If you do not have an Energy Star washing machine (meaning one that is energy efficient), you would probably be surprised to know that you could be throwing money away by washing your clothes in hot water. This is because most of the electricity used on older model washing machines is the hot water itself!
If you have an older machine (common if you are a renter), consider using one of the specially formulated cold water washing detergents. This laundry detergent is especially designed for use with cold water, so it is designed to get your clothes just as clean as if you used regular detergent and hot or warm water.
Not sure if your washing machine is energy effecient? If you don’t see an energy star label, look on the back to get the make and model of it and you can do a search for it on the internet to see what information you can get about whether it is energy effecient or not.