Well, this one is pretty self-explanatory. Turn the dial down to 30°C.
The washing powder
Modern detergents are designed to work perfectly at 30°C, so unless you've been rolling around in the mud or have been eating like a complete mucky-pup, then your clothes should emerge as fresh and clean as ever.
The Ethical Superstore are a pretty friendly bunch who have some great offers on all sorts of household goods - including some nice eco friendly washing powder and free fabric conditioner, helping to keep clothes cleaner at a lower temperature.
The washing machine
Perhaps you have a pretty old washing machine that doesn't have a 30°C setting? If that's the case then it's probably time to upgrade to an AAA rated machine.
There are a few other laundry-related good deeds you can do while you're at it: