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Window AC vs Central Air

Figuring out the differences between different types of air conditioners is not easy. Every type of AC is installed differently and works best with different kinds of properties.

So how do you pick the perfect AC for your home? This article covers the differences between window AC and central air in detail. 

What’s the difference  between window AC and central air

The difference between window AC and central air is that window AC is a temporary air conditioner installed in an open window while central air is a cooling system that distributes cool air throughout your home via ducts. Central air is generally more powerful and more efficient than a window AC.

A window air conditioner is a single unit that you install in an open window. It is designed to cool a single room or a small one-bedroom apartment. 

Central air is an air conditioning system that can be fitted to cool very large buildings. The cooling mechanism is stored in one central location. The cold air it produces is then moved around your home via ducts. 

The big difference is that a window air conditioner can only cool the area near the unit. A central air system can cool many rooms using a single cooling apparatus. 

Cooling Capacity

Central air has a much higher cooling capacity than a window AC. A central air conditioner supplies 18,000 – 60,000 BTUs of cooling power while a window AC offers just 8,000 – 12,000.

A British Thermal Unit (BTU) is a measure of the cooling power of an air conditioner. A single BTU is the amount of thermal energy needed to change the temperature of a single kilogram of water by one degree Fahrenheit.

For reference, the 8,000 – 12,000 BTUs of cooling power offered by a window AC is enough to cool 350 – 550 square feet of indoor space. That’s about enough for a large single room or a small one-bedroom apartment.

The very smallest central air systems can beat that. An 18,000 BTU central air system can cool 700 – 1,000 square feet of indoor space, enough for an apartment with several rooms. There’s no real upper limit on central air systems, which often cool massive buildings.


Central air conditioning is much more expensive than a window AC. A window AC costs $200 – $600 while a central air system for a residential home costs $4,000 – $8,000. 

That’s a pretty monumental difference. It highlights how these two air conditioning systems are really for completely different use cases.

A central air system is a permanent solution to your air conditioning problems. It works with large properties and places a premium on effectiveness and efficiency. 

By contrast, a window air conditioner is designed to keep a small apartment cool. It works wells as a cost-effective air conditioner for rental properties. 

Energy efficiency

Central air is more efficient than window AC by a wide margin. In fact, central air is the most efficient kind of air conditioning on the market. Central air has an energy efficiency ratio (EER) of 18 – 21, much larger than the 10 – 13 typical of window AC units.

EER is a measure of how effectively an air conditioner uses its power. You can find an AC’s EEr by dividing its cooling capacity in BTUs by its power use in wattage. A higher EER means an air conditioenr is more effective. 

There are a few reasons why central air is more efficient than window AC. One is that a window AC is installed in an open window. As well as you can try and seal up the window AC, some heat is going to leak into your home along the sides of your window AC unit.

Should I buy a window AC or a central air?

You should buy a central air system over a window AC system if you need to keep a larger property cool. Window AC and central air systems are approaches to air conditioning designed for completely different properties. 

Central air is best at catering to large properties. A high level of energy efficiency will save you money in the long run if you have a lot of rooms to keep cool. That’s good because central air has very high upfront costs.

A window AC is better if you’re renting an apartment. The cooling capacity of this unit is enough to keep a one-bedroom cool during the hot summer months.

The low upfront costs also means that window ACs are viable to buy for just a couple of years if you plan to move in the future. You don’t need to modify the property to use one so there’s no need to convince your landlord to permit an installation.

Frequently Asked Questions (FAQs)

Q1: Can a window AC cool an entire house?

A1: Generally, a window AC is designed to cool a single room or a small space rather than an entire house. Its cooling capacity is limited compared to central air systems, making it ideal for apartments, single rooms, or small offices.

Q2: How much does it cost to run a central air system compared to a window AC?

A2: The cost of running a central air system is typically higher than that of a window AC due to its larger cooling capacity and the energy required to distribute cool air throughout the home. However, central air systems are more energy-efficient, which can translate to lower energy bills over time, especially in larger homes.

Q3: Can I install a window AC or central air system myself?

A3: Window AC units are generally designed for easy, DIY installation in a standard window frame. Central air systems, however, involve complex installation that includes ductwork, electrical wiring, and other components that usually require professional installation by a certified HVAC technician.

Q4: How often do I need to maintain my AC system?

A4: Maintenance frequency can vary based on the system and usage. For window ACs, it’s advisable to clean or replace the filter monthly during peak usage and check the unit for proper drainage. Central air systems typically require professional maintenance at least once a year to check the ductwork, thermostat, and refrigerant levels, among other things.

Q5: Is central air worth the investment for a small home?

A5: It depends on your cooling needs, budget, and future plans for your property. Central air can increase the value of your home and provide uniform cooling, but the initial investment and installation costs are significant. For small homes or those in milder climates, window AC units or alternative cooling methods might be more cost-effective.

Q6: How long do window AC units and central air systems last?

A6: With proper maintenance, window AC units can last around 10 years, while central air systems can last 15 to 20 years. Lifespan can be influenced by factors like usage patterns, maintenance practices, and environmental conditions.

Q7: Can central air improve indoor air quality?

A7: Yes, central air systems often come with advanced filtering options that can improve indoor air quality by removing dust, pollen, and other airborne particles. This is particularly beneficial for individuals with allergies or respiratory issues.