Why the time you do your washing matters
Most people don't know that electricity has a peak and off-peak price - even on a standard tariff. The UK grid is busiest between 4pm and 7pm on weekdays, when millions of people arrive home from work, switch on the heating, and start cooking. During this window, electricity can cost 30 - 45p/kWh on a smart tariff.
After midnight, demand drops dramatically. Wind turbines keep spinning. Nuclear plants keep running. The result: electricity is often 5 to 10 times cheaper at 3am than it was at 6pm. Same grid. Same wires. Completely different price.
How much does a washing machine cost to run?
A standard UK washing machine uses approximately 1kWh per cycle on a 40°C wash.
| Time you run it | Typical price | Cost per cycle | Annual cost (7 washes/week) |
|---|---|---|---|
| 6pm peak | 32p/kWh | 32p | £116 |
| Midnight off-peak | 10p/kWh | 10p | £37 |
| 3am cheapest (Octopus Agile) | 4p/kWh | 4p | £15 |
Annual saving from switching evening to overnight: £79 - £101 from the washing machine alone.
Add the tumble dryer - which uses 2.5kWh per cycle - and the saving doubles.
How to set your delay start in 30 seconds
Almost all washing machines made in the last 8 years have a delay start function. Here's how to use it:
- Load the machine and add detergent as normal
- Find the Delay Start button - usually a clock icon or labelled "Delay" or "End Time"
- Set it to finish by 6am - if your cycle takes 1 hour, start at 5am
- Check AgileAlert to see tonight's exact cheapest window
- Press Start - the machine waits and runs automatically
Your clothes are clean when you wake up. You paid 4p instead of 32p.
Does temperature make a difference?
Yes - significantly. Washing at lower temperatures saves electricity on top of the timing saving:
| Temperature | Energy per cycle | Cost at 4p/kWh (overnight) |
|---|---|---|
| 90°C cotton | 2.0kWh | 8p |
| 60°C warm | 1.4kWh | 6p |
| 40°C standard | 1.0kWh | 4p |
| 30°C eco | 0.6kWh | 2p |
Modern bio detergents (Ariel, Persil) clean perfectly at 30°C for everyday loads. Combine overnight timing with 30°C washes and you're saving around £110/year from the washing machine alone.
What about the tumble dryer?
The tumble dryer costs even more - typically 2.5kWh per cycle. At 32p/kWh (peak): 80p per cycle. At 4p/kWh (overnight Agile): 10p per cycle.
Running your tumble dryer 4× a week at peak vs overnight: annual saving of £145.
The combined saving
| Appliance | Saving per cycle | Weekly uses | Annual saving |
|---|---|---|---|
| Washing machine | 26p | 7 | £95 |
| Tumble dryer | 70p | 4 | £145 |
| Total | £240/year |
That is £240 a year, from pressing the delay start button instead of the on button. Nothing else changes.
What if my machine doesn't have delay start?
A plug-in timer switch (£8 - 12 on Amazon) acts as a timer. Set it to turn on at 2am and the machine starts automatically. Only use this if your machine doesn't need manual input to begin - check your manual first.
See exactly when is cheapest tonight in your region
AgileAlert shows live half-hourly prices for all 14 UK regions. Colour-coded so you can see the cheapest window at a glance.
Check Live Prices - Free →Not on Octopus Agile yet?
On a flat-rate tariff the overnight saving is smaller but still real. The big wins come from smart tariffs like Octopus Agile where overnight prices fall to 3 - 6p/kWh. Switching is free, takes 5 minutes, and there are no exit fees.
Find out if Octopus Agile is available in your area →
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