But the cost of running one 500w halogen, soon builds up. The lights around my house are on Light sensors/timers. So they could be on for 12hours a day for 8months of the year and 6 hours for the rest.
Over a yr, the difference between 500w and a 20wCFL or LED is massive
I'd actually suggest running 2 different fittings at they have 2 different jobs to do. Go for a halogen for the key fumbling and set it on a short timer. Then for BBQ's etc I'd fit a 70W asymmetric metal halide. It gives a much nicer quality of light with a better distribution pattern, that is more suitable to events.
Can do but a decent power led is brighter, lower maintenance cost, much lower power cost and instant starting. Have fitted loads of very how power units at work and while there £500 a pop the pay back time in electrical saving is around 2 years but that's with them on dawn dusk. It's now like day light when walking around the building and the sheep are very confused!