There are several types of light bulbs available, with varying characteristics – especially when it comes to energy efficiency and how much electricity they use. Read on for a quick review of the most common light bulb types available for home use and find out which are best for conserving energy.
Incandescent light bulbs
- established energy wasters
Incandescent light bulbs are what comes to most people’s mind when they picture a light bulb. This is no surprise; it is by far the most widespread lighting technology for home use.
The incandescent light bulbs has been catching a lot of flak for a number of years now, and quite rightly so, many would say. While they’re quite cheap to buy, they’re also horribly inefficient at their actual purpose: producing light. The majority of the electricity these bulbs use are converted to heat, rather than light.
The light and heat they produce are generated by an electrical current flowing through a tungsten filament inside the bulb. The current heats the filament until it glows. A gas mixture contained by the glass keeps the filament from overheating. Over time, this gas mixture leaks slowly out of the bulb, eventually allowing the filament to overheat and burn out. This is what produces a bright flash of light and an audible pop when the light bulb goes out.
A regular incandescent light bulb will produce about 13 lumens (a measure of the perceived power of light) per watt. Another form of incandescent bulbs – halogen lamps – rate slightly better: they give out about 17 lumens per watt. In both cases, though: Not very energy efficient.
The typical lifespan of an incandescent light bulb is around 1000 hours.
Fluorescent tubes
Fluorescent tubes aren’t actually light bulbs, of course (well, duh). They’re a common enough light source that they deserve a mention, though.
Fluorescent tubes large and unwieldy, compared to any of the other light bulb types. This, along with their reputation for producing cold and unflattering light, has traditionally confined their use to schools, offices and other workplaces. While tubes that produce a warmer and softer light are increasingly available, their size issues still remain.
A fluorescent tube is a long tube of glass with electrodes at each end. The tube is filled with argon and coated on the inside with phosphor. When electricity moves through the gas from one electrode to the other, ultra violet radiation is emitted. This radiation is then absorbed by the phosphor coating and then re-emitted to the outside of the tube as visible light.
Typical fluorescent tubes will give around 65 lumens per watt – quite good energy efficiency. They’ll also last considerably longer than an incandescent bulb. If tubes in a particular lamp seem to wear out often, it might be time to replace the control gear, as an old control gear will make tubes wear out quicker. The control gear usually looks like a small, white cylinder and is located near the tube it controls.
The life span for fluorescent tubes is usually between 10000 and 20000 hours – considerably better than a typical incandescent.
Compact fluorescent lamps (CFLs)
CFL light bulbs are basically thin fluorescent tubes that have been coiled to take up less space, with their control gear placed in the socket. They are nearly as small and feature the same sockets as the traditional incandescent bulbs. This makes them a lot more versatile than regular fluorescent tubes.
Older CFLs need a little time to warm up before they reach their maximum output of light. This means they might give out a somewhat gloomy light for the first few seconds. Avoid using them places where you need full light output directly after switching the light on.
A typical CFL has good energy efficiency. A 15W CFL will give out about the same amount as a 60W incandescent bulb, providing up to around 60 lumens per watt – not too shabby. The life span for CFLs vary quite significantly, with product quality affecting it greatly. A few makes have a life span as low as 1200 hours, most will last around 10000 hours, the best will last up to 20000 hours.
Light emitting diode lamps (LED lamps)
LED light bulbs and lamps are often touted as the future of efficient and energy saving lighting.
LED technology has been around for quite some time. You’ve certainly seen LEDs; they’re the tiny colored lights used to indicate things (on/off etc) on TVs, amplifiers and other appliances. Relatively recently, white versions of these have become economically viable for use in general lighting applications.
The LED is a simple semiconductor that glows when electricity flows through it. The LED itself is usually quite small – less than one square millimeter – but it comes with integrated optical components (a fancy way of saying ‘a blob of glass or plastic’) to distribute and direct the light.
Individual LEDs are too small to provide useful lighting – bulbs and other LED based light sources are usually clusters of several LEDs in a suitable housing.
LEDs by themselves have the potential to run at a very high efficiency – up to 160 lumens per watt. In practice, though, this is impossible to achieve for regular household lighting. LEDs need low voltages to operate, much lower than what home sockets provide. To get the voltage down to acceptable levels, LED light sources need control circuitry, which brings the efficiency down. In practice, current typical LED bulbs provide about 40-60 lumen per watt.
The real advantage of LED lighting, though, is long lifetime. For low quality lamps, it starts at 30000 hours, with higher quality lamps going as high as 50000-60000 hours. A LED lamp has no filament that might overheat and no gas to leak out – and consequently lasts longer.
Amazon has a decent, and growing, selection of LED lamps. Choose your preferred Amazon site here:
Recycle them all!
Regrettably, all the light bulbs and tubes above must be considered hazardous waste. They all contain substances that really shouldn’t be let freely into nature in any significant quantity.
My next post on lighting will provide more info on this, but in the meantime: ensure that any light bulb – including the old incandescents – ends up at a proper recycling center. Don’t toss them in the bin along with regular garbage.
[Update: My post on recycling has now been published: Light bulbs are hazardous waste]
This post was tagged with: CFLs, fluorescent tubes, incandescents, LED lamps, LED light bulbs, light bulbs, lighting, types of light bulbs