You’ve heard it many times before, probably to the point of hating the phrase, but the truth is that you can save yourself a substantial chunk of change each month by switching out your incandescent and halogen bulbs for a more efficient option. If you are doubting the real world saving that you can expect from using energy efficient lighting, this simple calculation will help you to figure it out very accurately.
To calculate the cost of running your present halogen or incandescent bulbs all you need is the wattage of the bulbs, the price you’re paying per kilowatt hour (found on your power bill), and a calculator. Now I’ll walk you through an example.
(Note: Kwh means Kilowatt hours.)
Watts x hours in use per day = total watts used per day.
Watts used each day divided by 1000 = Kwh used each day.
Kwh per day x 30 = Kwh per month.
Kwh/month x cost/Kwh = cost per month.
Employing this method we can easily figure out the cost of running a 100 watt incandescent or halogen light bulb. A bulb like that in your sewing room might well be on for 10 hours per day. (No, that’s not an overstatement. Lots of lights run more than an average of 10 hours per day, especially in winter.). As a for instance, we’ll use twelve cents per kilowatt hour as your electricity cost, though this might be a low estimate depending where you live. Check your electric bill to see what your actual cost is per kilowatt hour.
10 hours run time for a 100 watt bulb = 1000 watts per day.
1000 watts used each day = 1 Kwh daily.
1 Kwh per day x 30 days = 30 Kwh per month.
30 Kwh x 12 cents/Kwh = $3.60 per month. That’s how much it costs to run a single 100 watt bulb.
To discover how much a compact fluorescent bulb would save, we follow the same steps. A 23 watt compact fluorescent will usually replace an incandescent bulb of 100 watts; if you are used to halogen bulbs you may want to use a somewhat higher wattage, such as 25 or 27.
10 hours times 23 watts = 230 watts daily.
Divided by 1000 = total of 0.23 Kwh per day.
30 days multiplied by 0.23 Kwh = total of 6.9 Kwh.
6.9 Kwh x $.12 = $.83 per month. That’s a reduction of $2.77 (or 77%) in one month for one bulb.
Swapping 10 halogen or incandescent 100 watt bulbs for compact fluorescents would put $27.70 back in your wallet each month.
To figure out exactly how much you would save by replacing all your bulbs with compact fluorescents, simply use the same calculation, matching the wattage of your present bulbs with their energy efficient equivalent. Since you can now find these bulbs in a wide array of sizes and styles, with numerous bases for various fixtures, it’s not hard to make this change. Also, a lot of compact fluorescent bulbs are now available in versions that are compatible with a dimmer switch, and you can replace your outdoor bulbs as well because they come in heavy duty styles.
The initial cost of a compact fluorescent bulb will be higher, yes. The added cost will not eat up your savings, though; apart from the decreased power costs, compact fluorescent bulbs will typically have a much greater lifespan than halogen or incandescent bulbs. A gradual change to energy efficient lighting, by changing a small number of bulbs each month, will help to distribute the extra cost of these lights; the reduction in your electrical cost will pay for the bulbs during the first two months.
You’ll want to retain your receipts for the compact fluorescent bulbs because they are typically covered by a long term warranty. To make sure you can claim a replacement bulb on the guarantee if necessary, jot down a note on the packaging or the receipt indicating which bulbs were put into each fixture.
Using energy efficient light bulbs can certainly save you a nice chunk of change, and you can visit the Energy Resources Journal for more energy saving strategies to cut power bills even more.
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