Economic sense: It shows on your electricity bill when you change Incandescent light bulbs to either to CFL. In the US market the cheapest CFL can be bought for as low as 92 cents in Wal-Mart but the first question that comes in your mind is in how much time is the payback. Calculating the Payback lies in knowing how much time do you turn the lights on, does the local utility have a rebate program, is the rebate available to energy star light bulbs only (in which case the cost might be a little higher), cost of electricity, labor costs and shipping costs incurred.
For example, let us say in your house you want to change the light bulb in your bathroom. So first you need to think how many hours do you turn the light on in the bathroom, I will say around two hours for a family of four. So you typically use the light for 700 hrs a year. So depending on the energy costs in your area the payback will be around 1.2 years. But in case you are changing the light in your hall and say you turn the light for 6hrs a day then the pay back will be fast approximately in 146 days. And if you have the light turned on 24hrs a day the pay back is in 36 days. So it always makes economic sense to change to CFL’s depending on usage and cost of electricity. If you have a rebate program in your uility the payback might be faster. If you know your local utility costs and want an exact payback time for your situation leave a comment
I will write about the environmental sense in my next post
*All the calculations are based on the electricity rates in Montana which are energy rate is at 0.06 /kWh and demand rate is 9.01/kW-month.
