Then a year or so later, the tubes were replaced with longer lasting and much more energy efficient tubes. They can be identified by a green ring at the end of tube. I was not so happy about them all being replaced at once and presumably the old ones thrown out. They should have been progressively replaced as they failed. I wonder if the same will happen with these.
Ok, I've looked at some information and two 36 watt tubes are replaced with one 19 watt tube. When movement is undetected, the wattage drops to 6 watts and still provides security lighting. Oh dear, these seem to cost upwards of $250 each. That surely can't be correct.
Here is a photo of the two types of LEDs that I think are under consideration and this link has some further information.