It seems like a surprising claim, but simply switching your regular lightbulbs for CFLs, even though they have a higher initial cost per bulb, can easily save you $100 a year. Let’s look at them in detail.
I took the information off of GE Soft White A19 bulbs in both their regular and CFL form and wrote down some basic information. The bulbs are nearly identical when in the socket (very very close in initial lumens), so what we’re interested in is the cost, the wattage, and the life of the bulb.
GE Soft White A19 (regular)
840 initial lumens
$2.99 a four pack (at Target)
$0.75 per bulb
GE Soft White A19 (CFL)
825 initial lumens
$18.73 a ten pack (at Lowe’s)
$1.87 per bulb
Let’s start out with the bad news. Let’s say your residence has 15 light sockets. To fill each light socket with a non-CFL bulb, you’ll spend $11.25, but to fill each light socket with a CFL bulb, you’ll spend $28.07. This means that the cost of converting all the bulbs in your home from regular to CFL is about $16.82.
Now we turn to the many financial benefits of CFLs. Over 10,000 hours of use, you’ll use 15 CFL bulbs (on average), but you’ll use 150 non CFL bulbs (they’re rated for 1000 hours of use, so you’ll blow ten of them on average over 10,000 hours). So, with the CFLs, you’ll spend that same $28.07, but with regular bulbs, you’ll spend $112.50, a savings of $84.43. The average bulb is on for four hours a day, so you’ll need several years to see this savings, but if you figure it down to the month, you’ll save about a dollar a month on the bulbs alone, or about twelve dollars a year.
Given the information on the bulbs themselves, a non-CFL bulb uses 60 watts, while a CFL bulb uses only 15 watts. Converted to kilowatts, that’s 0.06 kilowatts for the non-CFL bulb and 0.015 kilowatts for the CFL bulb. For calculation’s sake, I pay about $0.08 per kilowatt hour for our electricity (on average), and we have all of our bulbs on an average of four hours a day.
Let’s see how much we save in a day in our home with fifteen bulbs. We use fifteen bulbs for four hours each, so that means we use 60 hours worth of bulbs each day. The non-CFL bulbs use 0.06 kilowatts, so we multiply 60 hours by 0.06 kilowatts to get 3.6 kWh for the normal bulbs. The CFL bulbs, though, use 0.015 kilowatts, so we multiply 60 hours by 0.015 kilowatts to get 0.9 kWh.
So, each day, the savings in kWh usage by using CFL bulbs in our example is 2.7 kWh. If we pay $0.08 per kWh, simply by having the CFLs in our light sockets, we save about $0.22. Every day. Automatically, without thinking about it a bit.
Over a month, the CFL savings is a dollar (the savings you make because CFLs are durable) 30 days at $0.22 a day (the savings each day because of less energy use), which comes out to be about $7.50 a month. And the best part is that because CFLs last so long, you’ll spend a lot less time changing bulbs!