Do appliance eco modes actually save money? Here’s when they work – and when they don’t

Eco modes on household appliances can seem a little too good to be true, especially for budget-conscious households like mine.

A dishwasher that runs for four hours hardly sounds cheaper than one that finishes in 60 minutes, while a tumble dryer’s eco setting may keep turning long after the standard cycle would have stopped.

Longer running times do not necessarily mean higher bills, though. Many eco programmes save energy by using less heat or water, then giving themselves more time to do the same job.

The savings can be worthwhile – but some appliances, like the best dishwashers, benefit far more than others.

Why can a longer eco cycle cost less?

Mainly because running time is only part of the picture. Heating water or air usually takes far more electricity than turning a drum or pumping water around a dishwasher. An eco programme can therefore run for longer while still using less energy overall.

On a dishwasher or washing machine, that usually means cooler water and more time spent soaking or moving the load around. Other appliances may reduce suction or heat output instead.

The important point is that “eco” does not describe one standardised setting across manufacturers – it depends on what the appliance is designed to do.

Dishwashers: where eco mode is best

Dishwashers are one of the clearest examples of an eco mode doing what it promises. The programme heats less water and gives dishes longer to soak, so it can use less electricity even though the cycle takes much longer.

In a Which? snapshot test based on five washes per week, eco programmes cost around 30% less to run than the machines’ main settings. You are most likely to see that benefit with a reasonably full load of normally soiled dishes.

Of course, loading still matters. Large food scraps should be removed, spray arms need room to turn, and the filter should be kept clean, or else you may end up washing the same plates twice and wiping out the saving.

Washing machines: why eco mode and low-temperature are not the same

Washing machines save most of their energy by heating less water, but there are two slightly different ways to do that.

Eco 40–60 is a standardised programme for normally soiled cotton items labelled as washable at 40°C or 60°C. It is also the cycle used to calculate the machine’s energy-label performance, although the water does not necessarily stay at either temperature throughout the wash.

Choosing a normal 30°C or 20°C cycle is a separate option. Lower temperatures need less electricity and are usually enough for everyday clothes. For routine loads, eco mode or a cooler wash should work well, and this is certainly the case in my experience.

Tumble dryers: the important exception

Perhaps unsurprisingly, tumble dryer eco modes are less convincing. They usually lower the heat and extend the cycle, but the saving can be fairly small.

Which? found an average energy reduction of just 3.7% across the models it tested, while some eco programmes left clothes noticeably wetter than the standard setting. Any second cycle would quickly wipe out that energy saving.

You can often make a bigger difference by using a fast spin in the washing machine first or avoiding an overloaded drum.

The dryer itself matters more than the button, too. A heat-pump model will generally use far less energy than a traditional vented or condenser dryer. The Hoover H-Dry 350, which we loved when we tested it, is a useful example of how that tech works in practice.

Eco modes on other appliances

Elsewhere, the eco label can be much less precise. A cordless vacuum may reduce suction, while a heater could lower its power output or adjust the thermostat more cautiously.

Both can use less electricity, but only if the reduced performance still does the job. Vacuuming the same carpet twice or running a weak heating setting for much longer is unlikely to save anything overall.

Should you use eco mode?

For dishwashers and washing machines, eco mode is most often the best default for full, normally soiled loads.

Tumble dryers deserve more caution, especially when the programme leaves clothes damp enough to need another cycle, defeating the purpose of trying to save some energy.

In practice, the cheapest option is usually the one that cuts heat or water without making you run the appliance twice.