Lightbulb Guide

Options to save money and do good!

One of the first actions on our Sustainability Checklists is to replace some of your old-fashioned incandescent light-bulbs.  There are a number of very good options that will save you money over the medium and long term, and reduce emissions significantly.

Any major home goods store will have a good range – and will be able to advise you on what bulbs to choose.

To learn more about the LED vs CFL and Incandescent bulbs discussion, read here or read on below.

We would love to hear your ideas, or feedback, so please contact us at


Types of light bulbs: Incandescent, Fluorescent, High Intensity Discharge (HID), Compact Fluorescent Lamp (CFL), Light Emitting Diode (LED)

Watt: Amount of energy consumed.

Lumen: Amount of light output (a 60 incandescent light bulb produces 800 lumens of light) brightness.

Kelvin scale: The color temperature in degrees: 2700 soft white, 3000-3500 bright white, 4000 daylight, 5000-6000 cool white.



Thomas Edison invented the incandescent household lightbulb in 1879.  This is a metal filament (thin wire) in a vacuum-sealed glass container. Usually 60-100 watts, with a yellow hue.

  • Pros: better than gas lamps, inexpensive to buy.
  • Cons: short life, run very hot, expensive to run


Next were the fluorescent light bulbs. A gas-filled tube with 40 watts per tube and usually 2 or 4 in a fixture, with a blue hue.

  • Pros: long life, many different color temperatures,
  • Cons: need a special fixture, moderately expensive, the gas contained inside is toxic and harmful if glass is broken

High Intensity Discharge

HID lamps are mercury vapor, high pressure sodium metal halide used for street and parking lot illumination.  Around 1,000 watts

  • Pros: high lumen per watt ratio, very long life
  • Cons: very  expensive, need a special fixture

Compact Fluorescent Light

CFLs are the famous swirly bulb – a gas-filled spiral. Uses 13 watts to be equal to a 60 watt incandescent bulb.

  • Pros: uses 80% less electricity than an incandescent lamp, runs warm to the touch, long life
  • Cons moderately expensive, the gas contained inside is toxic and harmful if glass in broken, needs to warm up for full brightness

Light Emitting Diode

LEDs are even lower energy-use than a CFL and many colors available, from infra-red to ultra-violet.

  • Pros: Uses about 9 watts equal to a 60 watt incandescent lamp, cold to the touch, last 15+ years of normal use, instant-on.
  • Cons: expensive up front cost


Many energy-saving options are available when think of the cost of *owning* the bulb, not just buying it.  There is more help on this below!  And look at the brightness (lumens) output not the wattage.

What do they cost?

Well the newest ones are free!  Sort of.  They cost you more to put in, but they will save you that money and a lot more.

LIghtbulb table 1


Estimated lamp life based on 6 hours per day 365 days per year.
Does NOT include the cost of electricity.

LIghtbulb table 2

Cost of electricity = 14c per kilowatt-hour (kWh).

…so the more expensive bulb to buy – the LED is the cheapest overall.  In fact by the end of the first year the old-style incandescents have cost you $19 and the LED has cost you only $7.75!