A promising technology but still a ways to go

In my original LED house lights article, which I wrote in 2008, I said that while LED lights were available for the home market, they would probably take a year or two to gain traction. More than two years later, I’m still not convinced LEDs have what it takes to displace the current favorites for light quality – incandescent and halogen lights – or the current favorites for energy efficiency – compact fluorescents.

LED house lights seem to dangle before us the promise of lighting so efficient you can leave every light in the house on and still pay just pennies a month to power them. But when you look more closely you discover LED light bulb replacements aren’t nearly as bright as the bulbs they claim to replace, use a lot more electricity than you might expect relative to their theoretical peak efficiency, and still cost five to twenty times more than a compact fluorescent light of equivalent light output.

In this article I will cover some of the basics of LED lights for homes, issues such as efficiency, reliability, color temperature, and brightness. I’ll describe what types of LED lights for homes are available, both in terms of replacements for standard bulbs, and brand new applications. And I’ll discuss both the aesthetics and finances of LEDs: how much will they improve the look of your home, and how much you will save if you install them. Want to jump straight to one of these sections? Go ahead:

Here’s a quote from the original published version of this article, that unfortunately still holds true today: “I won’t try to sell you on LED house lights as the way out of high electricity bills or as the most environmentally friendly lighting solution around. Frankly I think LED lights for homes have a ways to go yet.” I had hoped that manufacturers would have solved all the quality, brightness, light color, and price problems by now. But it seems they have just made a dent.

Still, there are a few bright signs on the horizon, and a few products that are gaining market acceptance. The LED products I show on this page by way of illustration get generally high customer reviews, and apparently have excellent light quality.

How efficient are LEDs, relative to incandescent, halogen, or fluorescent lights?

LED lights for homes are much more efficient than tungsten incandescent lights. It’s not surprising that a lightbulb invented over 100 years ago scores pretty low on the efficiency scale. A typical incandescent bulb converts about 1.8-2.5% of the electrical energy that flows through it into light; the rest gets converted into heat, halogen incandescent bulbs are about the same, while compact fluorescent bulbs have efficiencies in the 7.0 to 9.8% range. In theory an LED house light can reach a peak efficiency of 38%, which is 15 times higher than what incandescent bulbs deliver in terms of efficiency, or 4 times what a CFL delivers. But current LED house lights are stuck in the 5% to 13% efficiency range. What does this mean? It means that an LED light bulb available today might only be twice as efficient as the incandescent bulb it replaces, and in many cases will be less efficient than a CFL it replaces.

For more information on the relative efficiency of LED, incandescent, halogen and fluorescent lights, see my FAQ page Halogen light energy efficiency where I provide efficiency comparisons of about 30 different commercially available light bulbs. Sadly, of nine LED lights I looked at, only three scored significantly higher than the average compact fluorescent bulb.

Buyer beware! You will see claims of light output on LED bulbs for sale that are at the very least a stretch and in some cases completely misleading. A 2 watt MR16 LED house light I bought recently carried the bold claim on its packaging that it “Replaces a 50 watt halogen light”. Well, that is true because the MR16 bulbs I removed from my basement staircase pot light sockets contained 50 watt halogen light bulbs. And while the LED house lights that replaced them now use much less electricity, they also provide only about a third the light output.

Also be careful of just comparing the rated lumens of LED replacement bulbs to those of regular incandescent bulbs. While lumens comparisons between LED lights and halogen lights can be appropriate, it is almost always wrong to compare the lumens output of LEDs to that of regular incandescent bulbs or compact fluorescent bulbs, for reasons I explain below.

How reliable are LEDs? How long will they last?

If you buy generic incandescent bulbs from your local discount chain you will probably find that the cheapest bulbs are rated for 500 to 750 hours of life, while higher quality ones are rated for up to 1200 hours. Halogen light bulbs are actually no better than incandescent bulbs in terms of energy efficiency. But because the tungsten filament in a halogen bulb is contained inside a small quartz bulb (inside the larger bulb in the case of MR16, PAR20, and GU10 bulbs for instance), the filament tends to last about twice as long as the tungsten in a regular incandescent bulb. When CFLs came on the market, one of the main supposed benefits was that they lasted up to ten times longer than incandescent bulbs, with typical claims being that a compact fluorescent light would last about 8,000 hours instead of 800. My experience hasn’t been so great with CFLs; I’ve had many of them blow after just a few hundred hours, although some have lasted much longer. So I take the claims for LED house lights with a grain of salt.

