Air Conditioner for Small Basement Window 2025

A basement with a small window is hard to cool, and the correct small window air conditioner can make a damp, stuffy basement a comfortable retreat.

This guide will discuss the most efficient compact window AC units that can fit small basement windows, and professional advice on installation, sizing, ventilation, energy efficiency, and dehumidification.

Be it a small hopper window or a small slider, we will assist you to find a way out to overcome the heat and humidity in your basement.

Window AC Unit	BTU (Cooling Capacity)	Coverage Area	Min. Window Opening	Notable Features
Amazon Basics 5,000 BTU	5,000 BTU	Up to 150 sq. ft.	23” W x 13” H	Mechanical controls, compact 16” width, quiet (~56 dB)
Frigidaire Mini Compact 5,000 BTU	5,000 BTU	Up to 150 sq. ft.	23” W x 13” H (unit is 16” W x 12” H)	Reliable cooling, 1.1 pints/hr dehumidification , quiet operation (~52 dB)
LG LW5023 5,000 BTU	5,000 BTU	Up to 150 sq. ft.	22” W x 12” H (compact height ~11”)	Ultra-quiet design (~50 dB), easy install kit, washable filter
GE 5,000 BTU Mechanical	5,000 BTU	Up to 150 sq. ft.	21.9–36” W x 13.4” H	2 cooling speeds, low-noise 56 dB, EZ-mount kit for double-hung windows
Midea U-Shaped Inverter 8,000 BTU	8,000 BTU	Up to 350 sq. ft.	22–36” W x 14” H	Ultra-quiet 32 dB design , Wi-Fi smart control, 35% energy savings
Soleus Air Saddle 8,000 BTU	8,000 BTU	Up to 300 sq. ft.	24–48” W x 16” H	“Over-the-sill” saddle design, very quiet, keeps window usable, Wi-Fi enabled

Key Considerations for Small Basement Window AC Units

The selection of an air conditioner for a basement with a small window should be based on size and performance. The following are the main considerations to make before purchase:

Sizing (BTUs) and Room Coverage

The BTUs measure the cooling capacity of a window AC. Depending on the square footage, basement rooms normally require 5,000 to 8,000 BTU units to cool effectively. An air conditioner of 5,000 BTU can cool a small bedroom or office of approximately 100-150 sq. ft.

In case your basement area is bigger or open-style, you might require a high BTU unit (6,000 8,000 BTU) or several small units to cool your basement effectively.

Remember basements are below grade and can be cooler than upper stories. This implies that you may be able to use the lower BTU recommendations because there is reduced heat gain through direct sun. Nevertheless, basements tend to be more humid and poorly ventilated, which may make them warmer. You can always be safer on the higher BTU side as long as your window can fit it.

It is better not to undersize, because an overworked small AC will not be able to cool and dehumidify correctly.

Window Dimensions and AC Fit

The most important thing is that the AC should physically fit your basement window. Take the width and height of the clear opening of the window (with the sash open or removed). The smallest standard window air conditioners (approximately 5,000 BTU) are approximately 15 17 inches wide by 11 13 inches high.

The mounting hardware and accordion side panels however usually need a larger window opening to install. As an example, a lot of compact units require a minimum window width of 22-23 and at least ~14 vertical clearance. (The majority of small window ACs can be installed in window openings between 22 to 34 inches wide and at least 14 inches tall.)

Basement windows are frequently short (hopper or awning type which tilt in) or sliders. In case the height of your window is less than ~12 inches or width is less than ~16 inches, a standard window AC will not pass through the opening. In this situation, you may be required to adjust the window.

A popular fix is to simply take out the window sash completely and fit a wood or plexiglass panel with an opening to fit the AC unit. This will allow you to use the entire dimensions of the window frame. Make sure that the panel is cut to fit tightly and keep the AC firmly in position.

In the case of hopper windows which tilt inwards, you might have to remove the window off the hinges to accommodate the AC, and then fill the left over space above the unit with a custom panel.

Hint: Before buying an AC, make sure to look at the specification of each AC to see the requirement of window opening. To give an example, the Amazon Basics 5,000 BTU model has a minimum window opening size of 23 x 13 inches. The real chassis of the AC is smaller (approximately 16 W x 12 H), so it might possibly fit in a slightly smaller opening.

But the custom mounting without the side curtains is possible, and the standard mounting requires the larger opening to allow the side panels and mounting rails. When installing the AC, ensure that there is always at least an inch or two of wiggle room on top of the dimensions of the AC.

