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You are replacing five 60 Watt incandescent light bulbs with five 18 Watt fluorescent light bulbs. You use these lights an average of 4 hours each day.
EnergyMultiply the bulb wattage by the number of hours in use and divide by 1,000 to get kilowatt hours (kWh). We are evaluating both bulbs for one year. This is 1,460 hours (365 Days X 4 Hours Average Use Per Day).
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60 watts | X | 1,460 hours | = | 87.6 kWh |
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| 1,000 hours | |||||
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18 watts | X | 1,460 hours | = | 26.3 kWh |
| 1,000 hours | |||||
Subtract the fluorescent bulb energy used from the incandescent bulb energy used to find the energy saved. Multiply by 5 to determine your savings for replacing 5 bulbs.
| 87.6 kWh | - | 26.3 kWh | = | 61.3 kWh | X | 5 bulbs | = | 306.6 kWh Saved |
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Dollars
Your cost per kWh is approximately $0.1237.
| 306.6 kWh | X | $0.1237 | = | $37.92 Saved |
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Environment
For each kWh of energy used, approximately 2.2 pounds of carbon dioxide (CO2) are emitted when fossil fuels are used to generate electricity.
| 306.6 kWh | X | 2.2 pounds CO2 | = | 679.4 pounds CO2 Avoided |
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Light Bulbs
Over the lifetime of your new bulbs, you would use 40 incandescent bulbs (1,000 hour lifetime)
compared to 5 fluorescent bulbs (8,000 hour lifetime)
Although one fluorescent bulb costs more (approximately $5) than one incandescent bulb (approximately $1), you will likely spend less money on light bulbs over the lifetime of each fluorescent.
The Power of Working Together
Madison Gas and Electric company's service territory includes 157,000 residential customers. If we all replaced five incandescent bulbs with fluorescent bulbs, our savings would be...
* Assuming an average difference of 51.9 watts between the old and new bulbs
Madison Gas and Electric company's service territory includes 157,000 residential customers. If we all replaced five incandescent bulbs with fluorescent bulbs, our savings would be...
| 51.9 watts * | X | 1,460 hours | X | 157,000 customers | X | 5 bulbs | = | 59.5 Million kWh Saved |
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| 1,000 hours | ||||||||
| 59.5 Million kWh | X | $0.1237 | = | $7.4 Million Saved |
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| 59.5 Million kWh | X | 2.2 pounds CO2 | = | 131.8 Millions CO2 Avoided |
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* Assuming an average difference of 51.9 watts between the old and new bulbs
