Eco-Bulb Learning Center
Lumens
The amount of light generated by a lamp is measured in lumens. Carbonberry states the total lumen output for every bulb we sell. Most manufacturers state the lumen output on the packaging along with the life expectancy and the watts consumed. In order to figure out how efficient a bulb really is, the lighting industry divides the total lumen output by the watts consumed. This is stated in "lumens per watt" (or "luminous efficacy"
by lighting guru's). The chart above gives you a broad view of the efficiencies of various bulb types. As you can see, the incandescent bulb consumes a lot more power to generate the same amount of light as a regular CFL. LED's are starting to be a viable replacement for CFL's and the industry expects LED's to surpass CFL efficiencies over the next few years.
Note: If you're an LED bargian hunter, always ask how many lumens are output by the bulb. Many vendors talk "watts" and try and stay away from lumen conversations. So if someone is selling you an 8 watt LED that outputs 100 lumens of light (12.5 Lumens per watt), you're really buying an expensive LED that is equivalent to a trusty old incandescent bulb. If the vendor doesn't know what a lumen is, its time to walk away!
Heh! Where did that lumen go?
All bulbs (incandescents included) generate less light over time. By the time the bulb is "burnt out" , 20-30% of its intial luminosity has been lost. No worries, this is a slow and gradual process and most people don't even notice. LED's are a little different because the diode part usually doesn't fail , it just gets dimmer over time. So you're probably wondering ... How is life expectancy measured if they (LED's) rarely "burn out"? Well ,the new energy star standard states that
an LED is considered "burnt out" when it has lost 30% of its luminosity. Having said that, LED bulbs (called luminaries) are much more than a collection of diodes soldered on a board. They contain complex circuitry, fan heat sinks and other parts that could fail as well. So its important to buy quality LED's in order to acheive the desired savings.