AC Not Cooling Upstairs? Here’s How to Cool the Upstairs of a 2 Story Home

Is the scorching summer heat not letting you get a good night’s sleep? Even worse, is your room on the second floor and your AC is not cooling upstairs?

A hot second floor is a common problem during the summers. You may have noticed that your air conditioner upstairs is not cooling as effectively as it is downstairs.

It can be really frustrating, especially when the temperature goes beyond 85F. However, there is no need to shift to the first floor yet. There are a lot of things you can do to keep your upstairs cool.

How Does Multi-Story House Design Affect Temperature?

Are you wondering why it is always hot upstairs and cold downstairs during the summers or why upstairs air conditioning is not doing an amazing job?

Unfortunately, physics is your enemy here!

Hot air is less dense than cold air, so it rises while cold air sinks. Therefore, cold air sinks to the first floor of a multi-story home while hot air rises to the second floor.

This also means that your air conditioner upstairs must work harder to maintain the optimal summer temperature for your home. Your HVAC system would be running all the time to achieve your desired setting. This will significantly increase your air conditioning bills and maintenance costs.

You may adjust your thermostat settings perfectly, but since cold air will eventually sink to the first floor, you will need to pay attention to several other factors.

Why Is AC Not Cooling Upstairs?

There can be many reasons why your air conditioning is working downstairs but not upstairs. Let’s take a look at them:

1. Single Air Conditioning System or Thermostat

If you don’t have a modern air conditioning system, your 2-story home may be relying on a single cooling system that depends on a single thermostat. Since this thermostat only senses the temperature for only one area of your home, it is very likely to leave warm spots in other areas.

This is especially the case if your thermostat is placed on the first floor. It will only kick on the cooling when this area becomes warm. However, the temperature is significantly different upstairs, and this setting will lead to a hot upstairs and cool downstairs.

2. HVAC Unit Is on the First Floor

Air conditioners have to push out hot air as well as introduce cold air to the second floor. Since central HVAC units are placed on the first floor, this requires double effort as cool air may continue to sink back to the first floor. As a result, your HVAC unit needs to push cold air up more frequently. This can easily overload your air conditioning unit and cause excessive wear.

3. Hot Roof

One of the main reasons the second floor gets too hot is an uninsulated roof. Your roof absorbs the sun’s heat, which then travels to the second floor, making it unbearably hot. This hot air can also travel down to the second floor through your attic.

Attic insulation is essential for a cool house and the effective working of your AC.

4. Faulty or Inadequate Ducts

If you have a ducted (central) HVAC system that is very old, then you may have outdated and inefficient ducts. They may have leaks or were improperly installed in the first place. You might also have too few ducts reaching the second floor.

5. Your HVAC Unit Is Cooling More Rooms Than Its Capacity

Another issue could be that your HVAC system is not compatible with your home. For example, it might only have the ability to cool a two-story, four-bedroom house. If you’ve added more rooms recently, it might be working overcapacity.

6. Your HVAC Unit Is Outdated

If you have been living in your house for quite some time and have never replaced the HVAC unit, it is possible that it has reached the end of its lifespan and can no longer keep upstairs cool in summer.

Read this article to learn about 8 ways to extend the average life of your AC.

7. The Temperature on Your Thermostat Is Too High

If you have a zoning system or multiple air conditioners installed, your second story might be too hot because you haven’t set the correct temperature. Most people set the same temperature for the upper and lower floors. Since hot air rises, this leads to a warmer second floor. You can quickly fix this problem by lowering the temperature of your second floor by at least two degrees. Smart thermostats, sensors, and zoning can significantly help in this regard.

Two-Story House Air Conditioning Tips

While the second floor is typically hotter due to several reasons mentioned above, the two-story house air conditioning tips will make your life easier and cooler. Here is to keep upstairs cool:

1. Increase Airflow to the Second Floor

You can increase airflow to the second floor by adjusting the HVAC dampers.

