Regular Light Bulbs vs. LEDs

Did you know that regular (old-style, incandescent) light bulbs have an electricity-to-light conversion efficiency of only about 2%? Yes, two percent. This means that in a 100 watt light bulb, only 2 watts is actually converted into light. The rest is lost as heat. So when you are using a regular light bulb, what you’re operating is essentially an electric heater that just happens to give off a little bit of light, almost by accident, if you will.

Sounds wasteful? Yes, it’s extremely wasteful. We usually don’t keep devices that have an efficiency this low. It’s not technologically or economically feasible. However, most households all over the world still use these not-really-feasible devices.

Had I written this post 15 years ago, we’d just shrug and move on. As it turns out, converting electrical energy to light energy isn’t easy. The most efficient such device available for regular light (as opposed to lasers) is the light-emitting diode (LED) (Edit: For public illumination purposes such as street lights, sodium-vapour lamps are comparable and may be superiour – however, this advantage is diminishing as LED efficiency continues to rise). But 15 to 20 years ago, the commercially available LEDs could only produce coloured (as opposed to white) light and weren’t powerful enough for lighting up rooms. They were (as they still are today) mostly used as indicators (such as power-on lights), signal lights, or for displays.

Fortunately, this has changed. LED technology has advanced greatly. We have white LEDs (which are actually blue LEDs combined with a material, a phosphor, that absorbs the blue light and gives it off as white light) up to powers of many tens and even hundreds of watts, their efficiencies reaching up to 40 percent (in current research) or somewhere between 15 and 25 percent (in consumer products). That is, LEDs are still comparatively wasteful, but about ten times better than regular light bulbs. Doesn’t sound like much? A 10-fold increase in efficiency is huge. In most fields of technology, such an optimisation is unheard of. Imagine your car’s engine being able to produce 1000 horsepowers instead of 100, from the same amount of fuel.

Sure, more efficient lighting products have been around for longer. We have had compact fluorescent lamps (the so-called »energy-saving bulbs«) for decades. Although they have energy efficiencies comparable to LED light (and, as LEDs, are much more long-lasting), there are a number of issues. Their main problem is the ecological impact. Energy-saving bulbs are manufactured using toxic heavy metals such as mercury, where the issue at hand is not so much the toxicity of the small amount of mercury contained in the bulb (you will practically never get into contact with it) but the waste produced both on extracting the mercury from the earth as well as dealing with it when the bulbs are discarded. Also, they require a bit of electronics to drive them (hidden in the enclosure) which requires many materials for its manufacture that are ecologically questionable in large-scale industrial production. (The ecological problems associated with energy-saving bulbs only become apparent at the very large quantities in which they are mass-produced.)

Large-scale manufacture of LED bulbs is certainly not devoid of ecological issues, but much less problematic in this respect. Also, a single, low- to mid-power LED is tiny; much smaller than a regular bulb of the same light output. (Energy-saving bulbs are out of the race here, as they are much more bulky and need many more parts.) Smaller size means less packaging, less mass-transport volume, and so less use of energy for global distribution.

At the moment, we cannot make much use of the space advantage of LEDs. For one, LED bulbs still have to fit into the bulky sockets designed for the old bulbs that have been around since the early 20th century. Also, LEDs need small voltages (in the range of 1.5 to 3 volts), so consumer LED lamps would need special power supplies (electronics, meaning additional parts) so that they can be connected to the 100 to 250 volts of AC power provided in modern homes. Usually, they are designed in such a way as to make a dedicated power supply unnecessary, by cleverly combining a number of individual LEDs, arranged in an enclosure that is about the same size as our old bulbs. Edit: This is incorrect. Household LED lamps for standard lamp sockets do contain power supply electronics.

An often-heard complaint about LEDs as well as the now-out-of-date energy-saving bulbs is the colour, or warmth, of the light that they produce. This used to be more of a problem than it is today. You can buy LED bulbs in a variety of colour temperatures, ranging from yellowish (warm) over neutral to bluish (cold). I actually prefer the neutrally white light over the yellowish light that old-style bulbs produce. It’s excellent to work under, and I like the way that it does not distort the hues of the objects it is shined on. A white piece of paper under neutrally-white light remains white, not yellow. I believe our preference for the more yellowish light of old bulbs is mainly an acquired one. If we can get used to light being yellowish, we can get used to it being neutral. The complaints of people disliking the less yellowish light of LED bulbs remind me of those people who simply object to something new because it’s different to what they are used to.

Light bulbs are a very major part of household energy use. If everyone immediately switched to LED bulbs, energy use for lighting would go down by a factor of something between 5 and 10. This is equivalent to one or two (or more?) power stations that we could turn off.

LEDs have a very long life. A decent LED bulb should last a decade, if not longer. Not only does this mean that in the long run, the currently high price of LED bulbs compared to regular bulbs is compensated for in that you won’t need to buy a new one that often, it also means that fewer bulbs need to be manufactured, reducing the overall ecological impact.

Even though energy-saving bulbs have become much better in this regard over the last 10 years, there is still a small delay between turning them on and getting full brightness. This has to do with their operating principle, which entails heating a component of the lamp until it has fully »ignited«. With LED bulbs, there is no such delay. As with regular bulbs, as soon as you turn them on, they shine at full brightness.

I think there are so many reasons for switching to LED bulbs that replacing your old bulbs (once they fail) with LED ones is pretty much obligatory. Or, to put it another way, you’d be an ignorant fool not to. You’ll be one of the people who got left behind.

With very few exceptions, we’ve replaced all light bulbs in our flat with LED bulbs when we moved here about 1.5 years ago. It’s been an investment of about 200 Euros, but we’ve already benefited from the reduced energy use: our first (yearly) electricity bill was surprisingly low. And the LED bulbs will see quite a few electricity bills before they fail.

Forget about Earth Hour and other such actionist nonsense that calms your bad conscience but helps no-one. If you truly care about the environment and want to help save energy, then replace all your bulbs with LEDs. Apart from simply turning off any devices whenever you don’t need them, it’s the most sensible and real-world effective thing you can do today.

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Author: schoschie

I like to see the wiring under the board™

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