Apr 2019

Understanding LED Light Bulbs


Q: It used to be easy to replace a light bulb; now there are so many options, I don’t know what to choose. What do you recommend?

A: It’s hard to imagine a household commodity that has changed more in the last five years than the light bulb. The incandescent bulbs we all grew up with wasted a lot of energy and have been phased out. Government mandates ushered in the brief reign of the more efficient, but widely despised, compact fluorescent bulbs, or CFLs, which emit terrible-quality light and are difficult to dispose of because of their mercury content. The public’s loathing of CFLs accelerated the development of light-emitting-diode bulbs known as LEDs, which now rule the lighting world. These use up to 80 percent less energy than the old incandescents and can last for decades. LEDs are improving all the time and their prices are coming down. However, the quality of light they produce varies significantly, so it’s helpful to understand some lighting nomenclature before you buy.

Most LED bulb boxes have a Lighting Facts label that indicates brightness (measured in lumens), color temperature (labeled K for Kelvin temperature), energy use, estimated energy costs, and expected life. Since most packages also specify the type of incandescent bulb the LED replaces, you don’t need to pay much attention to the brightness measure. Instead, zero in on color temperature: 3,000K is my recommendation for a universally flattering, warm-white light. Anything higher is going to have a cooler, bluish-white cast. Another good measure is the Color Rendering Index, or CRI, which tells you how accurately the bulb renders colors compared to an incandescent bulb, which has a CRI of 100. For LEDs, a CRI of 80 or higher is best.

To ensure an LED will fit in your fixture, bring your old bulb with you to the store and compare the bases. The splayed fins that LEDs have to dissipate heat make them larger than other bulbs. Make sure the bulb is dimmable (you may need to replace your dimmer switches with LED-friendly ones to avoid annoying flickering or buzzing). And if you plan to use the bulb outdoors and/or in an enclosed fixture (some LEDs require more airflow than these lights provide), check that these applications are noted on the box.

If you haven’t already, now’s the time to embrace this new technology — unlike previous innovations, this one is here to stay.

Oct 2013

Lighting and Color – Why Color Rendering Index is Important

Now that regular incandescent light bulbs are a thing of the past and LED’s and CFL’s are the new “go to” light bulbs, what can you expect your house to look like? The reason I am asking this question is because the colors in your home are going to appear differently than they do under good, old fashioned incandescent lighting. This is because of something know as CRI or Color Rendering Index, a scale of 0-100 where incandescent light bulbs are at the top of scale, 100.

Different light source have different CRI’s, all of which are compared to incandescent light bulbs, but non of which are equal to incandescent. Fluorescent and LED light sources vary in CRI between about 75 to about 85 with some LED’s approaching 90. Therefore things are going to look different depending on the CRI of you light bulb. Note the picture of the fruit and vegetables above. For most purposes, a CRI of 85 is considered good enough in residential applications.
This chart lists different light sources and their associated CRI values. At the bottom of the list is Low Pressure Sodium, a light source that was primarily used in highway lighting in the past. With this kind of lighting, a police officer could not tell the difference between blood and oil at an accident scene. CRI does make a difference!
New light bulb labeling laws are useful in selecting the correct light bulb with a satisfactory CRI. Please see this label and note that in addition to other important information the CRI value is shown as “Color Accuracy”.
Please be advised that higher CRI’s require a higher standard of manufacturing. In a fluorescent light bulb more expensive phosphors must be used and in LED’s higher quality computer chips must be used. Therefore you can expect to pay more for better quality light. There is no right or wrong, just be sure you understand the differences. 
Visit the App Store and download the UL app, LightSmart, for all kinds of great information. And please visit FoggLighting.com and like us on Face Book.