10 Lighting Terms You Really Should Know
Let's face it, buying a light bulb isn't as easy as it used to be. There are so many different types that knowing which to choose is a task in itself, but factor in all the jargon and it becomes nigh on impossible!
So here's a list of 10 common lighting terms and their definitions, to help get you started.
1. Lumen Rating
Contrary to popular belief, light intensity isn’t measured in watts, it’s measured in lumens and, the greater the number of lumens, the brighter the light bulb.
When you’re buying a light bulb, always go for the one with the highest number of lumens for the fewest watts. With regard to this magical ratio, you simply cannot go wrong with LED light bulbs such as the best-selling GU10 LED Bulb 80 SMD, as it produces 400 lumens for just 3.3W of power. It’s the lighting equivalent of a 50W traditional bulb, requiring just a fraction of the electricity to power it.
2. Luminous Efficacy
Luminous efficacy refers to the amount of light produced by each, individual watt of energy used to run a bulb. It’s expressed as a ratio (lm/w), which is calculated by dividing a bulb's lumen-rating by its wattage. LED Light bulbs have a very high luminous efficacy, while other types of lighting, such as halogen/incandescent, have a low luminous efficacy.
Many people are familiar with the term, but surprisingly few know what it actually means. The number of watts refers to power consumption and the rate at which energy is drawn from an electrical system.
Light bulbs with a high wattage use more electricity and cost more to run. As stated previously, LED lights have a very low wattage making them very cost-effective.
An example of a light bulb that has a relatively high wattage in comparison to its light output is the 60W incandescent. If an electricity charge of 13.75 pence per kWh is assumed, and it’s switched on for 8 hours a day for 365 days, this bulb will use up 175.20 Kilowatt hours and cost £24.09.
Compare this to the equally bright MR16 LED Spotlight 27 SMD, which requires just 6W of power. This LED bulb will use just 17.42 kWhs and it’ll cost only 2.41 to run for a year!
The best way to think of volts is as a measurement of electrical potential. Volts push the electrical current through a conductor. Most household bulbs, such as GU10 LEDs, operate at 240V, also known as mains-voltage, but low-voltage bulbs, such as MR16 LEDs are becoming increasingly popular.
5. Beam Angle
This is the angle at which a bulb emits light. Beam angles are measured in degrees, but it is also common for them to have specific designations, such as wide flood or narrow spot.
Bulbs with a relatively narrow beam angle of 45° or less will produce a concentrated spot of light, while bulbs with a wide beam angle, that’s in excess of 60° will flood an area with light, hence the names spotlight and floodlight.
6. Colour Temperature
Colour temperature refers to the colour of the light produced by a bulb and is measured in degrees Kelvin (K). A simple rule-of-thumb by which to remember colour temperatures is this: the lower the temperature, the mellower the light; the higher the temperature, the brighter, more penetrative the light.
LED lights come in a choice of three colour temperatures, each of which will enable you to tailor the ambience of your room to better reflect its function and purpose:
- Warm White (3000K) has become the go-to choice for residential illumination, with a great many preferring its mellowness and similarity to traditional incandescent light. Typically used for general illumination in living spaces around the home, its soft toned light helps to promote a relaxed and comfortable ambience.
- Cool White (6000K) is used in locations such as the kitchen, where a brighter light source is required, and can serve both functional and aesthetic purposes. It can imbue a space with a very modern feel or enhance the appearance of existing décor, particularly where a primary colour palette has been used.
- Daylight White (4000K) is the closest simulation of naturalistic sunlight that’s available in terms of LED lighting. Historically popular for use in studies and offices, it’s now being used more frequently in many other areas of the home.
The CRI, or colour-rendering index, is a measurement of the quality of an artificial light source, and denotes its similarity to daylight. Objects and colours viewed under a bulb with a high CRI of 80 or more will appear vibrant and natural, whereas those viewed under a bulb with a CRI of less than 79 will appear washed out and may even change hue.
A Luminaire is a light fixture that includes the bulb. Luminaires are different from ordinary fittings in that they come all-in-one, as a complete unit and don't require a separate bulb. Generally speaking, they have a high light output and last longer than traditional light bulbs.
Fitted LED downlights are good examples of luminaires, and there’s a huge variety of them to choose from.
The fitting is the part of the bulb that connects it to the electricity supply. There are many types of light bulb fitting, but all are designed to allow for easy removal and replacement of old light bulbs. Fittings can be identified by a unique code, usually consisting of letters and numbers. A large Edison screw, for example, is called an E27 fitting.
10. Life Hours
The Life hours of a light bulb are the number of hours it’s expected to last. For most light bulbs, the life hours are calculated by observing the point at which 50% of a group of sample bulbs begin to fail.
The life hours of LED light bulbs are calculated by their lumen maintenance, meaning the amount of light retained by a light source over a given length of time.
Thus, the lighting efficacy of the vast majority of LED bulbs has been estimated at 50,000 hours which, in comparison with that of an incandescent bulb’s 1200 to 2000 hours is absolutely phenomenal, equating to over 17 years!
Don't forget to check out our glossary as well, where you’ll find many more lighting terms explained.
Were there any we missed? If so, and you’d like us to include a few more, please let us know in the comments below.