In winter and summer, a two-story home can have uneven heat distribution, with a hot upstairs and a cold downstairs. Heat rises, so excess heat collects in the second story, especially if you have a powerful air conditioning system on the first floor.
Of course, if you are uncomfortable on the second floor because it is too hot in the summer, you will be tempted to turn up the air conditioning to compensate. Unfortunately, this just makes the problem worse. The same goes in the winter; if you are too cold on the first floor you turn up the heat, only for the second floor to collect that excess heat.
Let’s take a look at some of the other major factors that can contribute to this issue:
Factor #1: Your Air Conditioner
Replacing your air conditioner is a major expense, but it is also an inevitability of home ownership as your system ages. The average lifespan of a central air conditioning unit is 15 to 20 years, and with every year of use, your system loses a little of its efficiency. If your air conditioner is primed for replacement and your second story is significantly hotter than your first, it could be that your system just can’t keep up with demand anymore. You should have a thorough inspection from a licensed HVAC technician to be sure, though, because there are other potential causes.
Factor #2: Your Ductwork
The core problem behind this temperature difference is usually the ductwork. Central air and central heating systems generate cold or hot air at the air conditioner or furnace. They push that cool or hot air through the home using a series of ducts, the square metal channels you might see running through your ceiling or walls.
However, the further the air travels through the ducts, the more it is affected by the surrounding temperature in the home. Cold air will get hotter as it reaches the second floor, lessening the impact of your air conditioning. The opposite problem happens in winter, as your furnace pushes heat through the ducts it is also propelled along by heat’s tendency to rise. You can get the heat to the second floor, but you can’t make some of it stay behind on the first floor. Smart changes in duct design are an option for some homeowners, but there is an even better solution.
Factor #3: Your Roof
In California, a poorly insulated roof could be the source of many of your problems. Our sweltering sun is here year round, and its heat may radiate through a thin roof, causing excess heat load. Add the heat your furnace is generating, and suddenly your second story is too warm.
You can fix this problem by installing new thermal insulation in your roof. However, not all homeowners will want to invest in this solution. A cheaper option is moving your thermostat. The second floor will always have a higher heat load, but thermostats are usually on a home’s first floor! Moving your thermostat up will have your furnace work only when the second floor is colder than you like.
7 Ways to Cool Down Your Second Floor
- Block the sun
Close blinds and shades to block light and UV rays. Be sure to seal all cracks, holes and gaps around windows to prevent air leaks. You might want to consider upgrading to more energy-efficient double pane windows.
- Insulate and ventilate
Add extra insulation to your roof and attic. You can even air seal your attic to prevent heat from seeping in. Also, adding an attic fan will help cool things down by circulating the air up there and decreasing the amount of hot air reaching your second floor.
- Reduce use of lights and appliances
Avoid generating additional heat upstairs. Keep the lights off or dimmed. Run clothes washers, dryers and dishwashers — all of which produce heat — during the cooler evening or morning hours. Even if appliances are located on lower floors, the heat will rise.
- Turn on the fans
Ceiling and floor fans do a great job of circulating the cold air that may be lingering near the floor. Just remember that fans cool people, not rooms. So if you are not going to be in the room for awhile, turn the fan off to limit energy use.
- Change air filters
Small things can make a big difference. A dirty filter can block the flow of cool air. But as a bonus, air filters can also reduce allergens.
- Adjust the fan setting on your thermostat
Switch it from “auto” to “on”, so the blower fan will run constantly and create a more even mix of air throughout your home. Running the fan does not use a lot of energy and actually may lower energy usage, because your HVAC system will not need to cycle as often.
- Consider adding an extra HVAC system
If you have tried everything and cannot get your upstairs to cool down, your home may be too large for your current system.