Window Type and Orientation

Think of the style of your basement window. Standard window AC can be installed easiest in double-hung windows (which slide up and down). Sliding windows (slide sideways) and hopper/awning windows (tilt open) are more complicated.

In the case of sliding windows, you cannot install a regular AC on its side (this will ruin the unit). Rather, you can have a special designed casement window AC (a vertical air conditioner) fitted in case your window is narrow but tall enough (usually requires 18-20 height).

But, majority of basement sliders are short and therefore casement AC units will not fit in most cases. In such situations, the whole window pane is normally removed and a standard AC fitted with a custom frame (as explained above).

Newer versions of the window ACs are also available in the form of the so-called saddle or over-the-sill style (such as the Soleus Air model in our recommendations) that rests low on the windowsill. These enable the window to be closed down on the unit.

Saddle ACs also need the window to be opened approximately 15-16 inches high in order to be installed, but when installed they only cover the lower half of the opening. This is a good alternative when you have some extra vertical space and would like to have light or use the window.

Venting and Clearance Issues

When a basement is to be fitted with a window AC, there are some venting issues that may arise. The AC removes hot air and water condensate through the back of the unit, and therefore, the outside part should be well-ventilated and have enough space.

Most basement windows are in window wells or close to the ground and this can trap the hot exhaust:

• Clearance: Make sure that there is at least a couple of inches of space on the back end of the AC. In case it is too near a dirt wall or is buried in a deep window well, excavate or better the well space where possible. The unit requires airflow to be able to dissipate heat.
• Hot Air Circulation: In case the window well is extremely small, a small fan in the well can be used to assist in pushing hot air out or a well cover can be propped open. Hot air that surrounds the unit can stagnate and circulate back to the unit and lower the cooling capacity.
• Rain and Debris: Since the AC can be placed close to the ground, cover it against flooding or excessive rain water. Remove leaves or debris in the window well. The majority of ACs are rainproof, but you do not want the bottom to be flooded. In case your well is prone to accumulation of water, you might have to enhance drainage or not use the AC when it is raining.
• Drip Drainage: Window ACs drip water during the process of dehumidification. Make sure that the condensate has free drainage to the exterior. When the AC is too near the ground, raise it a little on brackets or blocks so that the drain pan does not lie directly on the ground and this may obstruct the drip outlet.

It is also advisable to go out after operating the AC some time to ensure that hot exhaust air is not building up in a confined area. The back end of the unit will be cooled properly by ventilating it and avoiding overheating.

Electrical Requirements

The majority of small window ACs operate on a typical 115V household circuit and consume about 4 to 7 amps. This is normally acceptable in a normal basement room outlet. Simply make sure that the outlet you are using is good and capable of carrying the load (it must be a three-pronged grounded outlet).

Do not use extension cords, but in case you have to, use a heavy-duty extension cord rated to air conditioners. Also, ensure that there are no other big appliances on the circuit you are on, you do not want to trip a breaker.

Safety Many window AC units include a built-in surge protector or resettable fuse on the plug. In case you have an unfinished basement or a damp basement, ensure that the outlet is GFCI protected to be safe.

Installation Tips for Basement Window Air Conditioners

It might take some creativity to install a window AC in a basement, but it can be done as a DIY. The following are some of the tips and steps to assist in installation:

1. Measure and prepare the window: First of all, measure the clear opening of your window to ensure that your selected AC will fit. Take away insect screens. In the case of hopper windows which open inward, it is usually effective to take the window sash/pane out completely to leave a hole that is fully open.
2. Be prepared to support: Small AC units are 35-60 lbs, so make sure you have a way to support it when you are installing it. You may be able to hold the AC outside a basement window on the ground (or a sturdy box) level with the window (ground level). Long-term support should be ideally done by an L-bracket or an AC support bracket mounted to the exterior wall below the unit. This supports and takes off the strain on the window frame.
3. Install the AC: Slide the AC unit into the window opening (inside) pushing until the bottom flange is on the sill with assistance as needed. In the case of a basement window which is low to the ground, you might have to be outside to direct it. Place the unit in the middle and slightly downward facing outside (a tilt of approximately 1/2 inch is suggested so that the condensate water will flow out).
4. Fix it in position: The majority of the window ACs are supplied with mounting brackets or flanges which are fitted to the window frame. When you have a basement window that does not have a moving sash (after removal), you will be attaching the unit to the wood frame or the filler panel. Pilot holes with drills and screws that are provided should be used to attach the side or top brackets. With a custom wood panel over the AC, screw the top flange of the AC into that panel.
5. Plug the holes: Holes around the AC allow warm air, insects and water to enter. If the accordion side panels fit, expand them to cover the side holes and screw them into the window frame. In the case of irregular openings, use pieces of foam insulation or plywood cut to seal above or on sides of the AC. Weatherstrip everywhere. Foam seal strips (usually included) may be pushed between the unit and the frame to make a tight seal.
6. Stability and tilt: Go outside and make sure that the AC is not wobbling but is firmly in place. Adjust or add support brackets on the bottom as needed. Make sure it still has a little downward slope to drain water. Make sure also that nothing on the outside (such as the wall of the window well) is obstructing the air vents.
7. Test and power it up: Plug the AC and turn it on. Check the unit with your hands to feel any air leaks; in case you detect some, apply more weatherstripping or sealant in that area. Check the cooling and ensure that water is dripping outside after it has been running some time (this indicates that the dehumidification is functioning and draining as it should). Check to see that it does not vibrate in any unusual way; and, if it does, you must put some padding on it or screw it down.

