Features of energy efficient bulbs

The packaging for energy efficient bulbs has lots of useful information on it to help you choose the right light for you.


Like standard incandescent light bulbs, you'll need to make sure the base of the new bulb (bayonet or screw fitting) is the same as the one you're replacing. If it doesn't fit, don't force it.


You may also see lumens (lm) on packaging, to indicate brightness. While wattage measures the energy a light bulb uses, light output is actually measured in lumens - the higher the lumens, the brighter the light. Both will appear on most light bulb packaging, which can be helpful when you want to find which bulb uses the least energy for the most light output. So think lumens for brightness not watts (W). 

Energy efficient bulbs produce more light with less energy than standard incandescent bulbs, so if you're replacing a 100 W incandescent bulb, you'll only need to use a 20 to 24 W CFL or 15 to 18 W LED.

Check the packaging of the efficient bulb to find the correct wattage and lumens.

Standard incandescent bulbEquivalent new generation halogenEquivalent CFLEquivalent LED

40 W 

(415 lumens)

28 W 12 W 6-9 W

60 W 

(710 lumens)

 42 W  15 W  9-12 W

75 W

(920 lumens)

 52 W  18/20 W  12-15 W

100 W

(1300 lumens)

 70 W 20/24 W   15-18 W


Light bulbs come in a variety of colour temperatures, which are measured in kelvins (K). The higher the K, the cooler the light. ‘Warm white' is roughly the same colour as standard incandescent light bulbs.

  • Warm white (2,700 K to 3,000 K)
    Helps enrich the warm colours in your home, and is suitable for lounges, hallways and bedrooms.
  • Cool white (4,000 K)
    Gives off a bluer light that improves contrasts, so ideal for laundries and bathrooms.

Special features

Light fittings with special features or functions (like dimmable lights, bathroom fan lights and chandeliers) need compatible light bulbs. Check light bulb packaging to find ones with the functionality you need.