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Illuminating a large space takes more than just guesswork, and photometric lighting design ensures that a set of fixtures provides even, sufficient illumination across an entire property. In fact, detailed photometric designs are the only sure way to plan out a large-scale lighting project, whether that project includes a shopping mall, a parking lot, a car dealership or any other sprawling property. But what is photometry exactly? And why is it the preferred method of planning lighting projects?
Photometrics: It’s Complicated
For centuries, people have worked hard to measure light. Of course, handling light is extremely difficult without sophisticated instrumentation, so only recently have experts standardized the process. It gets even more complicated, too, because there is a difference between the actual power of the light and how powerful the light appears to the human eye. The former is measured using radiometry. The latter, photometry, is more relevant to lighting designers.
Photometry, in short, is the science of measuring the perceived power of a source of light. Perception is the key word here, because the human eye is particularly sensitive to certain wavelengths of light, and how it perceives light changes dramatically from day to night. Photometric designs, then, consider the exact wavelengths of light a source puts out and where they will be positioned. This provides a clear picture of what a set of fixtures will look like to a person, depending on where they are standing on the property.
Again, it’s complicated stuff, and it requires a great deal of math to diagram it all out. But where does the math come from?
Over the years, researchers have painstakingly graphed out how the human eye takes in every wavelength of light. This work has provided a standard which lighting designers use. This standard gives lighting designers a deep insight into which lights will be perceived easily, and which lights will be harder to see. For example, lighting designers know that light around 550 nanometers in wavelength (which is green-yellow) is perceived to be the brightest during the day. Unsurprisingly, green-yellow is a standard choice for safety lighting during the day.
Manufacturers Matter Too
In addition to photometric standards, which provide a baseline, lighting designers also have to know what wavelengths of light each fixture will produce. And with dozens of lighting manufacturers, and thousands of fixtures on the market, it’s impossible for a designer to keep all of this information in their head.
This is why the Illuminating Engineering Society, or IES, is so important. The IES studies every lighting manufacturer and every fixture they produce, measuring their patterns and their exact output. This information is stored in files for designer reference.
Together, photometric standards and IES files make detailed photometric plans possible.
Diagramming a Project
A lighting system that is just a little too strong or a little too dim can be off-putting. That’s why it is essential that the system is not just planned and visualized, but mathematically calculated. Experts like LED Spot use modern visualization technology that is intended for quick, 3D planning of lighting projects. The software does all the heavy lifting in terms of math and modeling, so clients know that they are getting a system that is precisely measured out.
Here are a few benefits of using photometry diagramming:
Lighting Precision – The designer knows exactly how far every fixture will emit, and how strong its light will be at certain distances. This is ideal for parking lots and exterior lighting, as it gives designers a clear idea of how tall lighting poles should be, how much power will be required and how many fixtures will be needed.
Safety and Efficiency – Again, for exterior commercial lighting, it is important to maintain a safe level of illumination at night, and photometry makes this possible. For cost efficiency purposes, commercial clients will want to minimize the number of fixtures they use. Photometry ensures that the number of fixtures required for a project is kept to a minimum.
Real-Time Modeling – With modern photometric diagramming, the client can see what their system will look like before it is installed. This way, there are no surprises once the final product has been put in place.
Photometry may be a complicated, technical science, but lighting designers have made it simple in its application. Armed with it, designers can provide clients with a detailed approach to their lighting challenges, and ensure they are met with the best set of fixtures available.