Comparing light bulbs: upfront costs vs running costs

Do you know the difference in annual energy costs of an LED (light emitting diode) lightbulb and a halogen bulb? You probably know that halogens are cheaper to buy, and more expensive to run, but do you know how great that difference is?
I didn't, until I visited the SHEERLED stand at Ecobuild this year. What would you guess? Twice as much? Five times? Ten times more expensive? Well double it. Yes, the cost of lighting your house with halogens is twenty times as much per year as the cost of lighting it with LEDs.
The difference is not as great with CFLs (compact fluorescent lamps) but it is still four and a half times cheaper.
There are three elements to take into account when you do these calculations. The upfront cost of the bulb; the cost of the electricity used to run it; and the life of the bulb. Incandescent and halogen lamps are much the cheapest to buy, but they fall down on everything else.
TP24 did its calculations based on a typical modern kitchen which would have 5 halogen lights. It compared the costs of these with the equivalent CFLs and LEDs. Its figures are based on the lights being on for 8 hours a day, 7 days a week for a year. I suspect that most of us don't have them on that much, but if you do the figures may prompt you to turn them off more!
The annual amount added to your electricity bill for running those five lamps would be £95.37 for halogen, £20.98 for CFL and £4.77 for LED. Add to that the fact that LEDs last for 20,000 hours, CFLs for 10,000 hours and halogens for just 1,000 hours and changing them rises speedily up the priority list.
The upfront costs for LEDs and CFLs are more: £9.95 for 5 halogen lamps; £24.96 for CFL and £34.92 for LED. But even at these prices, you're saving money six months after you've bought them. Click on the table above to enlarge it and see all the figures.
LEDs are increasing in performance at an incredible rate. Two years ago you could get 25-30 lumens per watt. Now they are generating between 65 and 100 lumens per watt. You may want to test one bulb to make sure you're happy with the light it gives before investing in large quantities. You can buy lamps that plug straight into the halogen fittings.
The one complication is if you have your existing halogens or incandescent bulbs on a dimmer switch. You can get dimmable LEDs, but they cost much more (between £20 and £45 each compared with £7 to £9 for standard LEDs). Alternatively you could get an electrician to change the switch to a simple on/off one.