As air heats, the density decreases. Less dense air rises above colder more dense air. The temperature differences are more pronounced the greater the height of the column of air. As a result, two story homes are commonly cooler downstairs than they are upstairs. Increasing the air conditioning in the upstairs requires greater cooling of the downstairs, recirculation of air, reduction of heat sources in the upstairs area, removal of hot air and prevention of temperature transfer with the heat outside the home.
Turn the air conditioning temperature down. This forces greater volumes of cooler air higher in the air column of the home. The drawback to this method is the decrease in temperature at the lower level of the home. The air conditioner also may not be of sufficient tonnage to remove the heat from the home.
Circulate the air from the upstairs to the downstairs. When the air conditioning is not blowing the air, the transfer of warm air from the upstairs to the downstairs is limited. Set your air conditioner to run the fan continuously. This draws the warm air from the upstairs through the air return and circulates it through the rest of the house, leveling the temperature. Uses of ceiling fans, electric fans, and leaving doors open to increase circulation also have some effect.
Replace the air filter. Clogged filters prevent efficient air exchange through the home. Air conditioners work harder with clogged filters, raising electric bills with minimal impact on home cooling.
Reduce or eliminate heat sources in the upstairs. Cover windows with heavy blinds to prevent the entry of sunlight. Direct sunlight rapidly heats cool air. Turn off irons, curling irons and use cooler water temperatures when bathing and showering.
Turn on bathroom exhaust fans, and open the bathroom doors. Exhaust fans located on the ceiling, effectively remove the hottest portion of air from the room. The hot air collecting near the ceiling is pushed outside the home by the exhaust fan. Leaving the door open enables more hot air to be drawn into the room for exhausting. Installing an attic fan removes heat collected in the attic, allowing the insulation between the second floor ceiling and the attic to be more effective.
Increase the attic and wall insulation to prevent heat transfer from outside the home. Planting shade trees that shade walls or rooftops reduce direct radiant heat impacting upstairs temperatures.
Installation of dual zone air conditioning allows one zone, the upstairs, to be turned on, while the other zone remains off.
Do not close all the air registers on the bottom floor. Increased pressure may cause your air conditioners to freeze due to poor heat transfer.