The smart plug said 1.42 kWh, and I said a word in front of the washing machine that Alfie repeated at tea. That was how I found out that Cotton 60 costs more than twice what the Eco programme does. I'd been running towels on Cotton 60 ever since we bought the machine, three years ago, because that's what the label on the towels suggested and it seemed the safe thing to do.
How I measured
I bought a smart plug with energy monitoring for £8.99 on 25 April, checked that its rating was enough for a washing machine before I plugged one into it (read your own plug's label before you try this), and shuffled the Bosch out from under the counter to get at the socket behind it. Then for a fortnight I wrote down, after every load, the programme and the reading. It went in the back of the condensation diary notebook, next to the January bedroom humidity. Eighteen loads, 27 April to 10 May, priced at the 24.6p a unit we pay on the fix.
It was an ordinary fortnight, so it included a pair of football socks that had been in a school bag since Monday, a jumper with Mabel's fur welded to it and Rob's work uniform twice. I changed nothing about how we wash to do it, only what I wrote down.
The readings
- Eco 40-60: 0.64 kWh, 16p
- Cotton 40: 1.05 kWh, 26p
- Cotton 60: 1.42 kWh, 35p
- Synthetics 40: 0.58 kWh, 14p
- Quick 30: 0.32 kWh, 8p
- Rinse and spin: 0.12 kWh, 3p
I'd assumed the Eco programme, which takes just under four hours, would be the slow expensive one, and it turns out to be the cheapest of the proper washes. The numbers sit with the heating. The plug shows the machine pulling a steady 2 kW or so for the first quarter of an hour while the element warms the water, and that's most of the bill. The hotter the wash, the longer that first stretch goes on.
The Quick 30 is the cheapest at 8p, but Alfie's football socks needed it twice, which makes it 16p and a worse result than the Eco. On day six Alfie pulled the plug out mid-spin to watch the number 'go back to nought', so that reading is a guess and I did the sum for that load from the programme's average. I've been careful not to mention it to him since.
What a week of washing costs
Nine loads a week, eight on Eco and one on Cotton 60 for towels or bedding, comes to £1.63. Call it £1.60 a week, or about £83 a year in electricity. The detergent adds up to more than I'd have guessed. Aldi's non-bio liquid works out at about 9p a wash, which is 81p a week and £42 a year, so it's about a third of what a wash costs us all in. Water is unmetered here, so a load costs us nothing extra in that department.
For scale, Linda's old vented tumble dryer uses about 4.5 kWh a load, which is roughly £1.22 at our rate, so one load in hers costs more than seven Eco washes in mine. I'm not saying that to be smug. It's just good to see the whole row of numbers.
The thing I've changed is towels. They've moved from Cotton 60 to Cotton 40, which is 9p cheaper a load. That saves £4.68 a year, so I'm not claiming a triumph, but it's a change I can make without noticing, and I do like those. Bedding every other week still goes on 60. I haven't made a firm rule about it. I just stopped doing it out of habit.
It's mid-May, so the rotary line is out and the drying is free. In winter the airer or the dehumidifier would add 31p to 65p on top of each wash, which is why the cost of the machine is only half the story from October to March. But on a Wednesday in May with a full line, a basket of wet towels on the lawn and a breeze, the machine is the cheap bit of the whole business.
The plug is now in the drawer with the radiator key and the batteries. Rob wants to know what the shower costs. I've told him I'll put him on the list, after the kettle.
