Color Temperature Explained

May 11, 12 Color Temperature Explained

Every light source has a distinct character, from the warm, dim glow of a candle to the blue, bright beam of a street light. Brightness, measured in lumens, is one part of that character; the other part is color temperature. Measured in degrees Kelvin, color temperature is not the ambient hot/cold temperature of our surroundings. In fact, the Kelvin scale goes backwards: The higher the color temperature, the cooler light gets, and the lower the color temperature, the warmer light gets.


Warm Color Temperatures (2000K to 3500K)

Lighted Makeup Mirror

Lighted Makeup Mirror

Most homes look best in warm-toned light. This is for several reasons, but the first one is a home’s color scheme. People tend to decorate homes in warm earth tones—reds, oranges, and yellows—which warm light enhances. In addition, people tend to look better in warm light. If your grandmother had a lighting makeup mirror with adjustments based on “office,” “home,” and “evening” lighting, you may remember that you looked a lot better in “home” and “evening” modes than “office” mode. That’s because (you guessed it!) those modes had lower color temperatures than “office” mode.

Cool Color Temperatures (4000K to 4500K)

While warm color temperatures are the residential standard, some people prefer higher or “cooler” color temperatures. Because of their neutral tone, it’s common to see color temperatures of 4000K or higher used as task lighting  in offices. Moreover, people often perceive higher color temperatures to be brighter than warm temperatures, while others feel cooler light looks “cleaner.” Finally, higher color temperatures can enhance homes with cooler color schemes, especially those with a lot of blues and whites.

Full Spectrum Color Temperatures (5000K to 6500K)

Less common are very high color temperatures, often referred to as “full spectrum” or “daylight.” Color temperatures of 5000K to 6500K approximate the color of light outdoors on a bright, sunny day. The cast of the light can be a very pronounced blue and can seem harsh to some people. It’s unlikely to see color temperatures of this range in homes, though there is a trend of installing “full spectrum” bulbs in offices as they are sometimes associated with higher productivity.

Making a Decision

There’s nothing that can sour your opinion of CFL or LED lighting like buying a 4000K or 5000K bulb when you meant to buy a 2700K bulb, or vice-versa. When you buy a new, energy efficient bulb, keep your application and color scheme in mind and make sure to buy the bulb with a color temperature to match.

So do you prefer warm or cool color temperatures in your home? Have you ever mistakenly bought a bulb of the wrong color temperature? Share your thoughts and experiences in the comments section below or contact us on Facebook, Twitter, or Google+.

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How Many Lumens Do I Need?

Apr 13, 12 How Many Lumens Do I Need?

If you’ve been to a home improvement store within the past 6 months, you’ve noticed household incandescent bulbs have given way to new, sometimes unfamiliar technologies. You may find a couple “full spectrum” incandescents or Halogen floodlights, but other than those, compact fluorescent and LED bulbs line the shelves. Long gone are the days of throwing your favorite brand of 60-watt light bulb in your cart and being on your way. No, you may not even be sure which funny-looking 60-watt equal light bulb you need.

Before buying a CFL or LED light bulb, get rid of any notions you have about incandescent equivalencies. How many times have you bought a 60-watt equal CFL or LED only to be disappointed by how dim it was (or blinded by how nauseatingly bright it was)? Because there is no agreed-upon standard among manufacturers for determining equivalent wattages, statements of incandescent equivalency for CFLs and LEDs are not always dependable. So to light your home the way you intend, stop thinking about watts and start thinking about lumens.

If you read our previous article on lumens, candlepower and CRI, you may remember the definition of lumens. If not, here’s the gist: “Lumens…represent the actual amount of ambient light coming from a lamp. The higher the lumens, the more ‘lit up’ a room will be.” However, while a definition of lumens is nice, if you’re like us, you’re probably asking the real question, “How many lumens do I need to light up my room?” The answer will vary based on the design and color scheme of your room, but here is good rule of thumb, loosely based on the IESNA Lighting Handbook:

Floors: 20 Lumens per Square Foot

Tables and Raised Surfaces: 30 Lumens per Square Foot

Desks and Task Lighting: 50 Lumens per Square Foot

For the average living room of 250 square feet, you’ll need 5,000 lumens as your primary light source (20 lumens x 250 square feet), equivalent to about five 100 watt incandescent light bulbs, five 23 watt CFLs, or eight 10 watt LED light bulbs. Since you probably read on your couch, you’ll also need about 4 square feet of task lighting on each end of the couch. That’s 200 lumens each (50 lumens x 4 square feet), but you’ll need more if the light source is a lamp with a shade. In your dining room, you’ll want about 30 lumens per square foot on your dining table (you want to see your food, but not examine it), so if your table is 6 x 3 feet, that’s 540 lumens.

