Here I want to share my personal impressions of various public lighting solutions. Took some snap shots to illustrate (photography is not my forte, but hopefully decent enough to give an idea).
I may have mentioned earlier my unpleasant experience of the Häggvik tunnel north of Stockholm, which has been fitted with cool-white LEDs. The light was so harsh and glaring that my first impulse was to keep my eyes shut until I got out, but that’s not so practical when driving…
Edit: Found a video of the installation, with better images of the finished results. http://www.youtube.com/watch?v=z_P2aq-TyBw
These LED lamps have a promised life of 50.000 hours, although economic life is estimated to be shorter by a factor of 0.8 (not exactly sure what that means) which has to be balanced against initial high price while still requiring maintenance every 4 years like other road lamps.
It seems this is one of several experimental installations included in the Swedish Traffic Administration’s project called New Light, aiming to cut road electricity consumption in half by 2016, and funded by the EU-project ESOLi.
Another part of the project includes testing solar powered LED lamps at bus stops in the Kalmar region: http://www.youtube.com/watch?v=aHb_U1xi61w
And rubber-covered luminaires for costal areas, making it too slippery for sea birds to land and poo: http://www.youtube.com/watch?v=miofKbxLM7o
On a more positive note, I was visiting another Stockholm suburb recently where the old HPM street lights had been replaced by a ‘cobrahead’ with warm-white high-power LEDs. Probably one like this. This was much better than the cool-white LEDs in the tunnel! The light colour was a nice and balanced golden-white, not yellow, pinkish or greenish as the cheaper ‘warm-white’ LEDs often are. Not as glaring as the cool-white LEDs (unless you looked right up at it) and bright enough to light up the street well (at least now in the beginning).
My only objection would be a lack of softness, as the light comes straight down in a rather distinct and harsh way, unlike fluorescent and HID light which diffuses more softly to the sides, and incandescent light (including halogen) which also has a nice glow. Astronomers might appreciate this straight down quality, as it probably causes less light pollution. You could also clearly see the rows of individual light dots that made up the construction, which was not so attractive to look at. (I tried to photograph it but that didn’t come out well.)
If LED light last as long as claimed without losing too much output over time, this might be an option at least for highways where stopping traffic to replace lamps is an extremely costly affair. Better color rendition also gives better vision, which helps keep accidents down.
Then I went to Arlanda airport to check out the warm-white LED lamps in Terminal 2. Huge tubular luminaires, specially designed for maximum reflection, combined with large boat shaped skylights to let daylight in.
Here I managed to capture in the glass reflection all the little light dots inside, which in real life are quite visible to the naked eye (if one looks up). But the depth of the barrel-like luminaires gives a good enough shield against glare.
Light colour was quite incandescent-looking. But unfortunately not enough of it to make Terminal 2 as bright as Terminal 4 (lit by fluorescent tubes and skylights) despite there being a great many of these LED clusters.
In fact, without the skylights and the additional lighting from Compact Fluorescent downlights and Metal Halide floodlights, it would have been even more gloomy. The ceiling height probably requires a more potent light source. This ad lit by only two Metal Halide floodlights was the brightest thing in Terminal 2:
Two winters ago I was at a Light Event in Djurgården, Stockholm, arranged by Quist AB, that had around 20 different installations with coloured LED light. Really creative and fun! They have also arranged Light Events in other cities, using coloured LED to illuminate everyday spaces in an exciting new way.
This is how LED light is best used, in my opinion. For decorative purposes, it seems LED light has infinite potential.