technology bulbs output different light per watt.  For example, incandescent bulbs may output 18 lumens per watt. Fluorescent may do 70 lumens per watt.  Other technologies such as Halide may do almost 100 lumens per watt. It's incorrect to say the Watt is not a valid unit of measure for light. You can precisely measure and characterize optical power in Watts as a function of wavelength. Don

In other words, those silly 40 watt lightbulbs give little light in comparison with the amount of money it sucks away, and that dimming the lights may be less frugal than switching a lightbulb off. In other words? Yep.

That is where this discussion began.  That is the question raised by the original poster.  A '100 watt equivalent' bulb will not consume 100 watts no matter how Tom Quackenbush tries to put a spin on it.  Without numbers, he only posts junk science reasoning.  I think he is looking for a way out of his original statement rather than admit he was wrong.  His problem - I don't believe in letting junk science reasoning go by without burning feet of the junk scientist.  Promoting junk science is that evil. I'll snip the almost intact quote of my previous post to save space. I did notice that you snipped the simple question that I asked. Here it is for the third time What unit of measure is commonly used for solar insolation Were you unable to find the answer? Or did you find that the answer is watts per square meter (or square feet, etc) and not answer because it contradicts what you said, Watts are not a valid unit of measure for light. I was perfectly willing to explain to you why watts _are_ a valid unit of light and how that does not contradict the use or usefulness of lumens as a unit of measure. I _was_ willing. Now you're resorting to putting words in my mouth and outright lying.  I'm not willing to explain any more. Perhaps you can find someone who _passed_ high school physics to expalin it to you.

They're great for places where the amount of light isn't crucial (outdoor lights, bathroom, kitchen, closets, etc.) but I gave up on using them in my main living areas (living room and bedroom).  It was just too uncomfortable for reading - and I like bright light over the entire room, not just focused on one spot. Like yourself, I also decide _base_d on application. I have at least one CF in every room, so if I'm planning to leave one light on in a room for awhile, like when guests are here and moving around the house, I can use the CF for that purpose. With some overhead lights with two sockets, I'll use an incandescent and a CF together. In that case, nobody is able to tell there's a CF in use, IME. I use a rather dim CF as a bedside reading lamp. I find that it tires my eyes slightly and makes it easier for me to get drowsy and sleep.