The first thing that seems to spring to mind when you mention carbon is changing your lightbulbs. That's good because it's easy and, once you've done it, it takes no further effort.
A lot of people though, including Tesco's Sir Terry Leahy, have pointed out that we can't just BAN high-energy lights because they are not suited to all situations, a lot of current light fittings won't use them, etc. How far is that true?
Energy-efficient bulbs for the standard bayonet (BC) or screw (ES) fitting are now sold for under a pound in supermarkets, department stores and the like. They are longer than their equivalent high-energy bulbs, however, so they might not fit your existing lampshade or luminaire. In that case, you need to get hold of the tiny little energy-saving bulbs that are now available from online retailers - I've listed some below - for even the small bayonet (SBC) and screw (SES) fittings. They work really well. Yesterday, I replaced a 40 watt tungsten "golfball" bulb, 95mm-long, with an energy-saving equivalent that is 5mm shorter and 35 watts lighter.
Unfortunately, these non-standard energy-saving bulbs cost £4 - £8 each which is a big barrier to replacing all the tungsten bulbs in your home.
Halogen downlighters and spots are the very epitome of modern lighting. Bright and affordable, they claim higher efficiency than regular tungsten filament bulbs. In practice, they are highly directional so that many more bulbs are needed to light a room than with traditional bulbs.
Just before I started to think about energy efficiency, I fitted 12 mains-powered halogen bulbs in a long, narrow utility room at home. I think this stupid deployment of 600 watts was the first thing that made me feel guilty about my household energy consumption. Fortunately, I discovered Megamann 7 watt compact fluorescent spots and spent a hundred quid reducing this figure to 84 watts.
Sad to say, these are only available for 240v lights so I don't think we can do anything practical yet to replace all those 12 volt halogens our homes are filled with.
I have just tried out some 1 watt LED replacements for the little 10 watt halogen bulbs with two metal legs coming out of them (called G4 capsules). They were £5 a piece, very fragile (I broke two), difficult to fit and produced negligible illumination with a ghastly mains flicker.
Furthermore, the power consumption of the transformer supplying 12 volt DC to the 1 watt LED was still 15 watts, so the real saving was 50% rather than the 90% I had hoped for.
My next stop was the lounge and dining room, with a grand total of 17 matching wall and floor lights, each using 40 watts. The Omicron replacements, at 5 watts each, have cost me £140 but they are saving 600 watts between them.
My latest discovery is energy-saving striplights, to replace those long filament bulbs built into bathroom mirrors, furniture and under kitchen cabinets. The 221mm bulb uses 5 watts rather than the 30 watt incandescent bulb: the 284mm one uses 7 watts in place of 60 watts.
How about Tesco start piling them high and selling them cheap so that we can all switch more of our lights over to energy-efficient bulbs?
In the meantime, please check out these online retailers and buy all the energy-saving bulbs you need, and can afford, to replace your high-energy incandescent lamps. I have been happiest with BLT Direct because their prices are fair, they deliver quickly and they handle returns very efficiently.