Dave Plowman wrote:

You're the only one who has put a figure on it. Since
so many on here are very keen on any sort of energy saving lights, I
thought they'd all have some figures to hand.

Since you exclude the cost of the actual LEDs, don't tell us how many
hours/year they are lit, how many rooms are occupied for how long, etc,
the easy answer is to say they'd save at least 85% of what the spend on
powering the tungsten lamps ... assuming no change in behaviour.