Best Air Conditioners of 2024, From Mini-Splits to Central HVAC Units

As most of us are aware, the Earth continues to get warmer; summers are longer and hotter and likely to become even warmer. In most areas, keeping indoor spaces cool and comfortable requires the use of air conditioning. As well as keeping us cool, air conditioning, when installed and used correctly also helps mitigate ambient household air pollution.

To help end this worldwide health epidemic caused by poor air quality and toxic indoor environments, Michael Rubino, a mold and air quality expert and environmental wellness advocate founded a company called HomeCleanse. I consulted him, as well as Traci Fournier, VP of Operations at One Hour Heating & Air Conditioning and Glenn Wiseman, RASDT, RHDT, at Top Hat Home Comfort Services about all things air conditioning to put together this guide for choosing the best window air conditioner, central HVAC unit, mini-split or portable model for a range of individual needs and spaces.

Our picks for best air conditioners

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The U-shaped design of this Midea air conditioner means it installs over your window ledge, allowing normal operation of your window on days that don’t warrant an AC—or whenever you need to let some fresh air inside (you know, when you accidentally burn something in the oven).

Both app and voice control options make controlling the Midea easy and the long-distance air flow reaches 20 feet. And, it received a 2024 energy efficient certification from ENERGY STAR.

Specifications:

• Cooling area: 550 square feet
• Cooling capacity: 12,000 BTU
• CEER: 16
• Dimensions: 21.9” W x 19.17” D x 13.26” H
• Type: Window
• Price on publish: $499

The bottom line:

Incredibly quiet, smart AC unit with U-shaped installation and Energy Star most efficient rating.

Get it here: Midea U-Shaped 12,000 BTU Air Conditioner

What to consider when choosing air conditioners

Cooling capability/size

“When units are oversized or undersized, they can lead to severe complications such as high humidity, temperature swings that create condensation, and poor airflow,” said Rubino. For central systems, this can even compromise the pressure of the building, creating a negative interior pressure that pulls in moisture from the outdoors, he explained.

HVAC technicians use something called the Manual J calculation to help them decide the best-sized air conditioner for a specific space. “The key to this calculation is working with accurate information,” said Fournier.

For a central system, they take precise measurements throughout the home, often conducting tests to assess the efficiency of insulation and the quality of door and window seals, she explained.

When choosing a window AC or portable unit, pick one with a BTU measurement for the size of the room you intend to install it in. The general calculation for that is square footage multiplied by 20 BTUs which will give you a measurement in the 1000s. For instance, if your room is 300 square feet, multiply by 20 for 6,000. This means you should look for a 6,000 BTU air conditioner.

Features

“Air quality is an important feature for AC systems. This can include ultraviolet light treatment to kill bacteria in the air as well as air filters,” said Mark Collins, CEO at 1-800-Plumber + Air.

“For central AC units a programmable thermostat helps your system adjust to the environment and maintain temperature consistency,” said Wiseman. He suggests changing the temperature by a few degrees while you are at work or sleeping, which contributes to overall savings.

Air conditioners that feature a dehumidify setting are useful if you live in a region with consistently high outdoor humidity.

Consider smart connectivity so you can control the temperature of your home remotely from your smart device no matter where you are.

Energy efficiency

How much direct sunlight your home receives as well as the number of doors and windows influence the efficiency of your air conditioning unit. A ceiling fan (or two) will also help circulate the air in your home, making it feel cooler.

Air conditioners receive an energy efficiency identifier measured in a SEER (Seasonal Energy Efficiency Ratio). The higher the number, the more efficient it is. Look for units that have an ENERGY STAR award as well as a high SEER number.

Window versus portable versus central versus split

Window air conditioner units offer easy installation that most homeowners can accomplish on their own. They’re also often the best option for renters, apartments, or co-op buildings that have a plethora of restrictions and rules to follow when it comes to renovations.

Portable air conditioner units are even easier to install (you just need to vent the hose out of a window) and can be shuffled from one room to another when needed. Wiseman recommends purchasing an extra vent kit if you go with a portable model.

“That way, you can move the unit to multiple rooms and focus on setting up the hose(s) and not messing around with the vent. This will make your life a lot easier,” he explained. I, for one, am always for anything that will make life a bit easier, especially when it comes to air conditioning.

For rooms without windows or in homes that do not have duct space between floors (making a central unit installation challenging), mini-split systems offer an economical and helpful choice, said Wiseman. Many hotels use mini-split units in their rooms. In most instances, you should enlist an HVAC technician to install one of these.

As well as being more energy efficient in the long run, a central air conditioning system provides more air filtration, Rubino told me. “For example, a mini-split does not allow you to upgrade to a higher MERV-rated filter, leaving you stuck with the standard filter that comes with the unit,” he explained, “This means you must be more diligent about cleaning the unit regularly (quarterly instead of semi-annually) because particles like mold and bacteria are too small to be filtered out entirely which allows microbial growth over time.

