As people look at making the switchover to LED bulbs, a question that comes up quite often is how to choose the right bulb to produce a comparable amount of light to the bulb being replaced.
Generally, the easiest way to solve this problem is to find a product where this work has been done for you already. For example, almost all CFL bulbs list an incandescent wattage equivalent, so if you're looking to replace a 60 watt incandescent bulb, you can simply look for a CFL that is listed as a 60 watt equivalent. Unlike CFLs, however, many LEDs do not list incandescent equivalencies at this point. There are a few reasons for this. Many manufacturers wanted to continue testing light output over time, or have been waiting for their ENERGY STAR certification before advertising an incandescent equivalent.
This brings up a larger question about lighting equivalencies, and truthfully it can be a difficult question to answer. Here are some factors to consider:
Lumen measurements can be helpful when comparing bulbs. However, it's important to note that lumens are measured at the source. What matters much more is the amount of light that is landing in the area you need lit, and quality LED bulbs have proven to be quite effective at this task. We are now regularly seeing LEDs outperform incandescent and halogen bulbs with higher lumen ratings.
For example, we recently tested a 16 watt LED and a 75 watt halogen as part of an article on the importance of using quality product, and we measured the lux (lumens per square meter) at a distance of 12 feet. The LED is listed at 600 lumens, while the halogen is listed at just over 1000 lumens. However, when we measured the landed light, the LED outperformed the halogen to the tune of over 60%:
| Philips 16PAR38 LED |
75 watt halogen PAR38 |
| 368 lux |
233 lux |
As you can see, the LED is doing a much better job of landing light, and that's what really matters in practical application.
Another thing to consider: Our eyes are not light meters. Even if the actual lumen output is identical, factors like Color Temperature, and Color Rendering Index (CRI) can make one light source appear to be brighter than another.
Color Temperature (Kelvin)
An expression of the hue of the light emitted, measured in degrees Kelvin. Usually expressed by a four digit number followed by (k), such as 2700k. Higher temperatures indicate whiter, "cooler" colors, while lower temperatures indicate yellower, "warmer" colors. Some common Kelvin temperature benchmarks are 2700k (warm white), 3500k (neutral white), 4100k (cool white), 5000k (bright white), and 6500k (daylight).
CRI
Color Rendering Index is an international system used to rate a lamp's ability to render object colors. The higher the CRI (based upon a 0-100 scale) the richer and more accurately colors generally appear. CRI differences among lamps are not usually visible to the eye unless the difference is more than 3-5 points.
Ultimately, the best thing to do if you're interested in LED lighting is to try one, or a couple, out. These bulbs are ready to use in many general lighting applications, and it's the perfect time to see them in action for yourself. If you're interested in being able to quantify the differences, you may even want to consider purchasing a lux meter, which can cost as little as $20-30.
Still have questions? Call and talk to one of our Lighting Specialists at 888-455-2800.
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