In a two-story home it can be difficult to balance the temperatures between the upstairs and downstairs. As air gets hotter, it becomes less dense and rises. As it cools, it becomes more dense and sinks. This will cause the upstairs level of a home to become much warmer than the lower level, which can be problematic in the winter and summer months. Fortunately, there are techniques to help balance the temperature in your home and possibly save money on your heating and cooling bill.
Close air registers in the lower level of your home during the summer and upper level during the winter. This will force air from the air conditioning unit or furnace into areas of the home it won't normally reach. For example, closing registers in the upper level in the winter will force more warm air downstairs, but the warm air will naturally travel to the upper level of your home.
Turn on the fan setting of your home's thermostat. This will not run the furnace or air conditioning, but it will force the air inside your home to move constantly. This moving air will help keep the temperature in your home balanced.
Place fans around your home that will help keep air moving, like in Step 2. For example, in the summertime place a fan near the bottom of the stairs, pointing up. This will help push the cool air that has settled downstairs to your upper floor.
Insulate the attic and windows of your home if the temperature differences are problematic. Make sure heated or cooled air cannot escape anywhere, and consider replacing the windows if they are very old and leaky. This is especially important in the winter months when drafts can make a cold downstairs level feel even colder.