The Great Autumn Laundry Experiment: What’s the Cheapest Way to Dry Your Clothes?

The cheapest way to dry your clothes might not be the one you think.

It is an ordinary autumn problem. The washing machine has finished, the sky looks threatening, and there is another load waiting behind this one.

Do you put everything in the tumble dryer? Arrange it on an airer? Switch on a dehumidifier? Or hang it outside and hope?

Each option has its supporters. Unfortunately, comparisons often overlook something important: an appliance’s power rating does not tell you how much it costs to finish the job.

A small appliance running all day can use more electricity than a larger one that finishes quickly. Equally, clothes drying “for free” indoors may be borrowing heat from your home and releasing moisture that you then need to remove.

So let us turn the weekly washing into a useful household experiment.

First, Define What You Mean by “Cheapest”

There are three different questions:

• Which method uses the least purchased energy?
• Which costs the least per finished load?
• Which offers the best overall value once equipment, time, space and moisture are included?

They do not necessarily produce the same answer.

Outdoor line drying uses no purchased energy for drying. A heat-pump tumble dryer can offer efficient, predictable results. A dehumidifier can help dry clothes that cannot go in a dryer while collecting moisture from the room.

The aim is to find what works in your home, with your washing and your electricity tariff.

The Calculation That Cuts Through the Claims

You need two figures:

Electricity cost = energy used in kWh x electricity price per kWh

If an appliance uses 1.5 kWh and your electricity costs 30p per kWh:

Cost = 1.5 x 30p = 45p

Throughout this article, I will use 30p per kWh as an illustrative tariff, rather than claim that everyone pays the same price. Replace it with the unit rate on your own bill.

The standing charge is excluded because drying another load does not normally change it.

For an appliance drawing steady power:

Energy used in kWh = power in watts / 1,000 x hours running

However, dryers and dehumidifiers can change their electricity consumption during operation. Measuring the whole cycle is better than assuming the label wattage applies continuously.

Four Ways to Dry a Load: An Illustrative Comparison

These are worked examples, not measured test results or guaranteed appliance figures. The assumed energy use and operating times show how the calculation works; actual results depend on the machine, load, spin speed, room and weather.

Drying method	Example energy use	Cost at 30p/kWh	Time and practical considerations
Conventional electric tumble dryer: vented or condenser, without a heat pump	4.0 kWh per load	£1.20	Predictable; measure your programme’s actual duration
Heat-pump tumble dryer	1.5 kWh per load	45p	Programmes can take longer; uses recovered heat
Dehumidifier and unheated airer	Average 250 W for 6 hours = 1.5 kWh	45p	Needs suitable space, airflow and room conditions
Outdoor line or airer	0 kWh of purchased drying energy	0p	Weather dependent; may need finishing indoors
Indoor unheated airer alone	0 kWh directly at the airer	0p direct electricity	May involve additional heating or ventilation costs

The interesting result is that the dehumidifier and heat-pump dryer cost exactly the same in these examples.

If that dehumidifier needs ten hours instead of six:

0.25 kW x 10 hours = 2.5 kWh

2.5 x 30p = 75p

That is why “only 250 watts” is an incomplete money-saving claim.

Compare energy per dry load, not watts per hour.

1. The Conventional Tumble Dryer: Convenient, but Check the Consumption

By “conventional”, I mean an electric dryer using a resistance heater, rather than a heat pump.

A vented model sends moist air outdoors through a duct. A conventional condenser model collects water in a tank or sends it to a drain.

These machines offer a substantial advantage: the weather does not decide when your towels are ready.

Their drawback is electricity consumption. Heat-pump dryers are generally more efficient than conventional vented and condenser machines. electricalsafetyfirst.org.uk

Before replacing an existing dryer, improve how you use it:

• Use the highest washing-machine spin speed suitable for the fabrics.
• Keep filters and other serviceable parts clean according to the instructions.
• Avoid overloading.
• Separate items that dry at very different speeds.
• Select the dryness level you actually need.

