What’s best for laundry? Hot or cold water?

Environmentally speaking, the best thing is to use cold water, in order to save energy. However, in detergency lukewarm is better than cold water. Why?

First of all, dirt is better solubilized with increasing temperature values, as in most aqueous solutions… just think about sugar into coffe: it is better to add it as long as coffee is hot, so it will be dissolved earlier!

In detergency there are specific parameters about temperature. For example, some surfactants (ingredients acting on surface tension) work well at 25°C (77°F), others are optimized at higher temperatures.

Also very ecologic detergents need at least 25°-30°C (77°-86°F) to wash well, higher temperatures than ones of waterworks (5°-10°C, 41°-50°F) in winter.