Best light bulb?
Changes to how lamp ratings are described:
For as long as most will remember, the ‘brightness’ of a light bulb (or lamp as we prefer to call it) has been measured in terms of how much power it uses (in watts), rather than by how much light it produces (in lumens). But, as a result of EU legislation, this approach has been slowly changing, affecting the information manufacturers display on the packaging of their lamps.
Historically, we selected the traditional household incandescent ‘filament’ lamp on the basis of how much power it used. For example, regardless of who made the lamp, most knew that one with a 100 W rating was the brightest for normal domestic situations indoors and, for something less intense such as mood lighting, a lower rating of 40 W or even 25 W was preferred.
However, the energy needed to power the newer types of energy efficient lamp, such as compact fluorescent lamps (CFLs), light emitting diodes (LEDs) and halogen lamps, no longer indicates the amount of light they produce. For instance, the light output of an 8 W LED is comparable to that of a 9 W CFL, but they both produce more light (lumens) than a 28 W halogen lamp. So, to be certain that a new or replacement lamp will provide the expected level of illumination, it is now necessary to select it on the basis of its lumen output, not its rated power in watts.
The greater the lumen output, the ‘brighter’ the lamp. Of course to find the best light bulb, other lamp characteristics such rated voltage, size, base and colour temperature will still need to be taken into account. Some manufacturers have been displaying the lumen output on their products for some time now. They have used a number of ways to indicate the equivalent value in watts.
For example, phrases such as ‘replaces 60 W bulb’ and ‘this 13 W energy saving lamp is equivalent to a 60W lamp’ are common, but this practice is expected to be phased out as consumers become more familiar with the lumen rating concept. The Lighting Industry Association has produced a free chart to aid the selection of energy saving lamps in relation to the former ‘watts’ rating method.