A shirt intended for ironing does not necessarily need to be dried as thoroughly as a towel going straight into a cupboard.

Energy Saving Trust recommends moisture-sensing controls to help avoid wasting energy through over-drying. Energy Saving Trust

2. The Heat-Pump Dryer: Longer Does Not Necessarily Mean More Expensive

A heat-pump dryer recovers and reuses heat within its drying process instead of continually supplying heat in the same way as a conventional machine.

This is a useful challenge to our instincts. A machine that runs for longer can still use less electricity overall.

Energy Saving Trust identifies heat-pump tumble dryers as a more efficient option. Energy Saving Trust

But lower running costs do not automatically justify buying a new appliance immediately.

Using our illustrative figures:

Saving per load = £1.20 - £0.45 = £0.75

If a replacement costs £400 more than the alternative:

Simple payback = £400 / £0.75 = approximately 533 loads

At four dryer loads a week, that is roughly two and a half years. At one load a week, it is over ten years.

This simplified calculation excludes repairs, finance costs and changing electricity prices. It also assumes those energy savings actually occur.

How often you use the dryer matters as much as the saving on a single cycle.

3. The Dehumidifier and Airer: Useful, but Not Automatically the Winner

When clothes dry on an airer, their water evaporates into the surrounding air.

A dehumidifier removes moisture from that air, helping maintain conditions in which more water can evaporate from the clothes.

It can be particularly useful when:

• garments are unsuitable for tumble drying;
• outdoor space is unavailable;
• a dehumidifier is already needed;
• you have a suitable room in which to spread washing out.

But performance depends on conditions. Dehumidifier type matters too: manufacturer Meaco distinguishes between compressor models for warmer rooms and desiccant models for colder conditions. Do not assume every model will perform equally well in a chilly utility room. Meaco (U.K.) Limited

Give the airer some breathing space

Unfold garments and leave gaps between them. A tightly packed airer can leave the middle items damp long after the outside ones have dried.

Follow the appliance’s instructions for placement and clearances. Keep clothes and drips away from the machine and electrical connections.

Avoid leaving a window wide open throughout a dehumidifier drying experiment: this continually exchanges the air you are trying to dry. However, do not block permanent ventilation or interfere with ventilation needed for safe combustion or indoor air quality.

One further measurement trap: the water in the tank did not necessarily all come from the washing. Some may have come from moisture already present in the room.

4. Natural Drying: Outdoors and Indoors Are Different Experiments

Outside: take advantage of the available weather

Outdoor line drying uses no purchased drying energy and keeps the evaporated moisture outside the home. Energy Saving Trust recommends it where possible. Energy Saving Trust

You do not need a hot summer afternoon. Clothes can dry in cool weather when conditions allow evaporation, particularly with useful airflow.

In autumn, partial outdoor drying can still help. Taking a load from wet to slightly damp outside reduces the work needed to finish it indoors.

Inside: the airer has no plug, but the water still has to go somewhere

Suppose, as a simple example, your spun washing weighs 6 kg and the same load weighs 4 kg when fully dry.

That difference represents approximately two litres of water.

If the clothes dry indoors, that moisture must leave through ventilation, be collected by a dehumidifier, or remain within the home’s air and materials.

Evaporation also takes heat from its surroundings. In a heated home, the heating system may replace some of that heat. Ventilation can carry heat outside as well.

That does not make indoor air drying a bad choice. It means zero electricity at the airer is not proof of zero household energy cost.

Condensation and Mould: Include the House in Your Calculation

Moist air can produce condensation when it meets sufficiently cold surfaces. Repeated moisture accumulation can contribute to mould.

Cornwall Council identifies drying clothes indoors without adequate airflow as a source of condensation and advises ventilation or dehumidification when indoor drying is necessary. Cornwall Council

For indoor air drying without a dehumidifier, use a suitable room with moisture extraction or ventilation, keeping the door closed to limit moisture spreading through the home. Avoid draping laundry over radiators. These approaches are reflected in council guidance. London Borough of Hounslow

Watch for persistent wet windows, musty smells and damp patches.

