You may have heard a lot a talk about lumens recently, but what are they and why do they matter?
In most simple terms, lumens are a measurement of light. More specifically, they are used to measure the total amount of light (or brightness) produced by a single light source. Increasingly, light bulb manufacturers are using lumens on their packaging, to help consumers make more accurate decisions about the type of bulb they need.
Historically, it has been watts that have provided this information, but with bulbs becoming more energy efficient due to the increased adoption of LED technology, wattage is becoming a far less accurate or relevant metric in lighting – modern LED bulbs can produce equal (or more) amounts of light using less power than their traditional equivalents. For example, most would assume that a 6.5W LED bulb would produce less light than a 50W halogen bulb, but because the low energy LED bulb is capable of producing a higher light output while using far less power, this isn’t always the case.
Ultimately, lumens just make more sense, as choosing a light bulb should come down to the light produced, and not the energy consumed in doing so. As a helpful pointer, many modern LED bulbs will be accompanied by an approximate equivalent watt specification on their packaging, but it will likely be some time before lumens are accepted as the ‘go to’ lighting metric amongst consumers.
Lumens Vs. useful lumens
When comparing lightbulbs, it is not enough to look at lumens and watts alone. This is because lumen levels are measured differently between different styles of bulb. For directional bulbs, such as spotlights, some of the light produced may be ‘wasted’, but is still counted in the total lumens rating. But, for non-directional bulbs such as candle, globe, or ball shape, the lumen output is measured in all directions.
In a bid to make light bulb comparisons more straightforward, a new useful lumens rating was introduced which only measures the light that is released in a 90° cone from the centre of the bulb, ignoring any light that is split or ‘wasted’. This measurement is more accurate for spotlights in particular as the light is only emitted in one direction.
How many lumens is enough lumens?
Every room will have its own lighting needs depending on size, ceiling height, colour scheme, the amount of natural light coming into the room, and how the space is used. Therefore, there’s no optimum lumen level, so to speak. However, the below cheat sheet provides a useful introduction into the ideal lumen level for various settings:
To assess a light bulb in terms of its energy efficiency, wattage remains a vital statistic. However, in order to gain a true understanding of how bright a bulb will shine, the answer lies in lumens.