Room Layout

Create Your Own Room Layout at

Keep in mind, however, that these numbers are for typical conditions. If you have especially dark walls and furniture, you’ll need brighter light sources. The distance of your light source from the surface also changes the equation. We based our calculations on 8-foot ceilings and average height task lamps. Finally, personal preference will play the largest part in your decision. If you like the room to be especially bright, you may want to add 10 to 20% to our numbers. In fact, the best idea for any home may be to aim high and install dimmers to bring the light level down to where you want it.

So how much have you thought about how many lumens you need for your home? Are our numbers too high or two low? Let us know in the comments below, on our Facebook or Twitter, or even post a photo of your home on Pinterest and share it with us!


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How Do Infrared (IR) Halogens Save Energy?

Apr 06, 12 How Do Infrared (IR) Halogens Save Energy?

In a recent article, we discussed the impending phase out of Halogen PAR lamps. One of the technologies we listed as a replacement was Infrared (IR) Halogen. But what is an IR Halogen, and how does it save energy? To answer that, let’s first do a brief refresher on freshman physics.

Visible light is only one part of the electromagnetic spectrum, which in its highest frequency includes gamma rays and in its lowest frequency, microwaves. Somewhere in between is visible light, which itself is sandwiched between higher frequency ultraviolet rays and lower frequency infrared rays. (For those of you who like videos, check out the Electromagnetic Spectrum Song on YouTube for more detail.)

Electromagnetic rays aren’t neatly delineated like they’re shown in textbooks but instead, tend to “bleed” together, with visible light also including some UV and IR rays. When a light source ventures into the UV rays’ territory, the light may fade clothing, paintings, and anything sensitive to UV. Similarly, when a light source ventures into the infrared spectrum, infrared heat overwhelms visible light. This “bleeding” is why incandescent bulbs are so inefficient. Ever try to unscrew an incandescent light bulb when it’s been burning for an hour or so? It’s hot, isn’t it? That’s because as much as 90% of the electromagnetic rays produced by an incandescent bulb are in the form of infrared heat; only the remaining 10% is visible light.

Halogen light bulbs are a tweaked form of incandescent bulbs that are slightly more efficient. Nevertheless, they still waste energy in the form of UV and infrared rays. For this reason, manufacturers started adding dichroic coatings to Halogen lamps (especially MR16 bulbs) so that they redirected heat and infrared through the back of the bulb instead of the front, reducing possible damage to the object lit by the lamp. Still, this only protects the work of art, retail display, or whatever object at which the user aims the lamp. It doesn’t do much, if anything, to reduce energy consumption.

GE HIR Plus Table

HIR PAR Lamps Save 40%

From there, manufacturers developed a new idea: Why not coat the Halogen capsule within the bulb? The result is an IR Halogen, in which the infrared heat coming from the bulb filament is redirected right back on the filament, causing it to burn hotter and brighter while still using the same amount of electricity. In other words, a 60 watt Halogen bulb (for example)  when given an IR coating to its internal capsule, is bright enough to equal the light output of about a 90 watt Halogen.

So just how much energy do IR Halogen PAR lamps save? The rule of thumb is about 40%. Sylvania’s 50 watt IR PAR38 (130V), for example, produces 850 lumens, equivalent to a standard 130V Halogen PAR38 of about 75 watts. A savings of 25 watts is very significant, especially considering even small retail shops can be running as many as 100 PAR38 bulbs at a time. The savings over an incandescent PAR38 or R40 are even more dramatic—as high as 60%. For a more detailed wattage equivalency, check out the chart from GE to the right.

IR Halogen bulbs also have an indirect benefit on energy usage: Since the coating puts the wasted infrared energy to use by redirecting it inward and transforming it to visual light, the total heat emitted by the bulb is reduced, lightening the load on HVAC systems.

IR Halogens are now available in most Halogen bulb types, including IR PAR20 bulbs, IR PAR30 bulbs, IR PAR38 bulbs, and IR MR16 bulbs. Our advice would be to switch over now, even though the phase-out isn’t yet in effect. Why? If you wait and hold on to your less efficient Halogens, you’re throwing away money on wasted electricity!

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How to Identify Your Reflector Light Bulb

Feb 24, 12 How to Identify Your Reflector Light Bulb

Before CFLs and LEDs, most people referred to reflector light bulbs simply as “flood lights,” or even less correctly, as “halogens.” Only designers and commercial lighting installers knew bulb shape jargon like “PAR30″ and “BR40.”

For better or worse, that’s no longer the case. Since the advent of more energy-efficient lighting technologies, selecting a light bulb has actually gotten more complicated, often requiring everyday customers to know specialized bulb terms. No longer can you unscrew a burned out bulb, take it to the local hardware store, and pick the bulb’s exact match. Now you have to ask yourself not only “What is this?” but also “What replaces this?”

