Difference between revisions of "Appliance energy saving"
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| − | First you | + | First you need to know the power consumption of the 2 sets you want to compare. The label on the set indicates the max consumption, and figures can be calculated from those. If you want more precision, you'd hook the 2 upto an energy consumption meter (killawatt etc) and measure their consumption exactly. |
Example: | Example: | ||
| − | Say a TV eats 100w and you watch it for 2 hr per day. (I'm picking easy figures) | + | Say a CRT TV eats 100w and you watch it for 2 hr per day. (I'm picking easy figures) |
# Consumption = 0.1kW x 2hrs = 0.2kWh per day = 73kWh / yr | # Consumption = 0.1kW x 2hrs = 0.2kWh per day = 73kWh / yr | ||
# Price of electricity = 12p/kWh | # Price of electricity = 12p/kWh | ||
# So annual energy cost = 73 x 12p = £8.76 / yr | # So annual energy cost = 73 x 12p = £8.76 / yr | ||
| − | # If typical life expectancy of appliance = 8 yrs, thats £70 per life of the product. | + | # If typical life expectancy of appliance = 8 yrs, thats £70 of electricity per life of the product. |
Now compare an LCD with 70w consumption | Now compare an LCD with 70w consumption | ||
| − | # cost | + | # elec cost = £6.13/yr = £49/ 8yrs |
# Difference = 70-49 = £21 | # Difference = 70-49 = £21 | ||
| − | + | The purchase price is greater than the electricity saving, so the LCD never pays its savings back. | |
Revision as of 14:44, 19 September 2010
The reduced energy use never pays back the added purchase price on a new LCD TV.
How would you go about calculating that ?
First you need to know the power consumption of the 2 sets you want to compare. The label on the set indicates the max consumption, and figures can be calculated from those. If you want more precision, you'd hook the 2 upto an energy consumption meter (killawatt etc) and measure their consumption exactly.
Example:
Say a CRT TV eats 100w and you watch it for 2 hr per day. (I'm picking easy figures)
- Consumption = 0.1kW x 2hrs = 0.2kWh per day = 73kWh / yr
- Price of electricity = 12p/kWh
- So annual energy cost = 73 x 12p = £8.76 / yr
- If typical life expectancy of appliance = 8 yrs, thats £70 of electricity per life of the product.
Now compare an LCD with 70w consumption
- elec cost = £6.13/yr = £49/ 8yrs
- Difference = 70-49 = £21
The purchase price is greater than the electricity saving, so the LCD never pays its savings back.