Cooling a New Addition In the Pacific Northwest: Window AC vs. Ductless AC

Summer is a great time to add a new addition to your home. Life slows down and you have plenty of time for projects before the weather starts to turn in the fall. Whether you’re adding a sunroom or a spare bedroom to your home, it involves a lot of research and planning to determine the best style, structure, and fit for your lifestyle. From electricity to materials, there are a lot of choices to consider throughout the project. That’s why we’ve created this guide to help you determine the best cooling option for your new addition. Here’s a full comparison between window AC vs. ductless AC to cool a new addition. 

Window AC vs. Ductless AC

When cooling a new addition, window AC and ductless systems are often two viable options. 

A ductless mini-split is an efficient, eco-friendly, versatile heating and cooling system that allows homeowners to control the temperature of an individual room or space, or even cool a whole-home. It’s a great system for new additions, as it doesn’t require costly, complicated ductwork as central air conditioning systems do. 

A window AC unit is another cooling system option that traditionally cools one room at a time. It’s a common solution to cool a new addition to a home. So which is better for your new addition? Here’s a full comparison. 

System and Installation Cost

The cost between a window AC vs ductless AC is quite significant. Window ACs tend to be a short term solution, whereas ductless systems are long term and provide cost savings over time. A window AC unit itself typically costs between $150-750, depending on the size of the space that requires it and the model you choose. The installation of the unit varies, depending on the provider, but typically runs between $200-$1,000. 

The average cost of installing a ductless system with a single indoor heating/cooling zone starts at about $8,000. This cost includes:

  • Equipment
  • Parts
  • Expert installation services
  • Associated electrical work
  • Permits

With less required maintenance and increased energy efficiency, ductless systems are cheaper to upkeep and less expensive to operate than a window unit over time.

Verdict: A window air conditioning system is cheaper initially, but they come with downsides that sophisticated units don’t. A ductless system offers greater benefits and even savings over time, making them the ideal investment if your budget allows for a longer-term investment.


Installing a window air conditioning unit is fairly simple. You can do it on your own with only thirty minutes and a second pair of hands.

A ductless professional should handle the installation of a ductless system due to the handling of electrical and refrigerant lines. However, it’s still a fairly simple process for a ductless contractor. With only a 3-inch hole to connect the indoor air handler to the outdoor unit, a ductless system can be installed in just a few hours.

Once your installation is complete, there will be up to two inspections by the municipality that issued the permit to verify the mini-split is up to code. The inspections will take place within 30 days of installation for mechanical, and within 10 days if electrical.

Verdict: A window unit is undoubtedly the quickest solution, but the nonintrusive installation process of a ductless system puts both units on the easier side of air conditioning installations.

Monthly Costs and Energy Efficiency 

Although the initial cost of installing a ductless system deters some, any upfront costs will be returned through your monthly electric bill. Ductless systems are renowned for their high-caliber energy efficiency and consistent performance with both heating and cooling.

When looking into cooling system energy efficiency, find its EER rating (it’s Energy Efficiency Ratio). This rating is a measure of how efficient a system will operate when the outdoor temperature is at 95 degrees F. The higher the EER, the more efficient the system is. . 

  • Window ACs have EER ratings around 12.2.
  • Ductless ACs have EER ratings around 16+.

You can also check a system’s SEER rating (its Seasonal Energy Efficient Ratio), which measures how efficiently a cooling system will operate over an entire season.

Ductless mini-splits win when it comes to energy efficiency. A standard mini-split consumes 40% less energy than a traditional window air conditioner. A window unit operates until the desired temperature is achieved and cycles on and off automatically, whereas the variable-speed compressor and monitoring abilities of a ductless system adjust output as needed. This results in more stable temperatures and reduces levels of energy consumption in turn. 

Verdict: Not even the most energy efficient window units can compare to a ductless system’s efficiency.


Washington state utilities offer large rebates for the installation of ductless heat pumps, as the state recognizes them as highly efficient, green-energy heating and cooling systems. These systems help the energy-efficiency-leading state meet its goal to reduce energy consumption and conserve energy in every household. 

Most window AC units do not qualify for rebates as they do not provide an energy efficient option. It’s best to check with your local utility company to verify energy requirements. 

