This will allow the unit to operate only if the temperature exceeds the limit set. It takes more energy to start the unit after it's been turned off then leaving it set. Just don't forget to turn it back on when you get home. When someone in the family leaves the room and doesn't turn off the lights, have them place a quarter in a jar. Use your dishwasher verses cleaning a load of dishes by hand.
Dishwashers use less hot water and less energy.
In addition the dishwasher is more sanitary. Remember it is more efficient to wash a full load. Save energy during warm weather. Hang your clothes out to dry instead of using the dryer. Instead of preheating and then placing food into the oven, place the food in when you start the oven.