How To Slash Your Energy Bills With LED Lights
You’re probably expecting the usual fluffy “how to” article – the sort that opens with a few insipid generalisations before meandering into a less than thunderously convincing argument vaguely related to the title. If so, prepare to be disappointed/pleasantly surprised (delete as appropriate); I have neither the time nor inclination and frankly the data speaks for itself. So let’s pitch in and start doing some math.
The average mains powered GU10 halogen down light (as very commonly seen fitted into ceilings) can be bought for around 2, uses 50 watts of electrical power and has a lifespan of about 2,000 hours over which time it will have cost 12 in electricity to operate. This is based on the average price of 0.12 per kWh and having the light on for a mere 3 hours a day (which works out at close to 1,000 hours over the course of a year).
A GU10 LED replacement (i.e. an LED with near identical performance characteristics, such as the Sharp Zenigata) consumes 4 watts, costs at present 24 to buy, has an effective lifespan of over 40,000 hours and will cost 0.96 to run over the same time period.
Looks like the LED has priced itself out due to the much higher purchase cost, doesn’t it? But let’s add a bit more “real world” perspective into this picture.
For a start, the longevity of the LED is such that the halogen lamp will need to be replaced 20 times – that’s 20 x 2 which means that the purchase costs (plural) for the halogen are in fact 40 against 24 for the LED.
Secondly, if we run our comparison using the life span of the LED instead of the woefully short-lived halogen we see that where the LED uses just 19.20 worth of electricity, the halogen burns its way through 240.
Finally, let’s add back in the “real” purchase price differential and over 40,000 hours it looks like using halogen lighting costs us 280 whereas the equivalent LED instead costs 43.20. We’re way beyond projected savings of 10%, 20% or even 50% – the running costs of halogen lighting are over 1000% more than comparable LED lighting.
Even when the purchases prices are accounted for, halogen lighting is still over 700% more costly. Halogen lamps appear cheap because each costs relatively little to buy, but the truth is they actually end up costing twice as much as an LED because of the frequent replacements, and they are massively more costly to run. LED’s are a completely different ball game and interestingly sometimes cost more to buy than to operate (as this example illustrates).
Needless to say, this illustration is somewhat low-scale and examines just one very lightly used light bulb. However, I noticed en-route from my North facing (hence gloomy) kitchen that 10 down lights stay on in there from early till late, then passing through the hall I spotted 4 more and here in my office 6 more are switched on for a good 6 hours daily.
Totting this lot up we can see that even these 3 rooms use more than 100,000 hours worth of electricity each year (that’s ((6*6hrs)+(10*17hrs)+(4*17hrs))*365 days = 100,010 hours) which works out at (100,000 * 50W * (0.12/1000)) 600 just in electricity costs for halogen lighting, compared to a rather more reasonable 48 for LED lighting.
If we look at real life examples such as shops, offices, hospitals, hotels, airports and so on, where it is commonplace to use artificial light almost all the time then things get really interesting. Economics is little more than mathematics with currency symbols, and if we extrapolate our simple calculations above the numbers start to resemble seriously big bucks.
We have demonstrated that, despite initial appearances, the purchase price of an LED is about half that of an equivalent halogen lamp when you account for the repeat-purchases as it wears out. We have also calculated that overall electric lighting using halogen lamps is 12 times more costly than replacing them with LEDs. So the one question remaining then is this: why would anyone stick with halogen lamps?
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