At Alpine Ductless, instead of having to apply your rebate and wait for your check after the project’s complete, we do all the legwork for you. We find the most suitable rebate available in your area and we apply the deduction to your order. You can have your system installed and pay a reduced amount based on your rebate deduction.*

*Please note that not all utilities have the same requirements. In the event that we are unable to file the rebate for you, we will provide all the necessary paperwork to make the process as easy as possible.

Verdict: Most ductless systems will qualify for a rebate. Some window units may be eligible, but always check with an expert before purchasing.


Window AC units tend to be noisy. Because they include the condenser, compressor, and fan in one small box, the sound is quite noticeable. 

Ductless systems, on the other hand, are known for their quiet operation. Mini-splits use very small tubes that connect the indoor unit to the outdoor unit, eliminating the traditional whooshing sound that central AC systems bring, as well as loud motor sounds from window AC units. 

Verdict: Being almost noiseless, a ductless system easily wins this category.


Designed for functionality over aesthetic, it’s undeniable that window units can be a bit of an eyesore. Ductless air conditioning systems are small, slim, and sleek in comparison to a window unit. Because they can easily mount to a wall or ceiling, they’re also far more flexible in where they can go in contrast to a window unit that must be at eye level within a window frame.

Verdict: If the view is important to you, you’ll be disappointed with a window air conditioning system. Both units will be visible, but a ductless system can be strategically installed so it isn’t the first thing that draws the eye when entering a room.


The quality of the unit and the diligence in which scheduled maintenance tasks are performed play a significant role in the lifespan of any air conditioning unit. A window ac unit typically has a lifespan of around 8-10 years. A ductless system has a lifespan of around 20 years when cared for properly.

Verdict: A ductless system has the potential to last for twice as long as a window unit.

Maintenance and Care

For a window air conditioning unit, it is recommended that the filter be cleaned using soap and water. The evaporator and condenser coils should also be cleaned with a vacuum on a monthly basis. An inspection and a professional cleaning of the system should be performed once per year.

Like a window unit, a ductless system also requires monthly cleaning of the filter, as well as a once-every-two-year service to ensure system functionality.

Verdict: There are no significant differences in the upkeep requirements of the two systems.


Unfortunately window air conditioning units are not the safest cooling solution available. The biggest risk associated with window ACs is fire. They are more likely to cause a fire than traditional heating and cooling systems. Also, because you install them in a window, they also take away a potential exit option should a fire occur. 

Another common safety issue with a window AC is the unit falling. Even the slightest error during installation can cause an unsteady unit that may fall and cause damage or an injury – especially to young children. Installation errors can also cause a home security concern, as experienced thieves know exactly how to remove window units to break into the home.

Ductless systems are among the most safe and reliable cooling systems out there. Ductless mini-splits only require a small hole in the wall. Because of that, it does not compromise the integrity of the building in any way. 

Verdict: Ductless mini-splits are a safe option if not one of the safest options for cooling a new addition. 

Heating Capabilities 

Although air conditioning is top of mind for a summer installation project, cooler weather is just a few months away. Keep in mind that a window air conditioning unit will cool the air, but not heat it. You will, in turn, need a separate system to heat the new addition in the cooler months of the year. Common systems for heating new additions in tandem with a window air conditioning unit include electric baseboards, propane wall heaters, a wood stove, or in-floor radiant heat. All are options that will require separate, professional installation. 

Ductless systems, on the other hand, provide both heating and cooling, eliminating the need to buy and install two separate systems. 

Verdict: Ductless systems are the clear winner when it comes to an all-in-one heating and cooling solution.

Which is best overall? Window AC Vs. Ductless AC

Overall, the versatility and energy efficiency of a ductless system makes it the better option in the long run. A window air conditioner offers the benefit of being portable and can be a valid temporary solution. However, the lifespan, flexibility, and energy efficiency of a ductless system ultimately renders it the best solution for cooling your new addition.  

Get a Free Estimate

If you’re adding on to your home or business, installing a ductless system is a great way to ensure cost savings and efficiency for years to come. If you live in the northwest Washington area, the experienced professionals at Alpine Ductless can help! Give us a call or contact us to get a free estimate.

Installing Ductless Heating and Cooling Systems in Thurston County including Olympia, Tumwater, Lacey, Yelm and more!

Want to learn more about ductless air conditioning? Check out our Ultimate Guide to Ductless Heating and Cooling.

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