If you've ever stood in a store aisle and pondered which light bulbs would give you that ideal combination of low price and long life -- something you need to consider if your budget is rather tight -- you may have just gone with whatever had the longest reported lifespan. If that's the case, you need to read a little more. Many of those lifespans are based on rather short usage times. Unless you calculate how much you really use the bulbs (at least a ballpark figure), you could inadvertently end up spending more on replacement bulbs than you intended.
When Advertised Lifespan Is Helpful
If you're trying to compare different types of bulbs -- incandescent vs fluorescent vs. LED, for example -- then the advertised lifespan is helpful even if it's based on usage that is unrealistic for you. All you're doing in this case is seeing how much more life you could get out of a different type of bulb.
When Usage Comes Into Play
It's when you're comparing the same basic type of bulb between brands or between models that the amount of usage becomes important. Those models and brands differ in price. You might think it's sensible for a bulb with a longer lifespan to have a higher price than a bulb with a shorter lifespan -- but not if the higher lifespan is based on a shorter amount of daily usage.
And usage does affect lifespan. Energy Star's online calculator for compact fluorescent bulbs shows that a 23-watt replacement CFL bulb would last for 8.2 years if used for only two hours per day. But if you up the usage to six hours per day, the lifespan shrinks to only 2.7 years.
As a hypothetical example, Bulb A costs $1 and has an advertised lifespan of one year. Bulb B costs $2 and has an advertised lifespan of two years. But Bulb A's lifespan is based on usage of five hours per day, and Bulb B's lifespan is based on usage of two hours per day.
Bulb A, then, would get you 1,825 hours of use (365 days X 5 hours per day). Bulb B would get you only 1,460 hours of usage (730 days X 2 hours per day). You'd be paying a dollar more for 365 fewer hours if you used Bulb B.
Calculate Your Usage
Calculating your usage is just a matter of counting the hours during which the lamp with the bulb will be on. So if you know that you use a particular lamp for an hour in the morning and then five hours in the evening, you know that whatever bulb you use in that lamp will be used for six hours per day, on average. For the sake of simplicity, don't worry about variations here. Just find the general amount of time that the lamp is on and the bulb is in use.
Compare Usage to Advertised Lifespan
Find the daily usage amount advertised on the bulb package. There will be a sentence stating that the lifespan was based on X number of hours per day. Multiply that number by 365 to get the yearly usage, and multiply the yearly usage by the number of years the package states the bulb will last overall. Then, divide that overall number by the number of hours per day you'll actually use the bulb.
To break down the steps:
- Advertised bulb usage: 2 hours per day (hypothetical example)
- Multiply that by 365: 730 hours per year
- Multiply that by number of advertised years (hypothetical example of two years): 1,460 hours of use overall
- Divide the overall hours by the hours per day you use the bulb (six in this example, so 1460/6): 243 days, result rounded down
So that bulb would last approximately 243 days instead of two years given your usage. Do that procedure for each bulb you're considering, and then look at the prices relative to the number of days each bulb would last when you use it. That will give you a clearer picture of what you're really paying for.
If you'd like to get more information about finding the right light bulbs for your home, talk to a company that specializes in selling only bulbs, not just electronics or lamps in general. They will know all there is to know about bulb life span and getting the most for your money.
To learn more about light bulbs, contact a company like Pacific Lamp Wholesale Inc.