In theory LED bulbs should last up to 100,000 hours – or more than 100 times longer than incandescent house lights. But there are a couple of caveats to this. First, the longevity we’re talking about here is for the LED itself – the light emitting diode . If you buy a 50-bulb string of LED Christmas lights, each of the bulbs on that string contains a single light emitting diode, and on average each bulb should last 100,000 hours. If one of the bulbs blows after 20,000 hours (which will probably happen about 50 years after you buy the lights!), you can in theory replace that one bulb – or live with it being out – and the others will twinkle merrily for another 200 years worth of Christmases! But in the case of LED lights, a typical replacement LED light bulb is not made of one light emitting diode, but of many. For example, the very dim LEDs in my basement stairwell, which provide (by my estimate) the equivalent light to a 15 watt incandescent bulb, have 22 individual LEDs. Chances are at least a few of those LEDs will burn out before the 100,000 hour theoretical lifetime is reached, which means the lights will get dimmer over time.

To make matters worse, the light output of an individual diode tends to drop over time, with even the best LED house lights falling from 100% to 90% of original light output within 7,500 hours. So even if none of the diodes in your LED house lights blow in your lifetime, the light will fade. (Note that incandescent bulbs and typical compact fluorescent bulbs fade much faster than LEDs; this is not a problem specific to LEDs. I am merely trying to point out that a 100,000 hour theoretical lifetime is just that, theoretical.)

The other reliability issue with compound LED lights such as those that replace conventional house light bulbs is that they consist not only of the diodes but of some fairly complex electronics components.

These three factors – the fact that LED house lights are made up of many diodes, the fading of individual diodes over time, and the electronics component – suggest that most LEDs are unlikely to last anywhere near the theoretical 100,000 hours of a typical light emitting diode. In fact, most product packaging for LEDs only claims longevity in the 20,000 to 40,000 hour range, and even those claims are likely exaggerated for some bulbs. I get at least 2-3 e-mails a month from LED light manufacturers in China wanting me to cover their light bulbs on my website, and this proliferation of new bulbs from companies you and I have never heard of suggest that many of the products on the shelf today are unlikely to last.

How bright are LEDs? Can you get warm white as well as cool white LED bulbs?

Typically, LED house lights are sold in packaging that provides the lumens output of the bulb. For example, the
GE Relax HD Dimmable LED
is a 4 watt bulb that claims 300 lumens of output. But while watts are a straightforward measure of total power consumed by the bulb, lumens are a subjective measure of how much light strikes a particular surface area at a particular distance from the bulb. This leads to a built-in bias that favors narrowly focused beams such as LED beams, versus more diffuse beams such as those of incandescent bulbs and compact fluorescent bulbs. Take a look at this illustration:

Broad vs narrow light output

Broad vs narrow light output

Imagine you are measuring the light output of 3 light bulbs: a broad angle bulb like an incandescent bulb, a somewhat more narrowly focused beam such as a halogen bulb, and a very focused bulb such as an LED flashlight. Each bulb has the exact same light output overall. However, the light meter that measures lumens output (shown as the “M” in each drawing) measures only the light output at a particular point. This means that the broader beam shown at left will register a much lower portion of its light output on the meter, while the very narrow beam on the right will have a much higher proportion of its light output registered by the meter. In other words, LEDs rated at 300 lumens may indeed produce 300 lumens at a point directly below the light if the light shines down. But because an LED light tends to have a very focused beam, it can get a 300 lumens reading at the meter, the same reading as a broad-beam incandescent, while providing far less lighting to surrounding areas.

