Appendix A – Lumens, Watt Equivalents, Bulb Life & Color

14_05_14 Label SMWhen shopping for bulbs make sure to find this label on the box (see label to the right).  This label will tell you everything you need to know about the bulb.  The following four features will help you choose the right bulb.

  1. Brightness (in lumens) – This is a good indication of how much visible light you will get from the bulb.  Generally speaking, the bigger the number, the more light.
  2. Life of the bulb – Initial price is one thing, replacement frequency or life can change your math.  LED’s can last decades, CFL’s from five to seven years and incandescent lights one to two years.
  3. Light Appearance (color temperature) – Lights range from warm to cool and most Home Depots have a helpful display setup where you can see the whole spectrum of light bulb temperatures.  Warm tends to be a more inviting natural light and cool lights tend to have a more harsh industrial feeling.  All the lights tested in this article are classified as cool.  I encourage you to visit a Home Depot to check them out before making an investment.
  4. Energy Used – This is an indication of the actual energy the bulb is going to use and is measured in watts.  For instance, a 65w incandescent bulb uses 65w but the LED shown here is a 65w “equivalent” and uses only 12.5w.  This makes a big difference when you receive your electricity bill.

Appendix B – Light (lumen) Output Over Time & My Thoughts

I uncovered two interesting facts during this test.  The graphs provide a good visual illustration.

Light Degradation Data – I was very surprised to see how much light degradation occurred over the ten minute test.  Take a look at the Lumen Output Over Time graph below.  The CFL saw dramatic light output degradation that occurred steadily over the ten minutes.  It is worth noting that the amp draw also dropped indicating that the efficiency ratio was remaining constant.  Although I have no evidence to support it, my suspicion is that the CFL bulb’s performance dropped faster than the bulb with integrated trim because the CFL bulbs cannot expel heat fast enough.

Cree Bulb, Small Bulb with a BIG PUNCH – I am impressed with the amount of punch that the Cree LED light bulb packed.  I was expecting the Cree bulb to under perform the bulb with integrated trim due to the larger heat sync on the later.  Compare the two graphs.  The Cree bulb was the lowest energy user and the best light generator.

Amp Draw Over Time

Amp Draw Over Time

Lumen Output Over Time

Lumen Output Over Time