Which kind is best for you depends a lot on the nature of your home. If you have the budget and own your home, a central air conditioning unit can be a great investment and lower your energy bills for years to come.

Manufacturer

“Making a significant purchase for any home appliance should be heavily researched,” said Rubino. (Which is why I’m writing this guide!) When comparing manufacturers and air conditioner brands, consider how easy it is to maintain and find replacement parts as well as the length and scope of the warranty. Read reviews for that specific unit from the manufacturer.

How we selected the best air conditioners

To select these air conditioners I researched companies, scoured online reviews, and conducted consultations with professional experts in the HVAC industry. I took into consideration reliability, available features, cost, and warranty information to compile this guide of the best options for a variety of situations (and budgets).

Frequently asked questions (FAQs)

How do you know how big of an AC unit you need?

Generally, take the total square footage of the space you intend to air condition and multiply that by 20. This will give you a BTU measurement in the 1000s.

For central units, professional technicians use something called the Manual J calculation, Fournier told me. This includes the square footage of the home or facility, its geographical location and directional orientation, an evaluation and rating of the insulation, the number of windows and doors plus their energy efficiency and directional orientation and the number of occupants.

The detailed calculation breaks down like this:

• (Square footage) x (ceiling height) x 20 BTUs
• (Number of occupants) x 100 BTU
• (Number of entry doors) x 1,000 BTU
• (Number of windows) x 1,000 BTU

“By adding the total number of BTUs from all of these equations, your technician will have the total AC unit load required for your home,” explained Fournier.

Is it cheaper to run window units or central air?

“While a central air conditioning unit is initially more expensive than window or portable units—because of the high installation costs—it pays for itself over time by saving you on energy costs,” said Wiseman.

Central AC units are also more efficient than window ones because they cool the entire house instead of just one room at a time, explained Wiseman. They use less electricity because they don't need to run as often when the weather gets warm outside.

“Some central air conditioners come with a variable-capacity operation that allows them to adjust their output based on how much cooling your house needs during different times of the year. If you do routine maintenance on them, they can be very inexpensive to keep up over a long period of time,” said Wiseman.

Which is better: window type or split type?

Usually, mini-split systems are more economical and can be helpful replacements for rooms that do not have windows, said Wiseman. Designed to mount high on the wall, a mini-split system helps circulate air evenly throughout the room. These are the kind of systems you find in many hotel rooms.

“They need to be installed on an outdoor wall in order to connect the refrigerant and condensate drain lines of the unit to an outdoor compressor and condenser,” said Wiseman. Most people enlist the help of an HVAC technician to ensure proper installation.

Window units, on the other hand, are self-contained and can be installed by homeowners. They’re a great solution for many homes, though ultimately a split system will likely be more energy efficient. If you rent or own an apartment in a prewar co-op building with all kinds of rules and restrictions (like me) a window air conditioning unit is probably your best solution.

How can I increase the efficiency of my AC unit?

“Start with simple steps like sealing any drafty areas and making sure your insulation is up to par,” said Fournier. And, when it’s time to upgrade, purchase models that are ENERGY STAR certified to meet strict efficiency standards.

Other tips from Fournier include: use energy-efficient light bulbs like compact fluorescents or LEDs and upgrade your windows to double or even triple-pane models to keep the heat in and the cold out.

How can consumers ensure their system stays clean and mold-free?

Rubino suggests having a service provider well-versed in environmental contaminants perform regular maintenance. To find a technician that fits that bill, look for those with NADCA certification.

If you have a centralized system, clean it twice yearly (usually in spring and fall). If you have a PTAC system, window AC units, or mini splits, clean it at least once every quarter.

“Since microbial growth can happen inside the evaporator coil, the blower wheel, and the ductwork, it's important that the cleaning is thorough!” he said.

What are some options for retrofitting a central AC unit into a 2-story house which does not have duct space between floors?

To be adequately efficient, central AC units require ductwork throughout the entire home.

“If you have the ductwork already on the main floor, your options would be to renovate to have it installed through the remainder of the home, or supplement on the upper floors with either window units or a ductless system,” said Wiseman.

Ductless, or mini split systems will be most effective for rooms with outdoor-facing walls that do not have windows, he said. They’re much less expensive than installing the necessary ductwork throughout the entire home.

Another option is to use the existing ductwork for a high-velocity AC system, said Wiseman. More powerful than traditional HVAC systems, these “run air through flexible tubes that are much smaller than traditional ductwork, which can retrofit into your home's structures with minimal construction.”

These high-velocity systems push air at much higher rates making them more energy efficient as the system does not need to stay on for long to achieve the desired level of coolness (something I think we all strive for, at least some of the time).