This is why the rated lumens output of LED lights tends to overstate the light output, and why so many people have been disappointed by the dim lighting that current LEDs provide. It’s also why LED replacement bulbs have proliferated most in the pot light segment of the market. Individual LEDs provide very directed light; an LED replacement light for a GU10, MR16 or PAR16 halogen light tends to have all its diodes pointing in the same direction, so you get a good bright reading directly under the light. But the halogen light it replaces has a more diffuse beam, so a 300 lumens LED pot light doesn’t tend to provide as much actual light as a 300 lumens halogen light.

Manufacturers try to compensate for the very focused beam of LEDs by making LED house lights that have individual diodes pointing in different directions. A light that replaces a traditional incandescent or compact fluorescent light would need to have a beam angle of at least 90 degrees if it is shining down from a ceiling (similar to the light pattern shown at left in the illustration), and this can only be accomplished by orienting the LED diodes across that 90 degree space. Unfortunately spreading the LEDs also means the light output at any given point of the space is typically quite low.

I recently lived for a month in a solar-powered cabin, whose lights were complex LEDs with about 20 LEDs per bulb. When you looked up at the bulbs they were quite impressive – plenty of light coming out, too bright to stare at for more than a second, and only using about 2 watts per bulb. But when you sat down and tried to read a book, it was next to impossible to get enough light to read by, unless you positioned yourself directly underneath where the center of the beam projected, and even then the lighting was less than ideal. I have also heard others complain that a household LED light bulb for which they paid $35 or more, didn’t provide nearly the light they had hoped for, or that the manufacturer’s claims of brightness claimed.

Color temperature is the other issue related to LED brightness. People often complain about fluorescent lights – especially compact fluorescents or CFLs – as having too blue or unnatural a light. In fact, compact fluorescents come in both cool (blue) and warm (yellow) color temperatures. While the bluer shades are actually closer to natural sunlight, the yellow color temperature is what we’re used to from incandescent bulbs. Early LED house lights tended too far towards the blue end of the color temperature range, which turned many people off after their first experimental purchase. There are more options available today, with many LEDs being advertized as having a warm light. One thing to be aware of, as I mention in my separate article on LED under cabinet lights, is that even within a single product, there may be wide variations in color temperature of individual bulbs. To me this is just one more indication that we have a ways to go before LEDs are ready for widespread adoption by consumers.

If you do care about color temperature, then you should know that a typical incandescent light bulb has a color temperature of 2800 Kelvin, with a yellowish tint close to the color temperature of a candle, while natural daylight has a much higher color temperature around 6000K, a color most people are perfectly happy with when out of doors but which can appear too blue in a light bulb. An LED house light in the 5000-6000K range will not be pleasing to most people. An LED light in the 4000K range will look whiter than an incandescent but not so offensively blue. If you can find LED house lights with a color temperature below 4000K you shouldn’t have any issues with the appearance of the light, as long as the light is strong enough.

Personally I am happy to make a little sacrifice in the color of my light bulbs in order to do my part to cut energy waste. That’s why I’ve installed CFLs through much of my house, and a handful of LEDs. If you’re not prepared to make that sacrifice, don’t worry – there will be plenty of ‘warm white’ LEDs hitting the market in the next few years, because that’s what many consumers demand.

What types of replacement LED bulbs are there for standard fixtures?

There are replacement bulbs available for just about every type of common incandescent or fluorescent fixture. The most common replacement LED bulbs are for halogen pot lights, because pot lights typically have a very directed light and LED house lights are ideal for such applications (but again, often not bright enough). LED under cabinet lights are another great application for LEDs because again directed light is what you’re after, and because the cabinets are typically only 18 inches above the counter top you can get by with not that much light.

Regular light bulbs to replace incandescent bulbs are also available. You can even buy LED replacements for T40 fluorescent tube lights, as I mention in Fluorescent garage light.

What are some new LED lighting applications?

Sconce lighting is one growth area for LED house lights. A strip of LED lights can be installed along a sconce around the upper wall of a room, and providing the wall and ceiling above the sconce are painted in a bright color or white, the light will reflect down into the room and provide lots of brightness at little cost. You can do this today with LED rope lights, for example; the challenge is to ensure the sconce ledge is wide enough that the rope lights are not visible from eye height.