Fortunately, learning the terminology and selecting the right bulb is easier than you might think.

R-Type Bulbs (R20, R30, BR30, R40, BR40)

If you’re replacing a bulb inside your home with a diameter between 2-1/2 and 5 inches, you’re likely looking for an R-Type bulb. They’re what you usually see in kitchens, living rooms, and media rooms, especially in recessed cans. R-Type bulbs have a frosted face that evenly diffuses light and eliminates glare, but unlike a PAR bulb (explained next), the entire bulb envelope (lighting nerd speak for the outside of the bulb, not including the base) is made of blown glass. The outside of the bulb is completely smooth, and the bulb is relatively lightweight since it only consists of thin glass, a filament, and a brass base.

Because LED replacements for R-Type bulbs are rare and CFL replacements are much more easily found, let’s focus on CFLs: To identify the CFL replacement you need, select an R-Type bulb based on its diameter. All light bulb diameters are referred to in eighths on an inch, so if the diameter of your bulb is 20 eighths of an inch (2-1/2 inches), you’ll need an R20 CFL. If your bulb is 30 eighths of an inch in diameter (3-3/4 inches), you’ll need an R30 CFL, and so on.

PAR Bulbs (PAR20, PAR30, PAR38)

If you’re replacing a reflector bulb on the exterior of your home with a diameter between 2-1/2 and 4-3/4 inches, you’re most likely looking for a PAR bulb. Unlike R-Type bulbs, PAR bulbs feature an aluminum reflector with a special pattern of impressions that amplifies and concentrates light in a single area. The bulb envelope is made of two pieces: The glass face and the shiny aluminum wall of the envelope. The texture of the bulb will be either rough or textured and the bulb will be heavier than an R-Type bulb due to thicker glass construction. PAR bulbs are also used indoors, especially in track lights; in a pinch, they’ll work just fine for recessed lighting as well.

Both LED PAR bulbs and CFL PAR bulbs are easy to find, though they aren’t always weatherproof like traditional halogen PARs, so be sure to check their UL listing before installing them outdoors.  You can determine if you need a PAR20, PAR30, or PAR38 based on the bulb diameter in eighths of an inch, just as you would with an R-Type bulb.

An Exercise in Reflector Bulb Identification

A reflector bulb in your living room has just burned out. It’s in a recessed light. When you remove it, you notice that the sides are smooth and the bulb is surprisingly lightweight. When you measure the diameter, it comes out to 3-3/4 inches. What is it? If you guessed it’s an R30, you’re right. Now what do you replace it with? If you guessed a CFL R30 or an LED PAR30, you’re also right!

If you can’t identify your bulb, no worries! Feel free to describe it in the comments on our blog, post it on the Facebook wall, or ask us about it on Twitter using our handle @1000bulbs.

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Buying Fluorescent Ballasts: 3 Factors to Consider

Feb 10, 12 Buying Fluorescent Ballasts: 3 Factors to Consider

Unless you’re an electrician, you’ve probably never changed a ballast. Chances are, when your garage fixture or kitchen light went out, you changed the bulbs, and when that didn’t work, you went to an overpriced hardware store and bought a brand-new fixture. Sound familiar?

Unfortunately, you could’ve saved a lot of money by switching out the ballast—an investment of only $10 to $15.

But with so many options out there, how would you know which ballast to pick? The truth is, it’s pretty simple. There are tons of fluorescent ballasts to choose from (we have nearly 300 on our site!), but most business owners and even homeowners will find it easy to wade through that seemingly never-ending selection if they concentrate on just 3 key specs: Bulb type, start method, and ballast factor.

Bulb Type

Needless to say, this is the most important part. If you don’t know what type of fluorescent bulb you’re using, you’re going to have a hard time figuring out which type of fluorescent ballast to buy. Fortunately, most fluorescent fixtures will use one of three common bulb types: An F40T12 (4′ long; 1.5″ in diameter), an F32T8 (4′ long; 1″ in diameter) or an F54T5 (46″ long; 0.625″ in diameter). If your bulbs don’t meet one of these descriptions, you’ll need to check the etching near one of the ends of the fluorescent bulb (a good idea even if you think you know the bulb type).

Start Method

Once you’ve determined what type of  fluorescent bulbs you have, don’t burn them out prematurely by choosing a ballast with the wrong starting method. As discussed in a previous article on how to extend the life of a light bulb, an instant start ballast hits the fluorescent bulb cathodes with about 600 volts every time you flip the light switch. As you might imagine, the bulb can only stand so many of those on/off switches. Consider where your fixture is installed. Offices, boardrooms, and retail spaces tend to stay lit for long periods, so use an instant start ballast should be fine, as long as you don’t switch the lights off and on more than about 3-4 times a day. Hallways, stairwells, and bathrooms are switched much more frequently, especially since the lighting in these areas is often controlled by an occupancy sensor. In these areas, it’s best to use a programmed start ballast, which will heat the bulb cathodes more slowly and prolong its life.

