In the Dark .... again

28-10-2009

There are times when its like living in a parallel universe, where everyone seems to see the world in a completely different way. Like - for example - a news report from yesterday's newspaper telling me that the town of Toulouse is undertaking a lighting trial that's designed to save them 50% in energy costs. Meaty stuff - so how do they do it?

First you dim your streetlighting by 50%. That's good for me; I live in sight of Poundbury and that's the kind of difference I can take. And then you fit your streetlights with heat sensors so that, as someone passes by, the lights increase to full brightness and then dim down again ten seconds later. Yeah - OK. When do we put on the tin-foil hats?

How sensitive are these heat sensors - and let's assume its a chilly night in Aberdeen and we're all nicely mufffled up - the likelehood is that they'll only trigger as we pass by. And stick with me on this one, but we generally stroll about at around 3mph. So a mile takes 20 minutes, and that means that we can cover about 13m in 10 seconds, or less than the distance between streetlamps. So it all sounds great. The light comes on as we pass by it and it dims down again before we reach the next lamp-post. Is that what they're saying?

But here's another thing. I'd like to invite you to try a little experiment for me. When you're walking along the street tonight, on your way to the pie shop - what do you see? What are you actually looking at? If you're looking at your feet, or the pavement about 2m in front of you in case there's a dog to fall over, then I'll accept the broad argument that this kind of presence detection works. But if you're actually scanning the street about 30m away, looking for muggers, friends you want to avoid, or that nice young lady from the newsagents who's trying to avoid you, then I would maintain that the logic behind this kind of energy-saving initiative is TOSH.

We don't need illumination around our feet - we need it a long way down the street, which is where the trouble usually comes from. Gimmicks, and badly thought-out ones at that. C'est tout.