On one hand we promote an evidence-based, scientific approach to crime prevention. On the other we adopt LEDs without specific evidence about the effect of LEDs on crime or perceptions of safety. 

The best existing research does show positive effects in some situations for lighting in general. That refers only to lighting quantity, not quality. There is also research showing the reverse. 

It's okay to adopt energy-saving lights. It's delusional to think they'll automatically cut crime. They might. Or they might make things worse.

Blue street lights cast evening hue over Glasgow - photo Jason Hawkes, Daily Mail

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