A Closer Look At CFLs, Part 3: Lumens And Kelvins And Watts, Oh My!

Posted on August 25, 2007 by Melissa 
Filed Under A Closer Look, Frugality

After examining the good and the bad with CFLs we are now faced with how to determine which CFLs you need by deciphering the watts, lumens, and kelvins. No worries! Let’s look at how to pick the right CFL for any occasion.

Remember that quality counts. Unfortunately, I have found not all CFLs are created equal. Some “bargain” CFLs may flicker and buzz due to inferior quality. I have had good luck with GE, Philips, Home Depot, and Sylvania CFLs so far. We recently tried an off-brand from a grocery store and found that they flickered. Although they were cheaper we weren’t thrilled with the added strobe light effect. Even if you save a few bucks initially it isn’t a good deal if you have to replace them due to annoying flickering like I had to.

If you still prefer to buy off-brand (which is perfectly fine – I’m sure there are many quality off brand CFLs out there) you can feel pretty confident in its quality if it has an energy star logo on it. Also, keep an eye out for coupons and specials to help lower costs. Check with your local electricity company too. You never know if they are offering a free CFL (as they did for us).

Decode the wattage and lumens. The wattage is the electric power required by a device. If you have a 60 watt incandescent light bulb it requires up to 60 watts for operation. The lower the wattage, the lower the amount of energy is needed for it to run.

Lumens are basically a unit of measurement for the amount of brightness a light source can produce. The higher the lumen rating, the higher the light output or brightness of that bulb. By looking at lumens we can determine how to get the same brightness that we got from a 60 watt incandescent from a lower wattage CFL.

I have noticed that there is some variation between manufacturers on what CFL is equivalent to what incandescent. To be sure you are getting what you need please check the box itself to see what kind wattage bulb the CFL is equivalent to. Here is an example from Energy Star.

CFL Comparison Chart from Energy Star

For example:

You are looking to change out a 60 watt incandescent bulb and like the level of light it provides. According to this chart, that bulb is producing a minimum of 800 lumens. To match that same brightness you will need to get a 13-15 watt CFL to replace that bulb.

You might want to go with the middle or higher wattage on the equivalent CFL wattage range, as some people feel the light can be a bit “stingy” from the lower wattages even though the lumens are the same. It’s all a matter of preference.

One thing you can do with CFLs is adjust the brightness of a room without having to change out fixtures. If a fixture is rated to only take up to 75 watts but you feel the area is still too dark with a 75 watt incandescent bulb, you can go much brighter by going with a higher lumen rated CFL. Instead of having a ceiling of just 1,100 lumens like you have with a regular bulb, you can increase the brightness all the way to 2,600 lumens with a CFL and still stay safely within the maximum wattage allowed for that fixture.

Choose the color with kelvin. Color temperature can be measured. The higher the number in kelvins, the cooler or more blue the light appears. For those sensitive to the way light appears or those looking for a specific lighting effect, this rating will be critical in finding the right CFL for you. Light color is often a make or break issue when people move to CFLs.
CFL Color Comparison - Picture taken by Quintote for Wikipedia - CC licensed - http://en.wikipedia.org/wiki/Image:CFBulbs.jpg

The majority of CFLs today offer a warm or “soft white” light (2700–2900K), comparable to incandescent bulbs. This is what most people prefer in their homes as it is warmer and considered inviting.

However, if you prefer a cooler or bluer light, look for CFLs with a rating of 4000K and above. They will often be labeled as “Cool White”, “Daytime”, or “Natural”. This lighting can be good for task areas and enhances cooler colors like blues, greens, and purples.

To determine the color you are getting when looking at a particular CFL you can follow this scale from Wikipedia as a guideline.

Color Temperature Kelvin
“Warm White” or “Soft White” < 2700 K
“White”, “Bright White”, or “Medium White” 2900 – 3000 K
“Cool White” 4000 K
“Daylight” (varies w/ manuf.) > 5000 K

Now we should be equipped with the tools to choose the CFLs we want. How can we use them in a way as to maximum their life and cost saving benefits? Tune in tomorrow for the conclusion of our series.

A Closer Look at CFLs Series Index
    Part 1: Conscientiously Frugal Lighting
    Part 2: Every Rose has its Thorn
    Part 3: Lumens and Kelvins and Watts, Oh My!
    Part 4: Take it to the Limit


2 Responses to “A Closer Look At CFLs, Part 3: Lumens And Kelvins And Watts, Oh My!”

  1. Engr.Helal Uddin(new comment) on November 27th, 2008 7:46 am

    wanto to know about CFL Circuit

  2. Engr.Helal Uddin(new comment) on November 27th, 2008 7:47 am

    want to know about cfl circuit


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