The two most basic specifications average and knowledgeable consumers look for in lighting is how many lumens that light produces, and how much wattage it requires to work.
Although lumens and wattage are fairly simple terms to define and grasp, a step further can be taken to fully understand how lumens and watts relate to light quality and efficiency.
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When it comes to lighting lumens are most people’s number one priority, but many confuse lumens with watts. A lumen is a measurement of how much visible light a bulb produces. More lumens mean a brighter light, fewer lumens will mean a dimmer light.
Depending on where and why the light will be used, lumen requirements will vary to get the desired level of brightness. It’s not uncommon for people to choose a 60-watt bulb over a 50-watt bulb thinking the 60-watt will provide brighter light – which is an incorrect link of power consumption to light output.
It is important to note that for non-directional bulbs that emit light in all directions, the total lumens of a light include the lumens lost as “spilled light,” or light that is not directed at the intended location and deemed generally “not useful”. Some manufacturers will include a “useful” lumens rating which measures the total light emitted in a standardized 90-degree cone.
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As mentioned above, the function of lumens and watts is sometimes confused. Lumens measure the amount of light output, while watts are a measure of the amount of energy required to power a light.
A 60-watt lightbulb will consume energy at a rate of 60 watts per hour, expressed as 60kWh, or 60 watt-hours and 0.06 kilowatt-hours on a utility bill.
Going back to the 50-watt or 60-watt example, we can see how buying a 60-watt bulb does not mean it will be brighter, but that it will require more energy to be powered. The less watts a light consumes, the more energy efficient that light is.
This is why LEDs have been such a sought-after technology. LEDs are very energy efficient, requiring lower wattages than traditional bulbs, while producing the same amount or more lumens.
For example, an 8-12 watt LED bulb will provide a similar light output to a 60W incandescent bulb. That’s a huge amount of energy savings for the same number of lumens.
Now that the difference and functionality of lumens and watts is clear, it’s easy to see how both measurements are key to buying lights that provide the best light output and energy savings possible.