Wildwood, for the life of me, I can't see that because a 20W energy efficient bulb is supposed to be five times more efficient than an incandescent bulb, it can be said that the incandescent equivalent is 100W.
I'm not questioning the arithmetic which is obviously correct, but I can't see a correlation between efficiency and equivalent wattage. The point is that a substantial amount of wattage consumed by a incandescent bulb are lost as heat. I can't see that such figures could be calculated without taking this heat loss into account.
What exactly is "efficiency" as used in this context?
I went out today and bought two 20W Philips Energy Saver Bulbs. The packaging states that each provides the equivalent of a 100W incandescent bulb. I tried them out in a closed room with no windows, left them on for 25 minutes and judged the total light output. I then replaced them with two standard pearl 100W incandescent bulbs. I'd say the energy bulbs provided about 60% of the light of the incandescent bulbs. You say I should have had about 120W of light equivalent from the energy bulbs; the packaging says I should have had 200W of light equivalent from the bulbs.
Are we now at the point where we are expected to guess how many of these bulbs are equivalent to incandescent lamps? Perhaps we are expected to put in extra light fittings just in case we need more bulbs. There certainly doesn't seem to be any consistency in these equivalent ratings and to my mind, there should be.