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Light bulb technology - a basic guide

Author: Glenn Harper
Published: February 11, 2014

In the past, light bulb technology was far simpler than it is today. The only bulb-buying decision most of us made was choice of wattage, and even that was usually pre-decided by our light fitting. So there was nothing to consider.

Nowadays, things are a little more complicated as the number of types of light bulbs has increased. Several technologies now compete for our attention: incandescent, halogen, energy-saving halogen, fluorescent, and LED.

Each technology has its own particular set of advantages. The following paragraphs briefly outline them, helping you to invest in precisely the bulb(s) you need.

Incandescent

Take a look at our range of incandescent bulbsAn incandescent bulb produces light when an electric current passes through its filament, causing it to glow. Only around 10% of the energy consumed by an incandescent bulb is converted into visible light, with the rest being used to generate heat. Many previously available incandescent bulbs have been phased out by EU legislation, due to their inefficiency, but a few specialist products still remain.

Despite its failings, incandescent technology has some inherent advantages:

  • Inexpensive
  • Dimmable by default
  • Maximum CRI 100 score for reliable colour rendering
  • Amount of light (measured in lumens) remains consistent throughout lifespan
  • Instant light

Halogen / energy-saving halogen

Take a look at our range of halogen bulbsHalogen technology is a form of incandescent lighting, the main difference being that the filament is tightly enclosed by a heat-resistant quartz or hard glass envelope. Inside this envelope is a halogen gas, whose purpose is mainly to return evaporated tungsten onto the filament, thus extending the lifespan of the bulb. It does this through a chemically reactive process known as ‘the halogen cycle’.

Energy-saving halogen bulbs use either an IR reflective coating or a less conductive premium-fill gas (i.e. krypton or xenon) to reduce heat loss and increase efficiency.

Halogen advantages include:

  • Inexpensive
  • Very crisp, bright-looking light (especially low voltage)
  • Dimmable by default
  • Maximum CRI 100 score for colour rendering, with slightly less red bias than original incandescent bulbs (i.e. better balanced for colour-critical applications)
  • Amount of light (in lumens) remains consistent throughout lifespan
  • Double the lifespan of original incandescent bulbs
  • Available in ‘capsule’ form for use in space-confined applications
  • Energy-saving versions use 20-30% fewer watts than original incandescent or regular halogen technology
  • Instant light

Fluorescent

Take a look at our range of CFL BulbsFluorescent lighting comes in tube or CFL form. The latter (Compact Fluorescent Lamp) includes spirals, sticks, 2D, Biax, and retrofit low-energy bulbs. Regardless of shape, fluorescent lighting works by exciting mercury atoms with an electric current. In turn, this produces a UV light that stimulates the interior phosphor coating, causing it to fluoresce and emit visible light.

Fluorescent light sources require a ‘ballast’ to regulate current and deliver sufficient voltage to start the lamp. Most CFLs include this in their base, allowing use as direct replacements for regular bulbs. Fluorescent tubes and some lamps require an external ballast, which is usually integral to the light fitting.

Perhaps the greatest disadvantage in fluorescent lighting is a generally inferior dimming capability (often non-existent), but there are various advantages:

  • Inexpensive by comparison to LED
  • High energy efficiency—typically 70-80% more efficient than incandescent or halogen
  • Very long lifespan compared to filament bulbs, reducing maintenance costs
  • Strong omnidirectional diffuse light that is especially useful as a main light source
  • Broad choice of colour temperatures
  • Low running temperature

LED

Take a look at our range of LED BulbsThe LED, or Light Emitting Diode, has been intensely developed in recent years to become one of the greatest clean technologies of the early 21st century. LEDs can produce a white light in a couple of ways, either by blending red, green and blue primary colours, or by use of a blue LED and yellow phosphor. The latter is a cheaper and easier way of producing bright white LEDs, and is behind most LED design.

Most modern LED bulbs use High Power LEDs, which can be surface-mounted to produce a bright omnidirectional light. A second type of LED is the COB (Chip-on-Board), which consists of LED chips packaged extremely densely into a single LED module. Allowing a fantastically smooth and intense light, COB LEDs are often used to closely replicate halogen spotlights.

LED bulbs generally require a greater initial investment than other technologies, but the expense is always likely to be recovered, and usually within a few months in commercial environments. Here are some of the numerous advantages:

  • Exceptional energy efficiency, usually superior to fluorescent and converting about 80% of used energy to light
  • Long lifespan that greatly reduces maintenance costs (up to 50,000 hours)
  • Negligible IR or UV radiation reduces degradation when lighting sensitive items (e.g. artworks, food)
  • Shock and vibration resistant (solid-state form of lighting)
  • Reliable cold-temperature performance
  • Extremely compact for design flexibility
  • Broad choice of colour temperatures
  • Very good dimming performance with compliant drivers and switches. Colour remains constant even when dimmed to low levels.
  • Directional form of light with very little spilled light outside of its specified beam
  • Unaffected by frequent switching
  • Instant light

Feel free to browse our full range of light bulbs.

Looking for inspiration or more information? Try our Lighting Advice section.


This article was tagged with Light bulbs, Lighting Technology