Ballast Factor

Finally, you need to consider light output. “What?” you say. “You mean the bulb isn’t exactly the brightness it says it is on the label?” Nope. The light output shown on a fluorescent bulb’s label, expressed in lumens, is figured using a normal light output ballast with a ballast factor between 0.77 and 1.1. A normal ballast factor is usually the right option, for “normal” circumstances. But if you don’t need your room quite as bright, you can save electricity by using a low output ballast with a ballast factor below 0.77. On the other hand, if you are lighting a warehouse or manufacturing facility where brightness is important, you will need a high output ballast with a ballast factor above 1.1, which will push the bulb to be 10% or more brighter than stated on the label.

Of course, if you need something more specialized like a sign ballastdimming ballast, or circline ballast, you’ll likely need an equally specialized electrician. The same principles still hold true, however, so if you need to call an electrician, at least he’ll be impressed by how much you know!


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Understanding Life Hours, Part 3: How to Extend the Life of Your Bulbs

Jan 27, 12 Understanding Life Hours, Part 3: How to Extend the Life of Your Bulbs

The third and final part in a series about life hours and how you can use this spec to inform your purchase and maximize the life of your bulbs.

If you’re a lighting nerd like most of us at, you’ve likely heard of the 110-year-old Centennial Bulb in Livermore, California. If (more likely) you’re not a lighting nerd, here’s the brief rundown: The Centennial Bulb was installed in a firehouse over 110 years ago and still hasn’t burned out. It’s not known exactly how it has lasted so long, but there are a few good clues: One, it has only rarely been moved; two, it has been switched off only a handful of times, and three, it is operated at very low power.

The two previous articles in this series explained how manufacturers determine life hours and how life hours and warranties are two different things. This third and final article in the series explains how you can make your light bulbs last longer. We can’t guarantee they’ll last 110 years (in fact, we can almost guarantee they won’t), but by following a few tips you can easily double or triple the life of your bulb. One caveat, however, because not all light bulbs use the same technology, these tips do not apply to all bulbs.

Don’t move it! Light bulbs get hot. Really hot. And when metal (which makes up a bulb’s filament) gets hot, it gets brittle. The more you handle a bulb with a brittle filament, the more vibration you subject it to, making the filament much more likely to snap. This doesn’t apply only to handling the bulb; it also applies to placement. Any bulb installed in a place that moves also moves. The swish of a ceiling fan or the slam of a refrigerator door, while barely heard by you, is a light bulb’s death knell. It’s for this reason that you may have seen special bulbs with reinforced filaments marketed as “ceiling fan bulbs” and “appliance bulbs.” As you might have picked up, this rule only applies to bulbs with filaments, like incandescent and halogen bulbs.

Leave it on! This may sound contradictory to common sense, but it’s not. Every time you flip a switch, you are blasting your light bulb with power. That poor little filament is forced to go from room temperature to 5000° F in a fraction of a second! You do that too many times, and the filament will literally crack under the pressure. This also goes for ballasted bulbs like linear fluorescents, CFLs, and HID lamps. In the case of an instant start fluorescent ballast, you’re hitting the fluorescent tube cathodes with 600 volts every time you flip the switch. After so many power cycles, the lamp will fail. Keep in mind, however, that while this trick will prolong the life of your bulb, it could also increase your electricity usage.

Operate it at low power. This may be the real secret to the Centennial Bulb’s longevity. Less power means less heat, which translates to less stress on a bulb filament. If you live in the United States, your house is operating on ~110V, so if you buy a bulb rated for 130V, you’ll be hitting the bulb with 15% less power than it is designed to handle  (130V – 15% = 110.5V). You can stretch this principle even further with a dimmer switch. When you dim a bulb, you are lowering the voltage delivered to the bulb filament, putting it under less stress. This also applies to fluorescent technology, but in a slightly different way: Unlike an instant start ballast, a programmed start ballast supplies a much lower starting voltage and heat to the lamp.  If you switch to this type of ballast, you could extend the life of your fluorescent bulbs by over 30%.

Finally, remember that the aim of extending bulb life, in most cases, is to save money. Is it really worth it to make that incandescent bulb last forever by dimming it and leaving it on for longer periods? In many cases, it’s better to switch to a more efficient CFL or LED. But if you’re a die-hard incandescent fan, or want to recreate your own Centennial Bulb, these tips will come in handy.

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