How to Cool the Upstairs of a 2 Story Home

If you’re like most homeowners, you want to keep your entire home cool during the summer months. But sometimes, the upstairs of your home is significantly warmer than the downstairs. And while you can just turn the thermostat lower, your downstairs might get too cold with the upstairs still remaining warm.

So, how do you get the temperature on your second floor as cool as your first floor? As a homeowner, there are several things you can do right now to get the second floor of your 2-story home cool and comfortable.

If you want to know why your upstairs gets hotter in the summer and how to fix it, keep reading this detailed guide!

a woman turning on the thermostat of her 2-story home

Why Does Upstairs Get Hotter In Summer?

The upstairs gets hotter in summer because the heat rises. When your air conditioner cools your downstairs area, the cooled air stays downstairs while the hot air from the rest of the home rises and fills the upper level of your home. This can make it feel like your air conditioner isn’t working as well as it should be, even though it may be working perfectly fine.

Besides heat rising, a handful of reasons might contribute to your upstairs being warmer than the rest of your house.

First Floor or Basement AC Unit

If your AC unit is located on the first floor or in the basement, cool air must travel further to reach the second floor. And, the farther the air travels, the less cool it will be by the time it reaches the upstairs. Plus, if your HVAC system isn’t balanced well, most of the cold air could be going to your first floor.

Single Zone Versus Multi-Zone Systems

a photo of a two-story home

Another potential reason for your upstairs being warmer than the downstairs is that you may have a single zone system while your home has more than one floor. In this case, the entire house shares the same thermostat (usually on the first floor) and cools or heats to the same temperature setpoint.

This means your thermostat may reach its setpoint of your desired temperature (for example, 68ºF), but your upstairs could still be several degrees warmer (perhaps 76ºF like my home).

On the other hand, a multi-zone system has multiple thermostats that can be set to different temperatures. This way, you can cool or heat each zone (or floor) to its preferred setpoint. So, if you want your first-floor cooler than your second-floor, a multi-zone system allows you to do that.

Radiant Heat Gain

a person using an infrared thermometer gun to check the temperature of a 2-story home

Another factor to consider is radiant heat gain. Radiant heat comes from the sun and enters your home through windows, doors, walls, ceilings, and the roof. The upper floors of your home are more likely to have radiant heat gain because they are closer to the sun (and your roof).

Note: In direct sunlight, your roof can reach over 150ºF on a summer day! This can make your upstairs hotter in the summer, even if your downstairs is cool.

Clogged or Leaky Ducts

If you have a central forced-air system, chances are your home has ductwork that carries the cooled or heated air to each room of your house. Over time, these ducts can become clogged with dust and debris or can develop leaks.

When this happens, the air traveling upstairs may be leaking into the attic or other parts of the house. This can make it seem like your AC system isn’t working as well as it should be because no cool air makes it to the second floor.

Old Air Conditioner

an old and rusty outdoor unit of an ac

If your air conditioner is over 15-20 years old, it may not be cooling as efficiently as it used to. This is because AC units tend to lose some of their cooling capacity as they age. So, if the upstairs is warmer than usual, get your AC unit checked out by an experienced HVAC technician. You might need a new one if it’s 15+ years old.

Undersized or Oversized AC Unit

Another potential problem is that your AC unit may be too small or too large for your home. If your AC unit is too small, it won’t be able to cool your entire house properly, especially on hot summer days.

On the other hand, if your AC unit is too big, it will cool your house too quickly and cycle on and off more often than it should. This lowers the lifespan of your AC unit, causes uneven temperatures in your home, and makes your HVAC less energy efficient.

Thermostat’s Set Point Isn’t Low Enough

If your second floor is warmer than the downstairs, ensure that your thermostat is set to a low temperature for your AC unit to turn on. The recommended set point for most homes in the summer is 78ºF.

If your thermostat is set any higher than this, your air conditioner will have difficulty keeping up, and the upstairs will be warmer than the downstairs.

Blocked Vents

an air duct filled with dust

If you have central forced-air, your vents and return air grilles play a vital role in your home’s cooling. The cooled air from your AC unit is pushed through the ductwork and comes out of the vents into each room of your house. Then, the warm air in each room is pulled back into the ductwork through the return air grilles and goes back to your AC unit to be cooled again.

If any of your vents or return air grilles are blocked, it can throw off this balance and make it difficult for your AC unit to cool your home properly. Make sure that all of your vents and return air grilles are clear,  unobstructed, and fully open so that the air can flow freely throughout your house.

