First, let's set some context. As you may or may not be aware, traditional incandescent light bulbs are being globally phased out and typically replaced with low energy light bulbs.
At present the low energy lighting market is still dominated by CFLs (Compact Fluorescent Lamps) which, compared to incadescent lamps, are about 4 times more efficient (or put another way, waste only 25 percent as much heat).
However, CFLs are universally unloved by consumers, manufacturers and environmentalists. They are a poor product aesthetically (which is a bit of a killer for lighting), are awkward to dispose of unfortunately due to their mercury content, and complex to make.
They also compare unfavorably against LED lighting on all these counts and a few more such such as: they do not deliver full brightness immediately; tend to be bulky; are poor for spotlight applications; and do not actually last all that long and certainly not remotely close to the 40,000+ hours for an LED.
But the major factor is that LEDs are already 10 times more efficient than incandescents, rather than a mere 4 times, and also doubling this performance gap every 18 months or so.
So should you be buying LED light bulbs instead? Well that depends; principleally on what exactly it is you plan on buying. Cheap, low power LEDs are frankly not up to replacing most existing lighting and for the most part a false economy. But the more expensive brand name products most certainly are a sound investment and the cost savings can be quite remarkable.
Now you've probably gotten used to assessing light levels according to wattage ie 100w is very bright, 40-60w comfortable, below 25w gettingather dim. LEDs do not conform to this scale.
At present you can estimate that an LED will consume slightly above one tenth the power to deliver the same amount of light, so 6w should be adequate to replace a typical 50W halogen spot lamp for example.
Obviously, as LED performance improvements, the required wattage should also drop accordingly, so you may find that soon a 4W LED can replace a 50W incandescent lamp, but we're not there just yet.
A better way (than wattage) of assessing brightness is luminosity, measured in lumens. For examplem a regular 40w bulbs deliveries about 360 lumens. However, luminosity alone is not sufficient to gauge how bright a light source actually appears. Beam angle and light "color" are also crucial.
LEDs are intrinsically directional and thus have a fairly narrow beam; they have also in the past tended to be on the cool side of things, which we perceive as bluish. This produces quite a harsh effect with small areas of very intense light in a sea of dark spots. Good quality LED spotlights will advertise their beam angle (120 degrees is plenty wide enough and will create a good, uniform light pool).
There is also the matter of light color, measured in Kelvins. Anything below 3000k is classed as "warm white" and values above 4000k are termed "cool white". For most domestic situations yourought to be looking at around 2800K to recreate a familiar atmosphere.
So in summary, to determine whether LED light bulbs will do the job you personally want, check the packaging (or description if buying online or from a catalog) for:
- manufacturer's name
- price and warranty (good LEDs are cheap to run, but expensive to buy)
- luminosity
- beam angle
- light color temperature
- average life time (aim for 40,000+ hours)