During summer, partially or fully close the dampers for the first-floor vents to force more air to the second-floor vents. If you cannot locate the dampers or your HVAC unit does not have them, you can close the registers on the first floor.

Read this article to learn more about fixing HVAC airflow problems.

2. Open Top Return Vents

Another option is to open the top return vents to draw in hot air from the top of your room and send it to the HVAC unit, which will keep upstairs cool.

3. Clean or Replace Your Air Filters

Dirty and clogged air filters restrict airflow and hamper the ability of your HVAC unit to keep upstairs cool in summer. Clean filters regularly and replace them after every 3-4 months.

4. Keep Your HVAC Fan Setting on “On” Instead of “Auto”

If the fan setting on your thermostat is on “auto,” change it to “on” to deal with the issue of AC not cooling upstairs. Turning the blower fan on will create an even mix of air throughout the house. 

When the fan is on “auto,” it only runs when actual cooling is taking place. However, when the fan is “on,” the fan continues to circulate air around your house, even if the cooling cycle is off.

5. Create Climate Zones

You can also create HVAC zones to set a different temperature for each part of your house. You can install separate thermostats or sensors for each zone for your central system. For ductless systems or mini-splits, use smart AC controllers like the Cielo Breez Plus. The number of zones will depend on the size of your house and cooling requirements.

Setting up multiple controllers for each zone will allow you to customize the temperature where required easily. Setting up climate zones can solve a hot upstairs and cold downstairs problem while greatly saving energy costs.

Learn more about dual-zone thermostats to set a different temperature for the first and second floors. It is done by using a system of dampers and sensors. This way, you can set your first floor and the second floor at different temperatures to create a comfortable climate throughout the house.

6. Upgrade Your HVAC Unit

The average lifespan of an air conditioner is around 10-15 years. If your HVAC unit is older than this, it might not be able to cool your house properly.

Another common issue is that many homes have an incorrect size of HVAC unit installed. You can consult a trusted HVAC specialist to see if you need to replace your HVAC unit or if it is too small to cool the second floor of the house.

Here is our guide for air conditioner sizing.

7. Invest in a Ductless Air Conditioner

If you are having trouble keeping your upstairs cool with your central air conditioner, you should consider investing in a ductless air conditioner.

These are self-contained units where each AC cools one room. There are many types of ductless air conditioners; mini-splits, portable air conditioners, and window units are some of the most popular choices.

It is easier to create climate zones with ductless ACs as there is a separate unit for each room. They are also more cost-efficient since you do not have to waste energy in cooling rooms you are not using.

Thermostats Settings for Each Level of Your Home

Considering you have multiple air conditioning units or multiple thermostats or sensors to effectively cool the various areas in your home, here are some tips for the perfect settings. With the best thermostat settings, you won’t only be able to cool the upstairs and downstairs effectively but also save energy.

A helpful tip is to set the second-floor thermostat at the temperature you want throughout your house. Then set the first-floor thermostat a few degrees lower. For instance, if you are most comfortable at 76F, set the second floor at 76 degrees and set the first floor at 78.

Since cold air sinks, the first floor will end up at the same temperature as the second floor. In most cases, doing so will effectively cool the upstairs of a two-story home and not take your bills through the roof!

78 F is the recommended daytime thermostat setting in summer. This setting ensures comfort along with energy savings. If you feel this setting may be too hot for your home, you can start by lowering the thermostat temperature gradually to help adjust. You can also maximize your savings by switching to a smart thermostat.

How to Keep Upstairs Cool Without AC?

Implementing the above-mentioned two-story house air conditioning tips will reduce your bills and help you figure out why your air conditioning is working downstairs but not upstairs.

However, if you don’t want to spend much on air conditioning and be more environmentally friendly, then don’t worry. It is possible to cool upstairs of your two-story home without spending a fortune on bills. Following are some of the ways to keep your upstairs cool without AC.

