A motorized window treatment to automatically control the position of a covering material in front of a window to save energy. The motorized window treatment has an eco-mode whereby to at least one climate characteristic is measured by a sensor to save energy by decreasing the load on a heating and/or cooling system of the room in which the motorized window treatment is installed. The motorized window treatment opens the covering material on sunny winter days to allow energy from sunlight to be stored in the mass of the room, and closes the covering material at night to insulate the room and allow the energy from the sunlight stored in the mass of the room to heat the room and reduce the load on the heating and cooling system at night.