Sunday, 21 September 2014

When energy efficient appliances are worth while

There are some kinds of appliances, such as tumble dryers, where a good energy rating really does save you money. However energy labels don't tell you how much an appliance costs to run, they only tell you the estimated kWh/year. So DECC and John Lewis ran a trial to see if putting the lifetime cost of electricity on the energy label encouraged people to choose a more efficient appliance. The total cost is then the price plus the lifetime cost. They found the extra information had a significant effect on sales for tumble dryers, though not for washing machines. However, even where the cost savings aren't that great there are other reasons to buy appliances that use less energy - like helping to keep the lights on at peak time.


John Lewis's five best selling washing machines include two A+++ rating, two A++ and one A+. The difference in energy use between an A+++ and an A+ model is around 30 kWh/year - costing £35* over 9 years - not much really. The best selling condensing tumble dryer is a B, estimated to use 561 kWh/year. The third best is an A++ using only 212 kWh/year - over 9 years that will cost you £408 extra. In the case of the tumble dryers the A++ works out 13% cheaper, even though it is more than twice the cost up front.

Two of the top selling washing machines from John Lewis
Washing machines Rating Price kWh/year Annual cost
of electricity*
Lifetime cost
(9 years)
Bosch exxcel waq28461gb A+++ £399 179£23 £608
John Lewis JLB1WM1402 A+ £429 204 £27 £668

Two of the top selling tumble dryers from John Lewis
Tumble dryers Rating Price kWh/year Annual cost
of electricity
Lifetime cost
(9 years)
Beko DCU8230W B 219 561 £73 £875
Bosch WTW863S1GB Sensor A++ 509 212 £28 £757

Now obviously these running costs are only estimated - your savings would depend on how often you use your machine and what you do with it. For tumble dryers, the annual consumption is based on running it 160 times per year (just over 3 times per week), about half the time on full load and other times on a partial load. If you use your machine less than this the savings will be less and vice versa. If you only use the tumble dryer when you can't use a washing line - say 1/3 of the time - then you can cut your electricity use without splashing out on an expensive dryer.

I also looked at televisions. All the ones I found were A or A+ rated and there wasn't that much difference in power consumption until you get to the larger screens - but they cost a lot more up front as well. If you are prepared to pay an extra £400 for a 48" screen then you won't be fussed about a few more £s a year in electricity costs.

However, televisions are often used at peak times. If you are concerned about keeping the lights on as well as saving money, that is another good reason to consider TV power consumption (see How to avoid brown outs this winter). For example, a saving of 30W (perhaps a 32" screen instead of a 48" if both are A+) in every household in the UK would cut total demand by 0.81 GW - that is 1.6% of peak demand in December 2013. Margins are so tight now that this sort of saving could make a big difference.

And let's not forget climate change. Saving 30W on TV power consumption, 4 hours a day, saves 20 kg of CO2 over a year - without you having to think about it or change your habits at all. If every household in the country did this, we could save half a mega-tonne of CO2.

* assumes 13p/kWh and ignoring inflation - your savings will increase as electricity prices go up.

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