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By Lois I. Hutchinson

Editor, Elemental Green

There’s a reason Easy Bake Ovens used to use a 100-watt light bulb. Incandescent light bulbs wasted so much energy putting out heat that you could actually cook with them. Inefficient incandescent bulbs—or lamps, as they are called professionally—have fallen by the wayside as more and more people look to save money on energy and reduce their eco-footprint with LED light bulbs. In fact, many inefficient lamps are banned by law in several states.

A typical home now uses more appliances and electronics than ever, but average energy use per household is trending down due, in part, to high-efficiency devices like LED light bulbs. The newest LED technology is approaching maximum efficiency: the theoretical point where every scrap of power that goes in produces light power coming out.

Compact fluorescent lamps (i.e, CFL light bulbs) were an energy-efficient alternative at the turn of the twenty-first century, but they presented potential health risks in the home. CFL’s ultraviolet light emissions could be hazardous when used close-up like in a desk lamp, particularly to certain sensitive individuals. Plus, the presence of mercury in CFLs requires careful handling and recycling, and elaborate cleanup precautions when bulbs are broken. There are many bulb options out now where LEDs have bases engineered to replace CFLs. This is a good thing to do when the opportunity arises. Please be sure to recycle CFLs per your local regulations.

LEDs use even less energy than CFLs, last longer, and do not contain mercury, making them king of the counter in the lighting department. Newer home lighting fixtures, such as downlight cans and undercabinet lights, may not have replaceable bulbs at all. The LEDs are hardwired in, so when the product fails after many years, the entire fixture is recycled. This can allow a lot of freedom in designing fresh, modern chandeliers and desk lamps. And they might provide better lighting for your space at a reasonable price premium.

But let’s stick with LED light bulbs. As the technology improves, LED light bulbs that were once very expensive can be had for $5 or less. The savings in energy cost, year after year, pays for the investment many times over.



Annual energy cost of LED bulb is one-fifth of incadescent

Comparison image courtesy ENERGY STAR.

An LED light bulb’s energy efficiency is usually measured by how many watts it requires compared to the traditional incandescent light bulb we might be used to. For example, comparing a 60-watt traditional incandescent bulb that we might have used in a hallway ceiling or plug-in table lamp: we can expect an LED replacement to consume about 10 watts and produce a comparable amount of light. A 100-watt incandescent lamp providing lots of light in a kitchen or garage would be replaced by an LED at about 17 watts. Choosing a product that is just a few watts less than another is far less important than choosing a high-quality product.

Energy Star sets light output requirements for a “comparable to 60-watt incandescent” or “comparable to 100-watt incandescent” light bulb; along with minimum efficiency standards. Light output is measured in terms of “lamp lumens” and the efficiency, referred to as efficacy, in terms of “lumens per watt.” These are parameters of the light bulb itself and do not reference how much light you will get out of the light fixture you are putting it in. Lenses, shades, and mounting positions all affect “delivered lumens,” which is a topic for another day.

Energy Star also sets performance standards for reflector light bulbs. These are the R, BR, and PAR lamps that you might use in an outdoor floodlight or in a recessed downlight in a high livingroom ceiling. Instead of sending light out in all directions, reflector light bulbs send light in a single direction. Quality reflector light bulbs are highly directional, without a huge spread of light or brightness spilling out at the top. There are all sorts of light bulbs now available in energy-saving LED. Decorative filament bulbs are one of the hottest trends, but might not be tested for efficiency and longevity.

The Energy Star label ensures that an LED light bulb has been tested and proven to live up to a whole host of performance measures: brightness, instant-on at the flick of a switch, energy efficiency, consistent light output over time, lack of visible flicker, and an absence of general color weirdness. After all, a light bulb isn’t efficient at all if you hate it and get rid of it.


Assuming the light is burning for at least 3 hours a day, a traditional incandescent bulb lasted about a year before it needed replacing. Quality LEDs can be expected to last at least 15 times longer. In fact, some may never burn out. They’re so tough that they will gradually fade in light output until they’re just not producing enough light and need to be replaced. The Lighting Facts label that you’ll find on the LED light bulb’s packaging lists “rated life,” which statistically is the time (in burning hours) it should take before half of the light bulbs of that make and model burn out.

Again, whether an LED light bulb is “rated” to last 23 years versus 20 years for a comparable product is not particularly relevant. It is far more important to choose a quality product from a manufacturer that will stand behind its warranty in case a defective light bulb burns out or fades early. Look for the Energy Star label to ensure that your minimum warranty is 3 years.

Because LEDs last many times longer than previous light bulb technologies, they reduce your household waste stream. Remember that when they do burn out, or start fading in light output significantly, LEDs contain semiconductors and must be recycled as e-waste.


Colors of White LED light bulbs

Perhaps you’ve already brought home an LED replacement bulb, turned it on, and felt like you’ve stepped into a refrigerator. Unlike traditional incandescents that produce familiar, warm-white light, different LED light bulbs produce different tones of white light: from cool-looking, daylight-blueish white to toasty-looking, candlelight-yellowish white. A light’s color is defined by correlated color temperature (CCT), which makes sense, measured in degrees Kelvin (K). But the scale is upside down: a high CCT of 5000K appears much bluer-colder than a toasty low CCT of 2700K. For household use, you generally want a warmer “Light Appearance,” as it’s defined on the Lighting Facts label; in the neighborhood of 2700K–3000K depending on your decor. Reserve cool, 4000–5000K light bulbs for places that need a daylight look: high-energy workout rooms, garages, or security lighting.
LED light bulbs come in differnt colors of white light

Lichtsegel LED Tunable White image by Claudia Angerer licensed under CC BY-SA 4.0

If you remember the prism lesson from middle school, you know that sunlight contains all the colors of the rainbow, which allows us to see all the colors in the world. Incandescent light is the same, though it will show us some colors (reds) more strongly than others. LEDs make white light in a few different ways, but this continuity in how colors appear to us is very difficult to replicate. You may find a store dressing room that makes a teal look bluer than it looks outdoors. Or a restaurant that gives your dining companion, and you, a Night-of-the-Living-Dead pallor. Color Rendering Index (CRI) is the metric for how light shows, or fails to show, lots of different colors accurately. Incandescent gets a perfect score of CRI=100. Energy Star will put its label on LED light bulbs at 80+ CRI; but the latest LED technology should offer you 90+ CRI.


LED light bulbs normally do not dim and will not operate properly on a circuit with a dimmer. Some LEDs marked “Dimmable” contain electronics that will respond to a standard incandescent-type dimmer, but they can be finicky and may still flicker or shimmer. Many LED replacement bulb manufacturers publish lists of specific dimmers that are compatible with specific LED light bulbs.

Even with a compatible light bulb–dimmer configuration, you will not see a progressive warming of the light’s color as it dims down to candlelight levels. Look for “dim-to-warm” or similar labeling for products that will emulate the way that incandescent light bulbs warm in color as they dim down.

Color-tunable LED light bulbs take advantage of LED technology to both dim white light and shine in brilliant hues of your favorite colors. They require a special controller or app and are attached to your household wifi or smart home system. Though they’re fun, they likely do not offer the benefits of long life and energy efficiency that have made LED light bulbs the clear choice for the future of our planet.

How to read a Lighting Facts Label infographic
Infographic courtesy Cree Lighting