1. Insulate the Attic

One of the most essential two-story house air conditioning tips is insulating your attic. A well-insulated attic will reduce the amount of heat it absorbs from outside, thus reducing the heat transfer from the attic to your second floor, resulting in a cooler upstairs.

2. Ventilate the Attic

Another way to keep your upstairs cool is to ventilate the attic. A properly ventilated attic will push out hot air preventing the heat from reaching the lower floors. To ventilate the attic, you can install an attic fan to cool things down by improving air circulation.

3. Consider a White Roof

A light-colored roof will go a long way in solving problems related to hot upstairs and cold downstairs. During the summer, the roof absorbs heat which travels to your second floor. An intelligent solution is to paint your roof white, which will reflect the heat instead of absorbing it.

4. Block the Sun

Another way to beat the heat and cool your second floor is to close the blinds. Roughly 25-30% of residential heating and cooling energy use is due to heat gain and loss through windows. Therefore, keeping the blinds closed can significantly reduce AC costs and help to keep the upstairs cool in summer. For a more long-term solution, you can invest in window awnings and UV blocking window films.

5. Limit the Use of Appliances That Generate Too Much Heat

Using electrical appliances such as ovens will generate excessive amounts of heat, warming up your second floor even more. Instead, find suitable alternatives, such as grilling, and turn off any appliance that is not in use.

6. Replace Incandescent Lights With Compact Fluorescent Lamps

Incandescent bulbs emit a significant amount of heat and use up a lot of energy. Consider switching to compact fluorescent lights, especially if you struggle to keep upstairs cool. This will also reduce your energy costs.

7. Turn on Fans on the Second Floor to Increase Airflow

While fans may not reduce the temperature, they are much more cost-effective than HVAC units and help increase ventilation. The air from the fan also creates a cooling effect on your body.

It is best to use the fans in conjunction with your air conditioner. It would help if you run your fans counterclockwise in the summers to push air straight down and create a windchill effect. It’ll increase the airflow of the conditioned air.

Remember to clean your fans regularly. Dust on fans can overheat the motor, making them less efficient. Cleaning your fan can also reduce drag, improving its ability to circulate air. You can use a damp cloth to get rid of dust. For grease, an all-purpose cleaner sprayed on kitchen towels may work.

If your fan has loose screws, it might be unstable and shaky. This can reduce its ability to push air, making it work a lot harder than it should. Tightening or replacing loose screws will go a long way in improving your fan’s performance.

8. Turn on the Exhaust Fans

Bathroom and kitchen exhaust fans can make your upstairs air conditioner’s job a whole lot easier by removing hot air and allowing cold air to replace it. They also help reduce the high humidity in these areas.

9. Place Electric Fans In The Second-Floor Windows

If the windows on your second-floor open, place floor fans in them, facing outwards. This will help suck hot air out of your room. Electric fans are a good alternative if your exhaust fans are not working correctly.

10. Get Creative With Your Fan Placement

Experiment a little with your electric fan placement and try to create a cross breeze. Place one electric fan facing inwards, near a window that gets the most shade, to blow cool air into your house. Place another fan facing outwards, near a window on the opposite side, to push hot air out.

To make the upstairs cooler, place the outward-facing fans on your second floor, and the inward-facing fans on your first floor.

11. Heat-Proof Your Bed

If your room is on the second floor and you are having trouble falling asleep due to the heat, an excellent energy-saving tip is to heat-proof your bed.

Opt for bedsheets made of light, breathable materials such as cotton. You can also invest in cooling mattress pads that absorb heat.

12. Retreat to the Basement or First Floor During Peak Summer Days

If all else fails, you can take advantage of the fact that cold air sinks and shift to the first floor or the basement (if you have one). You’ll feel a notable difference and feel much comfortable.

However, that is the last resort. There is a lot you can do to cool upstairs of a two-story home.

A chilly second-floor may seem like a distant dream during the height of summers. However, armed with these tips, you will undoubtedly be able to relax and escape the summer heat.