A humidity meter can help you spot changes, although one reading cannot tell you whether every cold corner is safe from condensation.

And do not assume laundry explains every damp problem. Leaks, building defects and inadequate ventilation may need investigation. Persistent mould deserves action, rather than simply another appliance purchase.

Run Your Own Great Autumn Laundry Experiment

You do not need to own every type of dryer. Start by measuring the method you already use.

Step 1: Choose a repeatable load

Use a similar selection and quantity of washing each time. A load of towels cannot fairly be compared with a few lightweight shirts.

Keep the wash programme and spin speed consistent.

Step 2: Decide what “dry” means

Use the same finishing point: for example, ready to fold and put away, including waistbands, pockets and seams.

Cheap but still damp is an unfinished result.

Step 3: Measure the whole drying period

Use built-in appliance monitoring or an appropriate energy monitor.

A plug-in meter must be suitable for the appliance’s load and permitted by its instructions. Do not use an unsuitable smart plug or extension lead to create a measurement setup.

A whole-home smart meter can offer an estimate, but other appliances switching on and off make the result less precise.

Step 4: Record more than the electricity

What to record	Why it matters
Load contents and approximate size	Makes comparisons fairer
Spin speed	Changes the starting moisture
Drying method and settings	Makes the result repeatable
Total kWh	Measures electricity consumed
Time until fully dry	Captures convenience
Room temperature and humidity	Helps explain indoor results
Extra heating, extraction or fan use	Reveals additional energy inputs
Condensation or damp smells	Checks the effect on the home

If outdoor drying needs a tumble-dryer finish, count that finishing energy.

Step 5: Repeat before drawing a firm conclusion

One load gives a useful starting point. Several comparable loads give a better picture.

A sunny, breezy afternoon and a still, damp evening are different drying conditions, even if both happen in October.

My View: Measure Before Buying Another “Money-Saving” Device

Having spent considerable time monitoring energy use at home, I find this sort of question much more interesting than a headline promising a miraculous saving.

The important distinction is between the power an appliance draws and the energy needed to complete a useful job.

“Low power” sounds reassuring. But the real question is: how much electricity did it take to get the washing dry?

I would also include convenience in the decision. Getting bedding dry before bedtime, keeping an airer out of a busy room, and avoiding persistent condensation all have value.

Going green should help us make better household decisions. It should not require pretending that everyone has a garden, a spacious utility room or the money for a new dryer.

The Best Answer May Be a Combination

For many households, the practical answer will change with the weather and the washing:

• Dry outside when conditions allow.
• Use an indoor airer with suitable moisture management for appropriate garments.
• Use a dehumidifier where it performs well and serves a useful purpose.
• Use a tumble dryer when predictable drying is needed, measuring its actual consumption.

If you have solar panels, daytime drying may reduce imported electricity. However, solar electricity still has value through export or other household uses. Stored electricity also has losses and an alternative use.

Whatever the tariff, follow dryer safety guidance: clean the filters, complete the programme including cooling, and avoid running it while asleep or away from home. electricalsafetyfirst.org.uk

Conclusion: Give Your Laundry a Meter Reading

The cheapest way to dry clothes cannot be established from the size of the plug, the length of the programme or a persuasive advert.

It depends on the load, the appliance, the weather, the room and what happens to the moisture.

Outdoor drying has a clear advantage in purchased energy. Indoors, a heat-pump dryer and a dehumidifier can be closer in running cost than their very different power ratings suggest. An unheated airer can be economical, provided the home can handle the moisture.

This week, measure the energy used to dry one load of washing.

Write down the cost, the time and whether the clothes are properly dry. Then look at the room as well as the laundry.

The most useful money-saving discovery may already be waiting in your own washing basket.