What Meter Should I Use to Measure Light Intensity?
Lighting professionals use a light meter (also called an illuminance meter or lux meter) to measure the amount of light in a space/on a particular work surface. The light meter has a sensor that measures the light falling on it and provides the user with a measurable illuminance reading.
These handheld devices are commonly used by photographers to help calculate proper light exposure. However, they are also an essential tool that are used to measure and verify light levels in the built environment. Light meters are an especially useful tool if you are measuring light for safety or over-illumination, which cause eye strain and waste energy.
An added advantage of using a lux meter is that they can be calibrated. Why is this important? Consider how one person’s eyesight will determine certain wavelengths of light differently from the next. This means one person could determine a light source as being more or less intense since they perceive, or “see”, certain wavelengths differently. Add to this, different wavelengths emit different intensities of light.
This is why lux meters are configured to CIE standard illuminant A. A standard lux meter is essential to measure incandescent lighting, but what about LED lighting? To measure light intensity from LED lighting, you would use an LED light meter.
LED lighting has become increasingly common in commercial environments because of energy-efficiency, longevity, color temperature tuning, safety, and low maintenance. But LEDs produce white light in a different way to incandescent or fluorescent lighting, so it’s important to use the correct meter.
How to Measure Light Intensity Using a Light Meter
Using a light (lux) meter is the best way to measure light intensity – it gives us the ability to choose the optimal light intensity for an environment.
1. Measure Ambient Light In the Room
To begin, turn off any lighting in the room you’re about to measure. Turn on the light meter to establish what’s known as the baseline measurement – the ambient light.
This means you’re able to see how much the existing lighting adds to the room once the lights are then turned on.
2. Turn On the Lights, Take Your Measurement
From a central area of the space, ensure your light meter is set up to record your new reading. Remember not to rush – allow the lighting a few moments to reach full brightness (especially if you’re measuring light from CFLs).
3. Note Your Differential Reading
Simply subtract the ambient light level from the illuminated level – known as the differential (or delta) measurement, this is the amount of light the existing luminaires produce. With this light measurement unit, you can asses how it compares to the optimal lighting levels required.
4. Check Other Areas of a Room
For open office lighting or a corridor, the reading you get from your light meter should, in theory, be consistent. However, it might be worth checking any potential “blind” spots just to be sure you have consistency.
How Light Intensity Affects Functioning
Light intensity affects the way humans live, work and interact. More recently researchers have discovered how light affects our health and well-being. Research has shown that while standard artificial light meets our visual needs, it is not sufficient to provide proper biological signals that our bodies and brains need and can even have a negative impact on our long-term health. The reason being, people now spend the majority of their lives indoors – we’ve lost our connection to the sun and the solar day and no longer receive the critical light signals our bodies and brains need to promote better sleep and daytime alertness. We live in indoor environments that are too dim for our brains to identify as daytime and too bright at night for our brains to recognize as nighttime. We’ve lost our tie to our natural circadian cycle. For example, think about the brightly-lit grocery store you go to late in the evening or the dim lecture hall or conference room you might spend the middle of your day – this is completely the opposite of the light signals around which our bodies evolved.
Our modern lifestyles have reached the point where most of us spend around 87% of our time indoors. This means most of our “daylight” exposure is provided almost entirely by artificial lighting.
Without proper daylight exposure and because we remain more active in brighter environments at night, our sleep-wake cycles, which are directly linked to our circadian rhythms and melatonin production (the key sleep hormone) – become dysregulated. In order to get adequate and restful sleep which promotes daytime wakefulness and increased energy levels, mood and productivity; we need a well-functioning circadian rhythm. When this happens, we have improved sleep quality, allowing our circadian systems to repair both our bodies and our minds.
Studies have also shown that proper daytime light signals also affect serotonin (1), the precursor to melatonin. Serotonin helps us feel positive, calm, and productive – something we get from adequate daylight exposure and it is why Seasonal Affective Disorder (SAD) is such an issue throughout the extended darkness of our winter months!
The same study on the ‘Benefits of Sunlight’’ explains:
“The light we get from being outside on a summer day can be a thousand times brighter than we’re ever likely to experience indoors,” says melatonin researcher Russel J. Reiter – University of Texas Health Science Center.
“For this reason, it’s important that people who work indoors get outside periodically, and moreover that we all try to sleep in total darkness. This can have a major impact on melatonin rhythms and can result in improvements in mood, energy, and sleep quality.”
When we have access to sunlight each day, we’re healthier for it which means better outcomes for people and businesses – a company’s workforce that is well-rested at night is healthier, happier, and therefore more productive. Think about a time you’ve gone camping, hiking, or just spent the entire day outside – many times we find ourselves able to sleep better and more soundly after those experiences.
