Halogen lights are around 30% more efficient than normal bulbs, but nowhere near as energy efficient as compact fluorescent light bulbs.

This is especially true when they are grouped together in the form of spot lights in your kitchen for instance. The advantage though is that they give a natural, bright light which is ideal for areas where you need a fairly strong light.
Halogens work in a similar way to normal incandescent lamps but with a couple of drastic improvements. Instead of glass, crystal is used to enclose the filament - which means it can be a lot closer to the heated metal without melting.  As well as this, the bulb contains halogen gas and a filament made from tungsten metal. The filament gets so hot that the tungsten evaporates. It is then deposited back on the wire filament at its thinnest points, meaning a much greater lifespan. This in turn means they reduce your carbon footprint too.

This evaporated tungsten is then deposited back on the wire at its thinnest points, meaning a much greater life span. This in turn means they can reduce your carbon footprint too.

Halogen lights – longer lasting
So halogen lights last around twice as long as conventional light bulbs. Xenon filled lamps can be even longer lasting upto 8 times longer than a conventional lamp. Their construction also means you can expect them to be 30% brighter than normal bulbs.