Appliance energy saving

How to assess the energy saving of a new product, to decide whether its worth replacing to cut costs.

TV example

In considering replacing a CRT TV...

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)

1. Consumption = 0.1kW x 2hrs = 0.2kWh per day = 73kWh / yr
2. Price of electricity = 12p/kWh
3. So annual energy cost = 73 x 12p = £8.76 / yr
4. If typical life expectancy of appliance = 8 yrs, thats £70 of electricity per life of the product.

Now compare an LCD with 70w consumption

1. elec cost = £6.13/yr = £49/ 8yrs
2. Difference = 70-49 = £21

The purchase price is greater than the electricity saving, so the LCD never pays its savings back.

Real consumption

Ratings plates give maximum consumption, and this isn't always the same as real world consumption. Most LCD TVs & monitors consume the same power regardless of program content, CRT power consumption varies according to picture brightness, thus is below max rating a lot of the time. So in practice the figures are more in favour of the CRT set than the ratings plates suggest.

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