Air Conditioning Vs Open Windows At Night: Which Is Best?

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Some people might like breathing fresh air at night while indoors. Others may want to run their air conditioners throughout the night. So which is better, using the AC or keeping the windows open? We researched and asked different experts to give you this answer.

Property owners should assess their living spaces to check if using air conditioners or opening windows is better for them at night.

For example, some homes may find it better to open windows at night to help reduce electricity costs. On the other hand, using the AC may help keep harmful allergens outside.

Take note that both options have unique pros and cons. Continue reading as we talk about the advantages and shortcomings of running the AC and opening windows at night in greater detail.

Nicely decorated house at night, Air Conditioning Vs Open Windows At Night: Which Is Best?

Is Fresh Air Better Than Air Conditioning At Night?

The answer boils down to specific situations. Some properties may gain more advantages by running their air conditioners. On the other hand, some homeowners may find it more pleasing to breathe fresh air through their open windows at night.

This means that there’s no "one size fits all" answer to the debate between using the air conditioner and opening the windows at night. Still, it’s important to note the pros and cons of both options to help you decide which choice suits your living environment.

Pros of Using the Air Conditioner at Night

Air conditioner (ac) wall mount or indoor unit in room.

Keep Allergens at Bay

Using the air conditioner may help individuals with seasonal allergies sleep at night peacefully.

Many air-conditioner filters, like the ones below, help prevent outside allergens from entering the home. These appliances may also help lower indoor humidity. Sleeping in a humid room may increase the risks of health issues because of bacteria and mold growth.

Check out these anti-allergy filters on Amazon.

Still, it’s important to ensure that the air conditioner filter won’t encounter heavy dirt and dust buildup.

To learn more about this topic, check out our article:

Do Central Air Conditioners Have Filters? [And How to Maintain Them]

Consistent Indoor Climate

Air conditioners typically allow users to adjust their preferred settings manually. These appliances will then stay at the set temperature levels until changed.

Many units can also adjust their temperature settings automatically. Most models do a reasonably good job of providing consistent performance throughout their running times.

This consistency can be ideal for fairly light sleepers that may wake up because of sudden shifts in climate. So using the air conditioner at night might also help improve sleep, reducing the risks of health problems like concentration and memory impairments.

Cons of Using the Air Conditioner at Night

Increased Energy Costs

Air conditioners require electricity to run. Because of this, households following relatively strict budgets will see an increase in their monthly energy bills if they use their air conditioner at night.

Take note that running costs for air conditioners generally fall within the $0.06 to $0.88 per hour range. If a user keeps this appliance running for an entire 8-hour sleeping session, it’ll result in a $0.48 to $7.04 increase per night.

That can also mean an increase of about $14.40 to $211.20 in electricity expenses per month if users turn on their ACs every night.

Frequent Maintenance

Energy.gov recommends that homeowners clean their air conditioner filters at least once per month. But using the appliance may demand more frequent care and maintenance than average.

Failure to keep up with this routine may increase the risk of users contracting health problems, particularly respiratory issues.

Pros of Opening the Windows at Night

Gorgeous view of sunset trough open window. Sweden.

Reduced Carbon Dioxide Levels

A study published in the Indoor Air publication found that people often found it more comfortable to sleep with their windows open than in unventilated rooms. The researchers attributed the results to the decrease in carbon dioxide (CO2) levels and improved airflow.

Take note that high exposure to CO2 can lead to certain health complications, such as dizziness and restlessness. If left unchecked, the risks can increase to serious problems like asphyxia and an increase in blood pressure.

Enhanced Concentration

People who sleep while breathing fresh air may find themselves having more focus during the day than resting in closed rooms. Again, this phenomenon might be thanks to the reduced carbon dioxide levels for significant quantities of the compound may reduce brain functions for the next day.

Free of Charge

Windows are typically a requirement for most homes, unlike installing and using air conditioners. Remember that switching on ACs will demand extra energy costs. On the other hand, opening a window won’t cost homeowners a cent.

Cons of Opening the Windows at Night

Attracts Pests

Opening the window at night can be an open invitation for pests like bees, cockroaches, and rodents to enter sleeping quarters. Homeowners may buy and install windows screens, like these below, to help reduce the risks of critters and insects entering their homes through open windows.

Check out this magnetic window screen on Amazon.

Increased Dirt and Dust Buildup

Dirt and dust are lightweight substances that can easily enter homes through open windows. These airborne particulates can build up in sleeping areas, which may increase the risks of respiratory problems for sleepers.

Is It Bad To Run Your AC With Windows Open?

It’s generally not a good idea to keep the windows open while the air conditioner is running. Doing so will result in irregular cooling since hot air might also be blowing into the room through the open window.

That scenario can also lead to a skyrocket in the home’s energy bill. Users may need to compensate for the reduced cooling efficiency by turning up the power used on the AC.

Still, some households may find their electricity bills to increase even if they’re using their air conditioners with windows closed.

If you find your window AC has a gap, be sure to read our guide:

How to Cover the Space Above a Window Air Conditioner

Does AC Help Air Quality?

Air conditioners may help improve air quality. But each AC unit’s ability to prevent unwanted airborne particulates from entering rooms is different. Interested buyers should look into the Minimum Efficiency Reporting Value (MERV) of each cooling system they plan on buying.

MERV coefficients range from 1 to 20. Also, take note that a high MERV rating typically means that the AC’s filter does a great job at trapping particles. Air conditioners with a 13 MERV rating can help block harmful bacteria and viruses from entering homes.

Check out this MERV 13 AC air filter on Amazon.

How Can I Increase Ventilation In My House?

Man's hands removing air duct cover from ceiling

Aside from opening windows and using quality air conditioners, other solutions that can help improve airflow in a house are:

Use a HEPA Cleaner

Portable high-efficiency particulate air (HEPA) cleaners can help filter dust and other airborne substances from entering in and spreading around homes. Some high-quality models may also have the ability to block certain gases.

Buyers should pay attention to the minimum clean air delivery rate (CADR) of their preferred HEPA cleaning units. It’s because the CADR should match the size of the room where the cleaner will run.

Here’s a list of some room sizes and their minimum CADR requirements:

  • 100 square feet: 65 cubic feet per minute
  • 200 square feet: 130 cubic feet per minute
  • 300 square feet: 195 cubic feet per minute
  • 400 square feet: 260 cubic feet per minute
  • 500 square feet: 325 cubic feet per minute

Check out this air purifier with HEPA cleaner on Amazon.

Install an Exhaust Fan

Exhaust fans are appliances generally installed in bathrooms or kitchens to help improve airflow in those rooms. Different types are available on the market to fit specific space requirements. Some model classifications of exhaust fans are:

  • Standard
  • Decorative
  • In-line

Like buying a HEPA cleaner, it's important to purchase and install an exhaust fan of the appropriate size. The general rule of thumb is to attach a fan that provides 1 cubic foot per minute of airflow to 1 square foot of the room’s area.

For example, a 100 square foot room kitchen should use an exhaust fan that can provide 100 cubic feet per minute of airflow. It’s also a good idea to use a slightly oversized fan to help supply the room with enhanced ventilation.

You can also watch the video below for instructions on how to install a through-the-wall exhaust fan:

Final Words

Using the air conditioner at night might be an excellent choice for some homes. But some properties in certain locales might do better with sleeping with their windows open. Make sure to assess your living conditions while looking at the pros and cons of these options to know which choice best fits your sleeping environment.

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