Buyer's Guide
Colour Temperature
The colour output of an LED bulb is measure in Kelvins. 2700k-3000k is known as Warm White, and most similar to traditional halogen bulbs. 4000k-5000k is considered Cool White, and often used in bathrooms. 6000K+ is daylight and is the brightest colour, often used in commercial applications.
Lumens (Brightness)
The brightness of an LED bulb is measured in Lumens. A typical LED Spotlight equivalent to a 50 watt halogen will emit between 350 and 400 lumens. Cool White bulbs produce approximately 5% more lumens than the soft warm white option. The greater the lumen output the brighter the bulb. Many efficient LEDs are now producing 100 lumens per watt. For comparison, traditional halogen bulbs only manage between 7-8 lumens per watt of electricity.
Beam Angle
The beam angle of a bulb refers to the angle of usable light emitted from a bulb. For ceiling spotlights (GU10s) a beam angle of 35-40 degrees is ideal as this is most similar to traditional halogens. Any wider angle than 60 degrees and you will find that the bright light catches your eye easily which is uncomfortable. LED bulbs such as candles and standard GLS globes bulbs are better suited to a wider beam angle, particularly if using the bulbs in lamps, so as not to have dark spots beneath the lamp. A beam angle of 300 degrees is ideal for floor and desk lamps, for ceiling and pendant lights 240 degrees will be adequate.
Dimmer Compatibility
Dimmable LED bulbs should be used with LED Trailing Edge dimmer switches. This will secure the longevity of the LED bulb and produce the greatest dimming range. The Varilight V-Pro range of dimmer switches are best suited to LED bulbs. The full range of Varilight's LED dimmer switches are available from Everything-LED.
Low Voltage vs Mains voltage Lighting
MR16 (otherwise known as GU5.3) MR11 and G4 are low voltage lights and are powered from a transformer. If changing these bulbs to LED, you will also need to change the transformer that powers the bulb to an LED version. All other bulbs are mains voltage and the LED equivalents are a direct replacement.
New Energy Efficiency Requirements
It's worth bearing in mind that products that have a lower rating on their new label have not become less efficient - they are consuming the same amount of power as they always have. A clear example of this is the Integral LED High Performance + Panel which has an industry leading efficiency of 175lm/w, but is still only classified C on the new scale.
