Does CFL really save money for the customers

There is a myth that CFL saves lots of money to the customers.

Lets see if this is always correct or under what conditions/usage CFL really saves money and what needs to be considered before purchasing a CFL.

On an average especially in the city, maximum usage of a light-bulb will be in the hall, where generally use tube light. A tube-light approximately 40 W per hour. (you also get lower-wattage light-bulbs).

If a person intends to replace this light bulb with CFL he might use a CFL bulb in the range 15W to 20W though its not equally bright as a tube-light which has higher lumen.

So lets assume a person uses 20W CFL as a replacement for a 40 W tubelight.

The savings he obtains by using 20W CFL instead of a tubelight is 20 W per hour.

Now lets calculate the extra cost incurred to buy the CFL over a tube-light.

Cost of a branded CFL starts from Rs 130 and goes till Rs. 250. Average cost = Rs 175.

The cost of bulb(incandescent) is around Rs 15.

Cost of tube light is around Rs 40.

Extra cost of a CFL equals 175 – 40 = Rs 135.

A unit of electricity refers to 1 KWh or 1000Wh.

To save one unit of electricity you need to use the CFL for 50 hours.

Lets assume a unit of electricy on an average costs Rs 2.5. This varies from city to city, state to state.

Lets calculate the total number of hours a CFL needs to be used, to recover the extra cost incurred in buying a CFL, assuming above values for the cost of CFL, unit of electricty.

Number of units = 135/2.5 = 270/5 = 54 units

34 units translates to usage of 54* 50 hours of CFL, ie. 2700

This means one needs to use a CFL for atleast 2700 hours to recover the initial high cost incurred in buying a CFL.

Lets calculate approximately how many days this would translate to.

Assuming that on an average the light bulb is used for 5 hours daily,

Total number of days = 2700/5 = 540 days.

This means that a CFL needs to be used every day for 5 hours for atleast (apprx) 1.5 years or 18 months to recover the extra cost incurred on a CFL.

But the problem being faced is that a CFL if used in low-voltage areas or voltage-fluctuation areas, it goes bad. The warranty of CFL is nowadays getting limited to 6 months (Areva/Orpat) is one such case.

The CFL technology is not yet mature in terms of the life of CFL.
We have been using CFL for almost 10 years now and on an average lifetime of CFL over 10 year period has been 6 months for me. But technology has improved a little providing better life time, but still not to desired levels. The life is not as good as a tube-light or an incandescent bulb.

So things you need to consider before making decision to buy CFL:

1. Do you have voltage fluctuations or low-voltage problems in your house?
2. How long do you use light bulb you are planning to change with CFL per day?
3. Cost of unit of electricity at your place.
4. Cost of CFL you are planning to buy.
5. The warranty period of CFL you are planning to buy

Incase you have decided to buy CFL, make sure that the date of purchase is written on CFL and also the shop name/initials are mentioned on CFL itself (not bill). This helps in getting a replacement when the CFL goes bad.

I have got replacement couple of times and the date of purchase and shop initials mentioned on CFL proved to be very handy.