Purchase and running cost graph

Running costs

Running costs depend on the efficiency (efficacy) of the lamp. It's measured in lumens per watt (lm/W) which is the light output in lumens per watt of electricity used. The higher the number, the more light produced for the electricity used.

The LED replacements for standard light bulbs showed substantial savings. They were 5 times more efficient than standard incandescent bulbs. That means a standard incandescent bulb costs 5 times as much to run as its LED replacement.

The savings weren't as dramatic for downlights and spotlights but they’re still worth it. LED downlights and spotlights are 3 to 4 times more efficient than standard halogen bulbs. So a standard halogen downlight costs between 3 and 4 times as much to run as its LED replacement.

Outdoor security PAR lamps had similar savings to downlights and spotlights.

+ purchase costs

These figures really matter: there's not much point in going for low running costs if the bulb costs a fortune to buy (or vice versa). We calculated the costs of different types of bulbs over a 5-year period.

Incandescent bulbs cost less than a dollar to buy – but they eat electricity and only last a year or so. So over 5 years this makes them an expensive option. Their high electricity consumption also wastes energy resources.

LEDs have low running costs, although can be expensive to buy. The testing shows paying more doesn't necessarily mean a better product. Because the purchase cost of the LED bulbs varies hugely, their cost over 5 years also varies hugely. We think the 5-year overall cost becomes unattractive when the LED bulb is priced at more than $40. It seems certain LED prices will reduce over the next few years and that will make them more cost-effective.

CFLs also have low running costs and they're not too expensive at about $8 for a 20W bulb. That makes the cost over 5 years very attractive. LED bulbs should outlast CFLs, but we think the lower purchase costs of CFLs makes them more cost-effective for now. Also LED bulbs have yet to produce the light output of a 100W incandescent (or 20W CFL) bulb.

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