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New Technology: LED Bulb Payback Times
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Not everyone is interested in just saving energy - many want to know they will save enough money to pay for their investment! At around £16 each, these dimmable LED bulbs are not cheap, but the price will inevitably come down as the technology is developed.
| Data for 8 Bulbs | Halogen | Dimmable LED |
| Power (W) | 400 | 42 |
| Power (kW) | 0.40 | 0.042 |
| Daily Use (h) | 2 | 2 |
| Daily Energy Use (kWh) | 0.80 | 0.084 |
| Annual Energy Use (kWh) | 292 | 30.7 |
| Annual Energy Cost (£) | 40.88 | 4.30 |
The bottom row of the table shows that the energy saved in a year would pay for over 2 of the LED lamps! But let's do some more precise calculations. Grab a pen, some paper and a calculator and then answer these questions. Check your answers at the end, or click for hints!
- What is the cost of 8 LED lamps for the kitchen example above?
- How much money is saved per year if they're used for 2 hours a day on average?
- Calculate the payback time, in years, for buying 8 lamps, used for 2 hours a day.
- Totalight's website suggests an LED lamp "pays for itself in 18 months". How many hours would the kitchen LED lamps have to be used for a payback time of 18 months?
- Explain whether or not a payback time of less than 18 months would be achievable in a school or office using LEDs instead of halogens.
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