Sunday, 12 April 2009

Designing your own electricity system - part 7 (fridges)

Here are some specifications regarding energy saving fridges.

Tafelberg sell some of the Ardo range of fridges.

The Ardo rating is: 130KWH rating per year. Even if it really uses 165KWH per year, that will be amazing as an A++ energy star fridge is rated at 380KWH per year and a normal fridge much higher than that.

My normal fridge (which I still need to replace) uses approximately 660 kwh per year which at 70 cents per kwh (my rate) is about R40 per month. Note that this is only based on one day's usage. After a few months, I will have a more accurate number.

The Ardo fridge uses about 40Watts when it is on and is so quiet that a friend on mind has it in his passage outside two of the bedrooms.

At 165kwh per year , the Ardo fridge costs R10 per month.

A normal fridge is about R2000 and an Ardo fridge is about R8000.

The difference is R6000, so R6000 / R30 (saving) = 200 months = 17 years. Not a very good payback period, but remember what I said in an earlier part of this blog series. The R6000 is locked in, ie there is no inflation. If electricity goes from 70 cents to 91 cents (30% increase), then the payback period is R6000 / R37.50 = 14 years. On so on.

The saving becomes clearer once we start looking at the costs of generating electricity compared with saving electricity.

Note that there are going to be paradoxes in this discussion. Whilst it is more expensive to buy an energy saving fridge, the more people buy them, the more the price will come down. If one adds in the environmental savings, then the total environmental costs are even lower.

If I have made any mistakes in my calculations please let me know so that I can fix them. In these cases, please let me know if I can publish your name as the person who found the mistake?

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