Is an Incandescent Light Bulb Energy Efficient?

We live in the age of the CFL (compact fluorescent lamps) and the LED (light emitting diodes). The U.S. government has long since pressed for the elimination of the incandescent light bulb. It all but ordered their complete replacement, while also encouraging financial incentive programs for more energy-efficient residential lighting. Be that as it may, the incandescent light bulb is a resilient little piece of technology. And even though, when it comes down to paying your electricity bills, incandescents do cost more, they also come with a slew of undeniable advantages:

• They’re cheap upfront, mainly because they have low production costs;
• They work just as well on AC and DC (alternating and direct current);
• You don’t have to wait for them to ‘warm up’ and light up after you turn them on;
• They come in virtually all shapes and sizes;
• The colors are warm, easy on the eyes, and hold out great throughout the bulbs’ lifespan.

After all is said and done, though, the problem remains that incandescent light bulbs are neither good for the environment, nor for your bank account. To learn more about them, check out our list of facts and definitions below.

What is an incandescent light bulb?

They are called by several names: incandescent light bulb is one of them, but lamp and light globe are also among the terms used to describe them. Here’s a simple definition of the incandescent light bulb: The incandescent light bulb is a light fixture powered by electricity, which heats its wire filament up to high temperatures, until its glow (or incandescence can be seen). How do incandescent light bulbs work? As described above, the essential process is heating the filament with electricity. Then, it’s also important that the filament doesn’t oxidize—for this reason, it is covered by a bulb-shaped housing, made of glass or quartz. Inside that bulb, there’s inert gas or a vacuum. The socket, located at the other end of the bulb, is what connects it to the electricity and also supports it mechanically. How do halogen lamps work? The brief answer is that they’re close cousins with incandescents. The process is basically the same, with one major difference: metal is redeposited on the filament and thus helps it last longer. Halogen light bulbs receive electricity via the terminals/wires embedded in the glass.

Types of incandescent light bulbs

Also known by the name of A-line lamps, there are three main types of incandescent light bulbs still in use in homes around the world today:

• Standard incandescents. These are the regular, less energy efficient A-line lamps, also known as screw-in lamps. The typical bulb in this category comes with a medium-sized Edison (E-26) base. A special sub-category here is the so-called long-life lamp, which has a sturdier filament. Despite the fact that they last longer, though, they’re also even less efficient than regular bulbs in terms of energy consumption.
• Halogen lamps. These are also dubbed energy-saving, because of their halogen gas content, which prolongs the lifespan of the bulb, but also because of their special inner coating, which brings the heat emanated by the bulb back inside. In other words, these rather more expensive light bulbs recycle the heat, which would otherwise go to waste. Halogen bulbs do a great job at accurately reproducing colors and they also require less electricity to keep the filament hot.

Some halogen lamps can be used with dimmers and timers. Many of them are used as reflectors (spot lights, flood lights), as well as in recesses and other fixtures.

• Reflector lamps. These are also called Type R bulbs. Since they directly shine their light over specific areas. Because of this, they’re generally used as flood lights, spot lights, and downlights, both inside and outside homes. There are two different types of R lamps:
  1. PAR lamps. The acronym stands for Parabolic Aluminized Reflector Lamps. They are typically used as floodlights outdoors.
  2. ER lamps. Ellipsoidal reflector lamps shoot their rays of light some two inches before the enclosure and thus shine the light down. This makes them twice as good for recessed fixtures as the PAR lamps described above.

Image source: Earth LED

Incandescent light bulbs today

Is there an incandescent light bulb ban law?

While incandescent light bulbs haven’t been banned per se in the United States, they have recently been “phased out”—which is just a more polite way of saying they’ve been gradually replaced with more energy efficient alternatives. The same goes for the European Union, Canada, and China. Meanwhile, in other places around the world, incandescent light bulbs have actually been banned from sale. Such countries include Mexico, Cuba, Colombia, Argentina, Australia, and Brazil.

Can you still find incandescent light bulbs for sale?

As of January 1, 2014, standard incandescent light bulbs can no longer be found for sale in most stores. This is due to the new standards for energy efficiency enforced by the U.S. government, which state that light bulbs need to consume 25% less energy. The program started unrolling in early 2012 and was completed two years later.

