The total amount of light that illuminates surface is known as lux. These are described as units of brightness. If a light-emitting device is closer to a surface, the higher the lux will be. This brightness exists on a sliding scale. For example, if you could imagine a dark room and a single light hovering over a table, the light being emitted onto the surface of the table directly beneath the bulb is the brightest, meaning the lux measurements is at its highest. As you move further away from that direct point, the lux measurement also decreases.
By contrast, lumens are a measure of the total amount of light generated from a lamp or other direct light source that is visible to the human eye. Watts measure the energy it takes to power an incandescent light source, whereas lumens tell us the brightness of an LED or Halogen light.
It is incredible how energy efficient today's light bulbs are. This has required us to look at their measurements in a whole new light. The use of energy-efficient light bulbs are encouraged in New Zealand, so it is important to have a means of ensuring that light bulbs have a maximum brightness from minimum energy output.
For example, you can appear to have the same brightness with an old 75W incandescent bulb as you see from a halogen 52W, a compact fluorescent bulb using about 16W or an LED using just 4W. Therefore 1,100 lumens would look equivalent to the of the same 75W incandescent light bulb. But by using this new point of measurement, consumers are now ablate make the right decisions when purchasing new light sources. These energy-efficient light bulbs are measure in lumens per Watt (lm/W) — the higher the better.
The measurement of Lumens is easy to see in household use, but what about lux? While these two measurements of light go hand in hand, lux is the one that can most accurately shed light on the rest of the field.
Lux measurements are vital to several applications. Most notably are places that require very specific measurements of light. One such example is in a modern hospital's operating theatre, where seeing clearly is vital to a doctor's success and patients recovery.
Another would be in the art world. The inability to measure lux would have a disastrous effect on preservation, as even low light levels — when seen over a long period of time — can deteriorate and ruin everything from oil paintings to cloth tapestries. This damage is caused by lights radiant energy, through radiant heating or photochemical action. Furthermore, the duration and intensity of these potential sources of destructive energies exist outside the spectrum of visible light. Important documents and other paper content can also be susceptible to damage by low light levels.
Another example is the illuminance recommended when it comes to maintaining an office setting. Because more than 80% of information is presented visually to most company's staff, the ability to not only maintain adequate light but also provide optimum lighting conditions can make a real difference in employees lives and company efficiency. For example, the minimum lighting for a task like paint retouching or the colour-matching of dyes requires an illuminance measurement of 800 lumens or more. Similarly, watchmaking and its minute mechanisms require 1600 or more lumens.
For the vast majority of people, more time is spent at our workplace than anywhere else. This is why it is so important to have accurate lux measurements to ensure that the entire workforce is set up for success. The luminous flux per unit area between a light source and the area illuminated by it is measured using the lux meter. To measure these readings efficiently and precisely a photometer is also required, such as those from Testo's line of Lux Meters.
While the difference between these two measurements is – literally – easy to see, the similarities are also useful when it comes to understanding the full spectrum. To design an optimum plan for every scenario it's important to understand how these two measurements coincide.Lumen and lux measurements give consumers, governments and businesses the power to illuminate a new world of energy-efficient and powerful light sources. Whether that be used to showcase beauty on the wall of a museum or keep office workers healthy, they are valuable measurements to have. For more information about how Testo's range of Lumen and Lux measurement tools that can serve your needs, get in contact with the Testo New Zealand team today!