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The £ savvy way to buy a dishwasher

The headlines

This article aims to help you understand how much energy it is likely cost to run a dishwasher when you are choosing, to help you make comparisons and decisions.

For 25 years, kitchen appliances were rated using an A to G energy labelling scale to help you choose the most economical products to buy.

BUT the system doesn't tell you the difference in actual running costs. How do you know how much you will save by going for an C rated dishwasher compared to a D rated dishwasher for example?

I'll show you in this article how to calculate the likely actual energy costs using the manufacturers published energy consumption figures for a given product. This manufacturer information is always written as the number of 'kWh' on product literature and on energy labels in showrooms.

Using this method will give you much more useful purchasing information than using the simple A-G scale.

The energy scale system changed significantly in March 2021. Unfortunately, this means there is still a very confusing mix of old and new style information out there.

I hope in this article to give you a clear explanations of what you see and what it means.

It is also commonly thought that to get the most energy efficient appliance means buying the most expensive products. I'll show you here how big the differences can be.


How to work out what the appliance will cost you to run

It's important to mention for information, that the labelling system was completely changed in March 2021 so don't be alarmed if you only see products that are showing energy efficiencies E or F!

The information for dishwashers is shown in two ways currently...not terribly helpful!

I show and explain the calculations for both ways separately the next two sections:

1) When you see product labels on dishwasher in showrooms

On product labels in showrooms like the one in the picture below, the figure is now shown next to the symbol with 100 next to it with the circular arrow around it. This means in the example below that this dishwasher uses 104kWh of energy for 100 wash loads, so roughly twice a week for a year.

These figures are all for the ECO wash programme. From my experience you use the most intensive wash programmes the energy use and costs will be double these figures. Normal wash programmes will be somewhere between the ECO and intensive cycles.

Dishwasher owners manuals will usually tell you the differences in energy use for different programmes.

So, if your tariff for electricity is similar to the standard tariff from October 2023 of 27p per kWh the cost of energy for year works out at 104 x 0.27 = around £28 if you are likely to use it twice a week.

As this is the figure for 100 washes. To get the 'per wash' figure divide this figure by 100

So, £28/100 = £0.28 (so 28p). So, the cost per wash load is 28p.

If you think you would do more wash loads than twice a week, say every day of the year, then it would cost.

28p x 365 = around 10,220 pence (so £102).

2) Dishwasher product information online

Online information usually just says 'energy use per year' or 'annual energy use'. This assumes you do 280 washes per year.

So if a dishwasher advert online says 250 kWh for example then the annual cost assuming your tariff is the standard 27p per kWh is

250 x £0.27 = £67

This is the cost 280 wash loads. To get the cost for each wash load divide this figure by 280.

£67/280 = £0.24 (24p). So, the cost per wash load is 24p.

If you think you will use the dishwasher every day, then to get the yearly cost multiply this figure by 365 days.

365 x £0.24 = £88


Dishwasher costs on unusual energy tariffs

Economy 7. The above costs will be around 20% higher if you use a dishwasher machine during the hours of the daytime tariff if you have a dual rate Economy 7 type tariff, and around 50% lower if you use the dishwasher during the hours of the night-time rate.

Other flexible tariffs. Increasingly, there are other tariffs which have different energy costs for different times of day, such as for homes with electric cars, heat pumps, and to help the energy grid. Tariffs like these would allow you to run your dishwasher when the energy is cheaper, although the energy at other times will be more expensive. If you think you might switch to tariffs like these in the future, then it will be important to choose a machine that includes a timer to control the start time of the machine. Some machines may even have smart features that will automatically run when the energy cost is cheapest. These tend to be more expensive machines though.

If you need any specific guidance on working out any of the above do drop me a line through the web site and I'll see if I can give you some pointers.


Real showroom comparisons and examples

These are both Hotpoint models in my local showroom, with labels showing the number of kWh for 100 washes. In this case the more expensive machine is rated E on the label does use slightly less energy than the cheaper F rated machine.

Don't forget these costs are when using the ECO programme and they will be higher for normal and intensive wash programmes.

I find a web site also very useful for researching the energy use of any type of domestic appliance.


The geeky area

The story about labelling changes and reason for this blog

The energy labelling on kitchen appliances has been around for 25 years with a scale going from A to G to indicate how energy efficient a product is.

We have become use to most products being at least A rated, or over the years A+, A++ and even A+++ as manufacturers have made products that are more and more efficient. When the scale was originally invented the industry didn't realise that A was not going to be high enough.

In March 2021 the scale was drastically revised for many product types including kitchen appliances. Depending on the type of appliance what might have been an A++ appliance before might now be an D, E, or even F on the new scale. The reason for this is to give a new challenge on the manufacturers to further improve energy efficiency and move UP the new scale.

This is why you shouldn't be alarmed that most products are only E or F rated these days!

The problem has always been though, how does a consumer calculate how much energy two similar products use, and what will that difference actually make to annual bills? If a consumer sees a D rated product next to an E rated product it is not clear how much money will be saved on using the D.

This is an example of text from one website advert for a dishwasher:

'E energy rating means it may not be the most efficient, but it still won’t add too much to your monthly utility bills'

I don't think that is very helpful!

A lot of the information online is also very confusing. This screenshot is actually for a freezer, but equivalent dishwasher information can be similarly confusing. It shows all sorts of energy performance ratings without any explanation.

Thankfully the one important thing that all these products show as you can see at the bottom is a kWh figure.

The kWh figure should by law be displayed on the energy label on all appliances in showrooms. For online buying, the kWh is sometimes buried in the 'more details' or 'full specification' section for a product and will need digging out with Google.


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I run this website as a hobby, because I care about this stuff, and do it for no commercial purpose. If you have valued what you've seen, please tell other people about it.

If you have any other suggestions for additions or changes to site content do please let me know. While I have made every effort to ensure that the information contained on this website is correct, I cannot take responsibility for errors or omissions.

All content on the site should be treated as information and not advice. You should take professional advice where appropriate to different site articles.


Mark Thompson

Get Energy Savvy - simple practical home energy efficiency information

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