For a fridge it is a little different, as it is a 24/7 running device. But it is also not rocket science. No need to invent a more efficient compressor, just a little more isolation and the compressor is less often running and consuming energy.
The industry is always looking for the most efficient way to make things happen for them. 
3 Likes
btw, as we talk about dishwashers:
Does anybody question why you only can buy whashing tabs anymore? Or gel packs for washing machines?
There is an alternative. My partner used to make her own dishwashing blend consisting of baking soda, citric acid, sea salt, and vinegar. If you buy it in bulk and mix it yourself it is a lot cheaper than tabs, but it does cost some effort. It generally worked fine, but sometimes it wasn’t aggressive enough (for example red marks from tomato sauce).
1 Like
No.
kW·h or kWh is kW times hours.
kW per hour would be kW/h.
Notice how the Wikipedia article uses “annual” or “per year” in connection with this unit.
When you buy an appliance, the shop or the data sheet will usually list how much electricity the appliance uses within a year measured in kWh, because that’s the unit also used in your electricity meter (how could that go up constantly if it was kW/h) and when you pay your electricity bill for the year so you can easily calculate the impact of the appliance on your electricity bill, and if you have a look at that, then indeed
It does if you want to use less energy.
It does not always if your priority is on saving money overall, depending on whether the energy cost savings over time make up for the price or price mark-up for the more energy-efficient appliance.
And it does not if you scrap a perfectly fine appliance just to get an energy-saving one, because … Ok, we’re Fairphoners, we know why 
.
6 Likes
I need to contest.
On your energy bill you pay the “kWh” of energy you consumed per year. Thats correct so far.
The actual sheet for energy rating does not show the used energy anymore. Now it shows the EEI (energy efficiency index)
Also on the label is shown: “the energy consumption in kW·h /cycle”
That means basically the used “kW” times hours as you correctly point out.
But what does it mean?
Example: If our machine consumes 2 kW per cycle within one hour, the energy rating would be very bad. But if it consumes the 2 kW within 3 hours, the energy rating suddenly is much better. And this is how the energy rating works.
For the consumer it doesen’t matter in which time the consumption happens. The consumer needs to pay the used kWh.
So I do not see any improvement to implement the cycle time in the EEI. The consumption per cycle is what matters.
Totally agree.
1 Like
No.
The energy rating is not reliant on per hour, it’s reliant on per cycle.
The cycle is the constant against which the variable energy consumption of the different machines gets compared.
You are correct in that the cycles tend to run longer, but that’s how the machines save energy (and also in the case of washing machines and dishwashers: water).
The machines do the same task. And the energy rating rates how much energy they use for the task.
Your example, dishwashers:
“After 2010, a new system is used, based on an energy efficiency index (EEI), which is based on the annual power usage, based on stand-by power consumption and 280 cleaning cycles, relative to the standard power usage for that type of dishwasher. For a 12-place-setting dishwasher, an EEI of 100 corresponds to 462 kWh per year.”
Now …
An A+++ machine uses stand-by power and does 280 cleaning cycles.
The EEI < 50 for it means it uses less than 231 kWh (50% of 462 kWh) per year.
An A+ machine uses stand-by power and does 280 cleaning cycles.
The EEI < 63 for it means it uses less than 291,06 kWh (63% of 462 kWh) per year.
The A+++ machine saves you about 60 kWh electricity per year compared to the A+ machine under the terms given for the comparison.
Totally correct.
And an A+++ dishwasher uses less kWh than an A+ one for the same task as per the EEI.
Good, because the cycle time is not implemented in the EEI.
Totally correct. And that’s what the EEI compares (ignoring stand-by consumption as a low factor in this).
7 Likes
I’ve come to understand it the way @AnotherElk explained. If it isn’t, then a lot of sources such as comparison websites and test websites are in the wrong. So wrong, that it could warrant a scandal.
1 Like
It obviously is the way @AnotherElk explained.
If you take a look at those labels in shops this is evident.
Almost all of the appliances give the engery consumption per year. And as that is always based on e.g. for washing machines a fixed amount of washing cycles, one can quite easy compare the different energy labels; with A+++ always being more efficient than A++ and even more than A.
EU-regulations might seem nonsensical at times, but usually they do what they intend to; in this case label energy consumption by efficiency.
Edit:
Ok, this might not be the most innovative solution and it uses more materials, but it still saves energy. And I guess more energyefficient compressors will be developed nevertheless (even if they don’t do it for fridges in the first place, but can use it for them later).
1 Like
kW itself means kilojoule per second. There is no such thing as a total kW usage in one cycle, kW just tells you how much a device is consuming at the moment and you need to multiply with some unit of time to get energy (seconds to get energy in kJ, hours to get energy in kWh).
I think this is what caused the confusion.
5 Likes
As others have pointed out, kW is not a unit of energy but of power. Think about e.g. a 20 Watt lightbulb. When the bulb is on, it’s drawing power at 20 Watt which is 20 Joule/second, in other words the energy used in one second is 20 Joule. As the Joule is quite a small unit for “daily life” applications, energy is also commonly expressed in another unit, the kWh. For the 20W lightbulb one can say that if you leave it on for one hour, it has consumed 0.02 kWh.
Now back to the washing machines: if a cycle uses 2 kWh, it does not matter how long the cycle is, the total energy used will be 2 kWh. It may be a 1 hour cycle for a machine using on average 2kW of power, or 2 hours at 1kW, or 30 mins at 4kW, etc… In each of these cases the total energy used is 2kWh and the labels make sense.
5 Likes
Lay the clothes into sunlight for some hours and the UV-light destroys red stains. 
1 Like
Does that really work? For pots and pans and plates as well?
(Cause @JeroenH gave a receipe for a detergent for the dishwasher.)
2 Likes
I thought we were talking about washing mashines…
3 Likes
You have completely misundertood thé meanibg of kWh.
KWh is a measure of energy. Using one kilowatt for one hour is the same as using two kilowatts for 30 minutes or half a killowatt for two hours.
From the wikipedia article you cite:
“The energy efficiency index is in kW·h per kilogram of washing, assuming a cold-water supply at 15 °C.”, so just washing more slowly would not improve the rating.
3 Likes
@JohnHughes, I think that it has been pointed out a few times already and the misunderstanding has been cleared up by now.
2 Likes
Curse of the tiny screen, didn’t see all the other replies.
Actually, kW/h wouldn’t mean anything because kW is not a quantity, it is already a kind of ‘speed’: kJ/s.
1kW is the power that you need to accomplish 1000 Joule work in one second, so 1kW/h would be the power boost you need to increase your power by 1000/Joule per second every hour. Or not?
1kW= 1kg * m²/s³
1kW/h=0.2777kg * m²/s⁴
Though I’m not sure physics needs units for power boosts.
PS: Actually, no.
kW is actually already a kind of acceleration, so it really makes no sense to add another power to time.
1 Like
^
Source: https://de.wikipedia.org/wiki/Watt_(Einheit)
Speed? In an abstract way, if you think of electrons.
@ElKrasso, ‘speed’ doesn’t always have to be ‘distance’ over ‘time’. In music, speed is the rate at which ‘beats’ are passed. So, indeed in an abstract way, you could say ‘power’ is the rate at which ‘energy’ is passed.
1 Like