dimmers on bulbs ...

I was told by a lighting designer that a light dimmer can save a lot
of energy.
In fact his claim was that dimming an Incandescent light bulb by 5%,
can save up to 40% of the electricity
consumption.

I tried to verify this claim but I could not find anything that
matched even near this claim.
In fact, what I read (and makes absolute sense to me) is that dimming
the light, say by 50%,
will only save 40% of the electricity consumption.

Does anyone know (and can justify) what the truth is?
I have some basic EE knowledge and I just cant figure out how the
dimming of 5% can give more
than 2-3% savings, given the loss in heat etc...

Many thanks
A

.

Quantcast