Keep the air moving by turning on the fan setting of your home's thermostat. Turn the fan from “auto” to “on”. The fan will circulate the air continually throughout the home and can help even out temperatures between floors.
The general rule of thumb for a two-story home is that you should set each thermostat two degrees Fahrenheit apart from the other. During the summer, when your AC is running, set the upper floor at the temperature you actually want in your home. Then set each floor underneath that to two degrees warmer.
Add a zoning system
In addition to helping you balance the temperature on different floors, a zoned system can allows you to heat or cool individual rooms on demand, or close off unused rooms entirely.
Upper stories are warmer than lower ones, so you want to adjust the temperature depending on the season to properly set up upstairs and downstairs thermostats. During the summer, set your upstairs thermostat to your desired temperature, and the downstairs unit two degrees warmer.
Blame physics: hot air rises while cold air sinks. That means your upstairs typically gets hotter than your lower levels, even if your air conditioner's working in overdrive. Your roof's hot, too: Unless you have shady tree cover, your roof absorbs a ton of heat from the sun.
The downstairs thermostat should be set to your ideal temperature, and the upstairs thermostat should be about 2 degrees cooler. The heat should be balanced pretty well with this method, and your downstairs will get a little bit extra warmth to keep you comfortable.
The startup process for a furnace consumes more energy than simply running the entire time at one set temperature, costing you additional money. To maximize efficiency, it's best to keep your furnace (or AC) at the same consistent temperature for long periods of time.
If the first floor of your home is colder in the winter months, keep the dampers on the first-floor vents fully open and only partially open the vents on the second floor to force more of the warm air to enter the first-floor areas.
Setting both your upstairs and downstairs thermostats to the same temperature usually doesn't resolve this problem. Instead, during the hot summer months, turn your upstairs thermostat to your target temperature and your downstairs setting to two degrees warmer for optimal comfort and efficiency.
In the short term, yes. By closing your vents intermittently, you can save money on bills throughout the hottest months of the year. That said, you'll want to rotate which vents you have closed to avoid air blockages and vent damage. You should also never leave a vent closed for more than two days at a time.
One of the biggest reasons the upstairs gets so hot is that the current sealing, insulation, and ventilation systems are not working correctly. On the sealing side of things, gaps in the home's structure can go unnoticed and quickly add up, causing air conditioning to be wasted.
If you have window units, and you primarily stay in the lower level of your home, there is nothing wrong with turning the AC off upstairs. Heat rises, so turning off the AC on the upper floor (or floors) will not affect your comfort level downstairs, nor will it affect how much the units downstairs have to work.
For winter, the ideal thermostat temperature is 68 degrees Fahrenheit when you're at home. Energy.gov 68 degrees is a good room temperature while you're awake at home, but recommends lowering it while you're asleep or away. Lowering your thermostat 10-15 degrees for eight hours can reduce your heating bill by 5-15%.
Poor air flow, bad sensors, or other broken components can also cause room temperatures to be different than your thermostat setting. The biggest clue that your furnace is the culprit is your heating bill.
Winter Thermostat Settings
You will want to take the opposite approach in the winter. Set the first floor's thermostat to your desired temperature, and then decrease the temperature setting on your thermostats by two degrees as you go up. Warm air on the first floor will rise and make the upper floors more comfortable.
If there is a cold room in your house, the problem has likely been caused by dirty vents, cracked ductwork, worn insulation or faint drafts.
The air that flows out of your vent should be 16 to 22 degrees Fahrenheit cooler than the air that flows back into it. The method commonly used to measure the air temperature coming out of your vent is known as 'Delta T'.
Set your thermostat to 68 degrees Fahrenheit in the winter
According to ENERGY STAR, setting your thermostat to 68 degrees Fahrenheit (20 degrees Celsius) when you're home is the ideal balance of comfort and energy efficiency.
For every degree that you lower the thermostat can help you save up to 1% on your heating costs. So, if you turn down the heating eight degrees for about eight hours a night, you can enjoy a saving of approximately $180 annually on your heating.