5 interesting incandescent light bulb facts

Incandescents may be on their way out, but their popularity and ample usage has endured for nearly a century and a half since they were invented. They’re virtually everywhere—yet how much do you actually know about them? Here’s a list of lesser-known facts about one of the most ubiquitous and humble household items:

1. Incandescent light bulbs are very inefficient in terms of energy consumption. On average, less than 5% of the energy they consume is turned into light we can actually see. The average for standard A-lamps is a staggering 2.2%.
2. Some appliances actually use the heat generated by bulbs. These include incubators, brooding boxes for chickens, and the Easy-Bake Oven toy.
3. Incandescents are taking a huge toll on U.S. energy consumption levels. You’d think that heating and cooling homes would consume more electricity, wouldn’t you? Well, you’d be wrong. According to statistics, light bulbs alone make up for 8.8% of the total levels of energy consumption—3x as much as TVs and twice as much as A/C systems and freezers.
4. Incandescents produce a whole lot of greenhouse gases. Here’s the math: if all of the U.S. switched 5 light bulbs per household to energy-efficient fixtures, it would save one trillion pounds of greenhouse gases. For reference, that equals the weight of 83 elephants!
5. Renouncing incandescent light bulbs could save a lot of money. To continue with the scenario above: if every household in the U.S. switched 5 bulbs to CFLs, the country’s consumers could save a grand total of up to $6 billion each year.

Who invented the incandescent light bulb?

Now, that’s a silly question, isn't it? It’s Thomas Edison, of course! After all, the best-known image of the famous inventor in popular culture is the one where he’s holding a light bulb. That iconic image is, indeed, real. However, this doesn’t make him the inventor of the light bulb.

Thomas Alva Edison, holding a light bulb (1925).

Image source: Encyclopedia Britannica

It is, however, true, that Thomas Edison gave the world its most efficient version of the light bulb at the time. This, in turn, became the best sold and most popular version. Why? Historians list several speculative reasons for this fact:

• Edison invented more than just the light bulb. He put together a whole integrated system of electric lighting. According to historian Thomas P. Hughes in Technology at the Turning Point, the light bulb itself wasn’t that important of an element in the whole system—but the fact that he outsmarted the other inventors by generating a system is, in itself, remarkable.
• Edison found a better incandescent material than the other inventors.
• Edison’s light bulb was efficiently vacuumed (with the aid of a Sprengel pump).
• Edison managed to put together a light bulb that had high resistance, which, in turn, made it cost efficient to distribute light through a centralized power system.

So, then, if it wasn’t Edison, who was it? The man officially credited with the world’s first light bulb to be demonstrated in public is British scientist Joseph Swan. On December 18, 1878, he first showed the masses how it works in a public demonstration held in Newcastle Upon Tyne. Swan’s first forays into developing a light bulb dated back from 1850, but he still lacked a vacuum and a consistent source of power. This was solved in 1878, when Swan first showed his lamp, equipped with a carbon rod, at the meeting of the Newcastle Chemical Society. He allegedly received the British patent for his invention in 1880. However, history tells us there are at least 22 known other inventors who worked toward developing the light bulb throughout the 19^th century. The list starts with Humphry Davy (1802) and famously continued with the holder of the Russian patent, Alexander Lodygin (1872), as well as with Germany’s Heinrich Göbel (1893), who eventually sold his patent to Edison.

What is the incandescent light bulb spectrum?

Let’s talk physics, shall we? Incandescent light bulbs produce light when the solid metal filament inside them, made of Tungsten wire, receives a surge of electricity. At that point, the filament is heated up to the very high-temperature range of 2,000 to 3,000 degrees Kelvin. This is also how incandescent light bulbs produce what is known as the blackbody spectrum. This peaks in intensity at around 1,000 to 1,500nm, i.e. close to the infrared range. We can’t actually see this peak level. However, some of this light (the yellow part) is visible to the human eye. It’s also yellow because the temperature of the blackbody spectrum is far lower than that reached by the white light of the sun (around 5,800 K). 

Image source: San Jose State University