They are now using LEDs but with technology that has not been time or endurance tested.LED's use a small amount of current, but they are expensive, and are only cost effective over a very long period of time.The problem is that whilst LEDs do have a very long life they lose up to 60% of their luminance effectiveness over a comparatively shorter period.Simply, they get dimmer as they get older.You might have noticed this on the rather simple LEDs that illuminate bus stop signs, that are now several years old and almost useless.This problem with LEDs has not been technically solved yet. So compared with a current High Pressure sodium unit which is very cheap, the energy savings are greater, but this is cancelled out by the higher cost of the LED unit and it's short 'effective' life which is vastly different to the manufacturers claimed 'actual' life. Two different things.It's the same distortion of fact with domestic low energy light bulbs.True, they last and use low wattage, but they use a huge amount of electricity to actually illuminate. If you have one in say, the loo, each time you switch it on, you use the same amount of electricity as you would if you left an incandescent tungsten bulb on for an hour. So, if you use the loo as families do frequently, you are actually using far more electricity than with the old type bulb.This is caused by the requirement for the low energy bulb to have a large charge burst of electricity to illuminate it, using an inbuilt capacitor.It is therefore is actually cheaper to leave the low energy unit on for 5 hours than it is to switch it on and off 5 times over the same period.Not that they ever bothered to tell anyone that as they would never have sold.!
Anthony Waller ● 4397d