How much energy is conserved by switching to CFLs?

Regular bulbs, also called incandescent bulbs, glow when a tiny coil of wire is heated by electricity.  Energy-saving light bulbs, usually called compact flourescent bulbs or CFLs, produce light when electricity runs through mercury and gases inside of a spiral-shaped bulb.  For comparison sake, the cost for one regular 75 watt bulb is about 50 cents, and each bulb produces 1,200 lumens, while a CFL that also produces 1,200 lumens costs as little as $2.53.

So why would you pay approximately 5 times more for a CFL bulb?  Well the cost of energy used to light a regular bulb for 4 hours per day, in one year is $9.30, and the cost for the same time period and usage for a CFL is $2.50, a difference of $6.80 for just one light bulb.  Additionally, the regular bulb uses 75 watts of energy, while the CFL uses a mere 20 watts of energy, yet they both produce the same amount of light!  Another major benefit of the CFL is that it produces10,000 hours of light, while a regular bulb produces only 1,000 hour of light.

So back to the original question...

How much energy is conserved by switching to CFLs (comparing 75 watt regular bulb which is equivalent to a 20 watt CFL bulb, each producing 1,200 lumens of light)?  55 watts of energy are conserved by using a CFL bulb. 

If you replace one regular 75 watt bulb with a 20 watt CFL bulb, how much money is saved on energy costs in a year? $6.80 per year in energy savings per light bulb will be realized by making the switch.

How many regular bulbs would it take to light a lamp for the same amount of hours as one CFL bulb?  It would take 10 regular bulbs, at  50 cents a piece, or $5.00 for 10 regular bulbs, and the one CFL bulb that produces the same amount of hours, can be found for as low as $2.53-$4.00 per bulb.

Why do regular lightbulbs use so much energy as compared to CFLs?  Regular bulbs are making light and heat, and the heat is wasted. 

So what are the pros and cons of regular bulbs vs. CFLs?
One disadvantage of CFLs is that they take time to warm up to full brightness, and regular bulbs are at full brightness within a second, and only some CFLs are labeled for dimming control..  Another issue is that CFLs contain small amounts of mercury as vapor inside each bulb.  However, the retail price of the CFL includes an amount to pay for recycling, and manufacturers and importers have an obligation to collect and recycle CFLs.  The Home Depot stepped up and became the first retailer to make CFL recycling options widely available at it's stores, and collection bins are easily accessible.  Many other retailers also provide recycle centers for CFLs.  According to Wikipedia, the first step of processing CFLs involves crushing the bulbs in a machine that uses negative pressure ventilation and a mercury-absorbing filter to contain mercury vapor. The crushed glass and metal is stored in drums, ready for shipping to recycling factories.  Conversely, regular light bulbs can not be recycled.

On the bright side :) 
CFLs can be recycled.  The mercury inside the bulbs can be recovered and kept out of landfills.  Using CFLs results in energy savings of $6.80 per bulb.  CFLs last 9,000 hours longer than regular bulbs.  CFLs save 55 watts of energy.

So here's to a brighter future with energy savings and lower electric bills with CFLs :)  


Sources:  http://en.wikipedia.org/wiki/Compact_fluorescent_lamp, November 18, 2010.