How To Keep Upstairs Cool In Summer

Now that you know some of the potential causes of a warmer upstairs, here are several steps you can do to make it cooler.

Open All Return and Supply Vents

First, check all your vents and return air grilles to ensure they are open, unobstructed, and fully operational. This easy fix could make a big difference in your home’s cooling.

Increase Airflow Upstairs

If you have a central forced-air system, one way to improve airflow and cooling upstairs is to install an inline duct booster fan. This will help increase the flow of air through the ductwork and can make a big difference in the cooling of your upstairs.

Another way to increase airflow is to open any doors that lead from downstairs to the upstairs. This will allow the cool air from downstairs to flow into the warmer upstairs.

Clean Your Ductwork

a person dusting the air vent

Dirty ductwork can also restrict airflow to your second floor. Over time, it can get filled with dust and debris. Having your ductwork cleaned regularly (at least once every five years) ensures proper airflow.

Replace Your Air Filters

If your air filters are dirty, it can restrict airflow and make it difficult for your AC unit to cool your home properly. Replacing your air filters regularly will help keep the air flowing freely and improve the cooling of your upstairs.

Set Your HVAC Fan to “ON”

If your AC unit is having trouble keeping up with the demand, you can set the fan to “ON” instead of “AUTO” so it runs continuously. This will help circulate the cool air and keep your upstairs cooler.

Use Ceiling Fans

Ceiling fans are a great way to keep cool in the summer because they circulate the air in a room and make you feel cooler. If you don’t have ceiling fans upstairs, now is an excellent time to install them. Just make sure that you set them to spin counterclockwise so that they push the cool air down into the room.

Use Portable Fans

man in font of a portable fan

In addition to ceiling fans, you can also use portable fans to help circulate the air in a room and make you feel cooler. Place them in front of windows to help push the cool air into the room or in front of open doors to help circulate the air throughout your house.

Close Off Unused Rooms

If there are any rooms upstairs that you don’t use very often, close the doors to those rooms so that the cool air doesn’t escape. This will help keep the cool air focused in the rooms you use most often.

Add Insulation to Your Attic

If your upstairs is always warmer than the downstairs, it could be because heat is escaping through your attic. Adding insulation like rigid insulation or blow-in insulation to your attic is a great way to keep the heat out and the cool air in during the hot summer. This will help to keep your upstairs cooler in the summer and can also help you save money on your energy bills.

Install Vents in Your Attic

Since we’re talking about attics– if yours isn’t well-ventilated, it can cause your upstairs to be hotter than it should be. Installing vents in your attic will help to circulate the air and keep your upstairs cooler.

Close Your Curtains

a woman closing the curtains

Another way to keep a room cool is to close the curtains or blinds during the day. This will help to block out the sun and keep the room cooler. If you want to block as much heat as possible, opt for medium-colored curtains with white-plastic backings. A study shows that it can reduce heat gain by 33%.

Plant a Tree

If you have a second-story window that gets a lot of sun, you can plant a tree in front of it to help shade the window and keep the room cooler. Make sure you don’t plant the tree too close to the house since it could damage your foundation.

Invest In A Zone Control System

If you have a two-story home, the chances are your upstairs is warmer than the downstairs. One way to combat this problem is to install a zone control system in your ductwork. This will allow you to direct more cooled air from your AC unit to the upstairs, where it’s needed most.

Use a Dehumidifier

a woman turning on the dehumidifier

If you have a lot of humidity in your home, it can make it feel warmer than it actually is. A dehumidifier can help remove the excess moisture from the air and make your home feel more comfortable.

Make Sure Your AC Unit is the Right Size

If your home has a small AC unit, it will work harder to cool a larger space. It will use more electricity, and its components will work overtime to keep up with the cooling demands. So, ensure you have the right AC unit size for your home.

Upgrade Your HVAC Unit

If your AC unit is more than 15-20 years old, it might be time to upgrade to a newer, more efficient model. Newer AC units are much more efficient than older models and can make a big difference in cooling your second floor.

Get a Supplemental AC Unit

If you have a room that is always warmer than the rest of the house, you might consider getting a supplemental AC unit. Adding a window AC unit, portable air conditioner, or ductless mini-split will allow you to cool that one room without having to cool the entire house.

Conclusion

Your upstairs doesn’t have to be the hot spot of your home this summer. By following the tips above, you can keep your second floor cool and comfortable all season long. Let us know if you have other questions about cooling.

About The Author

Jonathon is a mechanical engineer with over ten years of experience in the HVAC industry. He has hands-on experience with all types of HVAC systems.

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