Basics of Modern Light Bulbs

The technology of the seemingly simple light bulb has changed in major ways since it’s inception, and since the move past the halogen technology, it has been more difficult to follow what is still considered energy efficient AND meets the requirements of your house.

First I will describe the technology and some of the technical details, and end with an explanation of the practical elements of the light bulb, the fitting and the shape.

Technology

There have been four prevalent light bulb technologies since Sir Thomas Edison‘s and Sir Joseph Swan‘s incandescent light bulbs, in order of development: the Halogen light bulbs; The Compact Fluorescent Lights (CFL) bulbs; and the modern Light Emitting Diode (LED) light bulbs, also known as Solid State Lighting (SSL). At each iteration the energy usage has decreased significantly. Although the Halogen lighting was a large step forward, it’s long heating up time had it falling out of favour.

Modern LED light bulbs avoid this and light up immediately with a sharp light and also use the least amount of energy. LED lights are also safer, as older light bulbs heat up gasses to produce light, so breaking the bulb could expose you to dangerous Mercury gasses. LED lights use no gasses; the glass casing protects the diode inside, so puncturing the glass has no effect.

Luminaire recommends using only LED lights, as they are safer and their cheaper running costs save you the difference in costs between LED bulbs against any incandescent or halogen lamp in a matter of months.

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Comparative Watt usage between light bulbs

Lumens

The amount of light emitted is measured in lumens. Different lighting technologies emit different amounts of lumens per Watt, as seen in the figure above. LED lights far outcompete the older technologies, and run up to 33% more efficiently than CFL light bulbs.  The amount of lumens required for a room varies, and the home-owner might also have specific requirements. To the right is a graph detailing recommendations for lumens per square meter in different rooms.

Colour Temperature

The colour of the bulb is determined by the temperature of the diode, measured in the Kelvin temperature scale. Warmer temperatures are fit for relaxed settings, such as living rooms and bedrooms, while cooler whites show the room in far more detail, making it more suited for tasks.

Temperature/Colour

1000k / Very Warm

2700k / Warm

3000k / Warm White

4000k / White

5000k / Cool White

6000k / Daylight

Area Lumens/Sq M
Kitchen 300-400
Kitchen (Task) 700-800
Living Room 400-500
Hallway 300
Bedroom 300-400
Bedroom (Task) 700-800
Bathroom 500-600
Bathroom (Task) 700-800
Reading Area 400

Recommended Lumens/square inch

Fitting and Shape

In practical use, the two most important factors for a light bulb are it’s fitting and shape. The fitting must fit the socket in the home and the shape must fit the requirements of the home owner, no matter what room or function it is for.

Fitting

The fitting is the connector between the bulb and the mains. There are over 70 unique fittings for light bulbs for different uses for domestic, retail, industrial or other uses. The most common fittings in the home are the E27, E14, and B22. E27 is the conventional Screw Cap that Sir Thomas Edison developed and it still sees wide use and comes in most shapes, as does it’s Bayonet Cap equivalent B22. The Small Edison Screw, E14, is used for decorative lighting, such as lamps and some chandeliers and commonly comes in mini-globes or candles. It also has a bayonet form, the B15.

Shape

Different shapes of bulbs exist to shine light onto surfaces in different ways. The Standard shape developed back in Thomas Edison’s days, it’s the most popular shape for bulbs offering an even spread of light. These also come in other shapes, the smaller Golf Ball, and larger Globe. Spotlight are used to shine lights in specific directions or on specific objects. For example, inside cupboards, under cabinets, in lamps on the ceiling, or in showcases. Candles, shaped like a flame, are decorative shapes for chandeliers and lamps.

Aigostar E27 Standard Light Bulb

Bright Goods B22 Globe

Aigostar E14 Candle

Lumilife B15 Golf Ball