How Is Energy Consumption Measured?
Hi All,
How are the energy ratings of washing machines calculated?
Are readings taken across a whole cycle? Are they based on consumption of energy per minute?
It struck me that A rated appliances just might not be as efficient as people believe. Yes, they use less electricity at any particular point in time but if they take longer to wash the clothes....
Solution Summary
AI-generated from this discussion
This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.
Washing machine energy ratings are based on a specific test cycle, not all programmes
- The problem
- The question asked how washing machine energy ratings are measured and whether an A-rated machine might only appear efficient because it uses less power at any moment but runs for longer overall.
- Likely cause
- The accepted explanation was that the rating is based on energy used during a specific wash cycle, stated in the discussion as the 60 degree programme. Contributors also said manufacturers may optimise that test cycle, so the published rating may not reflect the efficiency of other commonly used programmes.
- What fixed it
- No appliance fault was being repaired. The accepted answer was that ratings are taken from a specific cycle rather than averaged across all cycles. The discussion also suggested that heating the water is the main energy use, and that some machines may achieve strong ratings by using longer or altered 60 degree programmes. No exact repair or corrective action was applicable or confirmed.
- Checks to try
- Accepted reply stated the rating is based on a specific 60 degree wash cycle
- Forum replies said the water heating stage is the main energy consumer
- Discussion cited reports that some machines did not actually reach 60 degrees on the 60 degree programme
Safety: Disconnect the appliance from the electricity supply before any inspection. Work involving mains electrics, gas or sealed refrigeration systems should only be carried out by a suitably qualified appliance engineer.
7 Answers
They are only based on the energy used during a specific cycle (60 degree wash I think), which is daft because hardly anyone uses that wash cycle any more!
People have often wondered about how eco wash cycles can be more economical when they take 2 or 3 times longer to wash, I have an article about this question, which might help - Why do economy wash settings take much longer?
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So the manufacturer *could* tune the 60 degree wash to be ultra efficient just to get the A+ rating, but not bother with the other cycles?
I suppose modern must soak the clothes for longer?
Though they would still have to heat the water to 60 degrees* and they can't get round that. It's only the heating of the water that really uses any energy worth worrying about. The motor and other parts use virtually nothing in comparison.
*Since writing this comment it appears they can cheat on the 60 degree cycle. Which? have tested many washing machines and found most didn't heat the water to 60 and some were woefully short - Washing machines not delivering right temperature
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So...another silly question.
Why do so many modern machines feature cold fill only when gas is cheaper per unit of energy?
Surely, it makes sense to fill the machine with water that's atready hot, then maybe heat it a few more degrees to reach the desired temp, than fill with cold water and have to heat it from scratch?
I have a lengthy article on the subject of cold fill washing machines
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If the washing machine has a good rating heating at 60C, why would it not be the same at others?
It's possible to tune the 60 degree wash (which is relatively rarely used) to get the best rating whilst the wash cycles used by most people may not be as efficient. Which? tested many washing machines and found that most didn't even reach 60 degrees on the 60 degree wash. One, only reached 43 degrees. So if your 60 degree wash cycle only gets to 43 degrees it's going to get a much better energy efficiency rating than competitors. Unfortunately it seems that the people testing the 60 degree wash cycles for energy efficiency weren't checking that they actually heated water to 60 degrees. There are other ways to get an excellent rating such as making the 60 degree cycle much longer knowing that most people don't use it so it gets better wash efficiency results. The most common wash cycle (40 degrees) could then be quicker but not wash as well to appease customers who get annoyed at long wash cycles.
As with all of these badges of honour and imposed tests, manufacturer's commonly find a way to cheat on them. I can't of course say that these manufacturers were definitely trying to cheat the energy ratings, but we all know of the recent scandal involving car manufacturers being fined for cheating the emissions tests so it's clearly something that happens.
Are eco labels on Washing Machines misleading?
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