Did you know that 3/4 the energy use and greenhouse gas emissions of doing laundry come from heating the water? All you have to do is use cold- perhaps with a detergent designed for cold water- and you can save that energy. Unfortunately people don't care- they're used to using hot and they won't be told differently.
It also reminds me of a story. A student last year told about when her parents bought a new, energy-efficient washing machine. She wanted to save energy, so she drove out to her parents' house to use the machine. She hadn't thought about the fact that driving out there would use up at least as much energy as she saved by using the efficient machine. That's what economics is about: recognizing how all the pieces fit together and using that information to make better decisions.