These LED ropes can be cut to size, spliced together, and powered from a wall socket, or by a light switch if you are handy with electrical wiring. You can buy kits or the individual parts for rope light installation and as long as you have a bit of experience doing electrical work (remember, make sure the circuit breaker for the circuit you’re working from is turned off!) and are handy with tools, you should be able to do a fair to middling job your first time through.

There are also LED tape products on the market which you just tape to your walls (by removing the plastic backing so that the tape adhesive sticks to your walls).

There is a wide assortment of battery powered LED puck lights, which usually have an adhesive backing. You just peel away the plastic cover on the backing, and stick them on a closet wall or the underside of a closet shelf to provide lighting to an infrequently used space. The main benefit of these lights is it is very easy to install them in an area that isn’t wired for lighting, and a single battery has enough charge to keep the lights on, assuming infrequent use, for several years.

I recently saw a very cool LED house light application, which is a thick sheet of transparent plastic with LEDs running along one edge. The entire sheet lights up and you can cut it to any size you like to create a light fixture on a wall or ceiling or under a cabinet valence.

Dimmable LEDs have been hard to come by until recently, but a few bulbs are beginning to become available that you can install on a standard incandescent dimmer switch. This lack of support for dimming has been one of the big obstacles to adoption of LEDs, especially for pot light applications, so it is good to see dimmable LED house lights coming on the market.

Another great way to get acquainted with LED capabilities is to buy LED candles and spread them around your house. Some of these candles are hard to tell from real wax candles, and with a single battery they can provide light output matching a candle, for many hundreds of hours. Scatter a few LED candles around your living area and you can create a very soft, pleasing light for evening entertainment. We used ours to celebrate Earth Hour this past March.

LED growing lights are another application that makes a lot of sense. Typical fluorescent growing lights use quite a bit more energy than LED growing lights because (A) fluorescent lights are somewhat less efficient, theoretically at least, and (B) fluorescent lights are broad-spectrum, whereas LED growing lights can be tailored to produce light in the particular spectrums plants need for either vegetative growth or flowering.

Will LEDs look good in my home or am I sacrificing beauty for efficiency?

As I hope I have explained above, the current selection of LEDs offers some that are perfect replacements for existing incandescent lights. For example there are under cabinet lights that provide plenty of brightness and a warm white light at a fraction of the wattage of the halogen undermount puck lights they replace, and some LED house lights that replace regular incandescent bulbs offer good brightness and color temperature. But you’ll want to tread carefully if aesthetics is your primary concern. Much of what is now available is not nearly as bright as the product packaging claims, for reasons explained above. And in many cases you will be disappointed with how blue the light from LEDs can be. I recommend always buying one of a bulb to try out before you decide to replace a whole set of bulbs, because you can never be sure how LED lights will look until you try them in your own home.

How long does it take for the higher up front cost of LEDs to be earned back in energy savings?

Obviously, your savings will depend on what you pay for the bulbs, how much longer the existing bulbs would have lasted if you hadn’t replaced them, how much you pay for electricity, and how many hours a day you have the lights on. I would suggest that LED lights should only be installed in rooms where the light is on at least 2 hours a day, if your only motivation is to save money and energy.

The other thing to consider is the rebound effect, something that a 19th century economist William Stanley Jevons postulated as part of the famous ‘Jevons paradox’. The gist of the rebound effect is that any increase in the efficiency by which a resource is utilized tends to increase consumption of the resource. In the case of LED as well as compact fluorescent lights, what I have noticed is that people who switch to these more efficient lights tend to be less inclined to turn lights off when they leave a room, because they don’t think they’re wasting as much electricity as they were with the old lights. The end result is often that the improved efficiency per hour is more than offset by increased hours of use, so the new lights never pay for themselves.

However, if you can remind yourself not to increase usage once you switch to these more efficient light bulbs, then one way to determine the payback period is to use my LED savings calculator. This calculator computes a payback period for you, based on the cost of the lights, their life expectancy, hours of use per day, and cost of your electricity.

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