🚀 go-pugleaf

>Halogens can be more efficient than ordinary filament lamps
>because they run MUCH hotter, so you can get more lumens/watt.

Yes, but also remember that when you run an incandescant lamp with a
dimmer, you reduce the electric bill but also reduce the efficiency.
When you dim your new 500 watt halogen lamp down to give you the
reading light that might equal that of a direct-illumination 100 watt
bulb, you're probably still using about 300 watts of power.

By the way, I got the impression that the longer life-cycle of the
halogen bulbs depends on the recycling pyrolysis of the tungsten
halide lost from the filament.  If that depends on the unusually high
temperature of those bulbs, then one should fear that dimmer operation
might reduce their life -- which is serious because they cost more
than incandescents, because of the quartz envelope, etc.