gavintc said:
We are the same, where we have been able, we have changed the bulbs to low energy bulbs. Apparently, dimmable low energy bulbs are on the way. If this happens, I can then replace the few remaining in our living room and bedroom.
I also believe that leaving bulbs / flu tubes on is an urban myth. I remember reading it an article, can't remember where that claimed this may have been true in the 60's but is certainly not true with modern flu tubes and bulbs.
I did some work on this a few years ago; on start up there is a small energy boast needed but, only about what the bulb burns in 2 or 3 seconds. So if you are going to leave the room for longer than that it’s worth turning them off.
However, there was a reason for leaving early tubes on, my understanding is that the story that they use less energy left on rather than starting was originally put around by the manufacturers of the long fluorescent tubes when they first came out. In the end of each tube is a little heater that warms the electrode at the ends of the tubes and allows the arc to draw along the tube and hence produces UV light which is then converted into visible by the fluorescent coating on the inside of the tube.
In early tube these heaters were not very well constructed and the thermal shock of warming shorted the life of the heater and hence caused the tube to fail giving the tube a bad name. Leaving them on meant that the tube heaters remained at a constant temperature and hence the life expectancy of the heater was long and the tube life expectancy of the tubes was improved. Now days the heaters are robustly constructed and this no longer applies but has developed as an urban myth.
Long dimmable fluorescent tubes are available as the control circuit has 2 sections; a constant voltage to the heaters to maintain a constant temperature, a variable voltage across the tube to vary strength of the arc and hence light output. In practice the tubes will turn down to a certain point and then go out completely, when the arc fails. Then there is a minimum setting at which the arc will re-strike and the light comes back on. Difficult to see how the small low energy bulbs could be made dimmable without 2 circuits but I haven’t worked in this field of about 4 years so things have probably come on since I last dealt with them.
