Dishwasher Power Consumption: Electricity Use by Setting
Dishwasher power consumption is supposedly revealed by the appliance star rating. However, as you'll see in this article, the electricity usage of dishwashers is not that simple.
For starters, the energy rating system only convey and compare one thing. For dishwasher electricity use, it's the energy usage of 7 loads per week at the ‘normal’ setting.
In other words, there is no indication of available settings, nor their impact on dishwasher energy use. As it turns out, you can save a lot of power, just by changing the settings.
How Much Power Does a Dishwasher Use?
The following are real-world test results from my several-years-old "3 Star" Beko dishwasher. I used a Power Mate Lite to make the power measurements. If you want to do some testing yourself you can buy a power consumption meter here.
|P2 30 Min||35˚C||0:30||0.72 kWh|
|P3 Eco - Half Load||45˚C||1:55||0.82 kWh|
|P3 Eco||45˚C||2:31||0.93 kWh|
|P8 Auto||40˚C - 65˚C||2:34||0.93 kWh|
|P4 Quick & Clean||60˚C||0:58||1.23 kWh|
|P5 Intensive||70˚C||2:23||1.37 kWh|
Setting options - your choice has a big impact on dishwasher power consumption.
These results clearly show that the settings you choose have a big impact on dishwasher energy usage per load. For example, simply changing from 'Quick & Clean' to 'Eco' reduces energy consumption (and cost) by about 25%.
In my experience, the Eco mode is just as effective as the others. You can save even more by switch to the 'half load' option which also works just fine. The short '30 Min' load showed even bigger savings, but it is only suitable for very light loads (and some hand drying is required).
Another important result is that the temperature level is more important than time taken. Generally speaking, the higher the temperature setting, the higher the energy usage. You can use this result as a rough guide to choose a more efficient option on your dishwasher.
See Also: Appliance Electricity Cost Calculator
Dishwasher Electricity Usage by Star Rating
At the time of purchase, it's often hard to know how different one star rating is to another. With the above real world usage table in mind, we can now review what the star ratings actually mean in terms of dishwasher electricity usage. The data shown below is for a '14 place setting' dishwasher.
|Dishwasher Star Rating||Dishwasher Electricity Usage (per load)||Annual Cost*|
|1 Star||1.84 kWh||$192|
|2 Star||1.28 kWh||$135|
|3 Star||0.90 kWh||$94|
|4 Star||0.63 kWh||$66|
|5 Star||0.44 kWh||$46|
|6 Star||0.31 kWh||$32|
*Based on 365 loads per year and an electricity cost of $0.287/kWh. Source data is from the Energy Rating website.
From these results you can see that choosing a higher star rating can have an even bigger impact on energy usage than merely changing settings. However, this comes with a big caveat: the vast majority of dishwashers on the market tend to hover quite closely around the 3 to 4 star range.
In other words, a very high rated device may simply not be available at an affordable price. In which case, your best bet is still to play around with the settings you have available, and choose the lowest temperature option that works for you.
My dream dishwasher: an as yet unavailable / only theoretical 7 star dishwasher with next to no electricity usage.
Other Ways To Save
As you may have gleaned, the key energy using part of a dishwasher relates to heating the water. So, if you already have an efficient hot water system (such as solar or heat pump powered by solar) you may wish to use a dishwasher model which allows a hot-water supply rather than the usual cold-water supply. However, for this to work effectively your dishwasher would need to be quite close to your hot water system.
Don't forget that the best way to save energy would be to reduce the total number of loads you require. So if you can do a load say every 1.5 days, rather than daily, that will save even more energy again.
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