I assume they mean washing the clothes in cold water instead of hot. changing the washer’s settings does cunningly mask that the wash will also be less effectiv

I assume they mean washing the clothes in cold water instead of hot. changing the washer’s settings does cunningly mask that the wash will also be less effective. Numbers: A top loading machine[3] uses about 150 liters (40 gallons) of water to fill. If you fill that with hot water that is water that has had 30°C (50°F)[1] added to it. That is about 20 megajoules (5kWhr). Heating a liter of water from room temperature to vaporization[2] takes 2.5 megajoules (700 watt hours). So… in very rough numbers you can vaporize 8 liters of room temperature water for the same energy it takes to fill a top loading washer once with hot water. I'd say my load of wash doesn't lose 16kg being dried, so I presume less than 8 liters are being vaporized. [1] I'm pulling numbers out of google here, you didn't expect more than one significant digit, did you? [2] Vaporization is more than 5 times the energy from 1°C to 99°C. [3] Terribly inefficient way to wash clothes, but if an article is going to make dramatic statements, you have to figure they will pick the most extreme numbers.