TL:DR - wash at 20 degrees, save a packet. If you are already doing this, my apologies; posting in the hope that some people don’t realise how much of a difference it could make.
For about 5 years, I have been turning the temperature on my washing machine down from the default of 40 to 30. The washing still seemed clean, I assumed it would save me money and be good for the planet.
Just recently I have become intensely interested in how much electricity things use, trying to reduce unnecessary usage and move as much as possible times when it’s cheaper. So I have got used to how much various appliances use, e.g. using the oven and hob to cook a meal will use about 1.5kWh, the dishwasher and washing machine both use about 1kWh per cycle. My solar system has monitoring which means I can see the power being used every 5 minutes.
Then one day I looked at the 20 degree option on the washing machine and thought I would give it a go.
The result….. I can barely see the energy being used by a washing machine cycle. It used to draw about 2kW for 10-15 minutes. Now the heating cycle doesn’t even last long enough to get picked up by the 5 minute monitoring. Spin seems to use about 700W but only for a few minutes.
So instead of using 1kWh per cycle, it’s using about a quarter of that. So if you’re on the standard variable tariff of about 28p/kWh, that would save you 21p every time you put the machine on. If, as some forecaster are suggesting, electricity goes up to 40p/kWh in October, you would then save 30p per cycle.
Multiply that by the number of times your machine goes on per week, it will add up to quite a few pounds every month, which for many people these days could be significant.
Hope this helps someone.