These steps will help you to install a window AC in a basement window safely. You should also always refer to the manufacturer instructions on how to install as well because certain bracket designs and steps may differ.

In case your basement window installation is not the usual (no frame to attach to), you may have to be creative with lumber framing or consult a professional. When installed, the unit must be firmly fixed, slightly angled outwards and properly sealed off the indoors.

Energy Efficiency and Noise Concerns

The amount of electricity consumed by any window AC and the level of noise it produces when in operation are two key performance areas of any window AC. A basement will require a powerful unit that does not increase your electricity bill and a silent machine in case you are using it as a living room or bedroom.

Energy Efficiency

EER (Energy Efficiency Ratio) or the latest CEER (Combined Energy Efficiency Ratio) is the efficiency rating of air conditioners, with room ACs. The greater the number the more cooling you obtain per watt of electricity. EER ratings of small window AC units are normally between 11 and 12. Simple 5,000 BTU units that have rotary dials are not Energy Star qualified since they are not very efficient but are average.

In case energy savings are of concern, seek:

• Energy Star certified: These have better efficiency standards. As an example, an Energy Star 5,000 BTU unit can have a CEER of 12.0 or higher. The Midea U-shaped inverter AC (8,000 BTU) has a CEER of about 15 and was the first to receive an Energy Star Most Efficient award, consuming 35 percent less energy than conventional models.
• Inverter technology: Conventional ACs either have the compressor on full power or off; inverter ACs can adjust the speed, which has a huge effect on efficiency and allows constant temperatures to be maintained. Inverter window units (such as the Midea U) are more expensive to purchase but save energy in the long run.
• Adjustable thermostat and eco mode: All the suggested ones have thermostats to turn off the compressor when the desired temperature is achieved. Most also have an Eco, or energy-saver mode that switches the fan on and off in a cycle to check the air, consuming less power. This can be applied in a basement that may not require continuous cooling during the night.
• Right sizing: Another aspect of efficiency is the right sized AC. An over-sized unit will short-cycle (turn on and off frequently) and can be energy wasting, and an undersized one will run continuously at full blast. Try to get a unit which is capable of operating at a moderate, constant speed to keep temperature.

In the case of a small basement window AC, the variation in annual energy cost between models may be only 10-20 dollars but that accumulates over a few summers. In case the basement is going to have a heavy AC usage, then it would be worthwhile to invest in a high efficiency (or inverter) model.

And do not forget to clean the filter on a regular basis, a clogged filter slows down the airflow and makes the AC work more and consume more energy.

Noise Levels

Whether it is a basement or not, a loud AC is annoying all the time. In case the basement is a living room or bedroom, then consider the noise ratings of the unit. The noise of window AC is in dB. Smaller units are likely to generate about 50-60 dB on the low fan settings (this is roughly equivalent to a normal conversation or background white noise).

Noise may be slightly increased on high fan or when the compressor comes on.

The most silent of our suggestions by far is the Midea U-shaped inverter, which operates down to 32 dB, which is very quiet, due to the compressor being largely outside the window, and the inverter making the operation smooth. The common 5,000 BTU units, such as Frigidaire, LG, GE, etc., will be about 50-55 dB on low cool.

As an example, the Frigidaire 5,000 BTU model is approximately 52 dB on low and the LG model is approximately 50 dB on low fan. Practically, they sound like a soft hum or fan sound, which most people find pleasant or even relaxing (it can also be used as a white noise to sleep).

But, in the case of recording music or podcasts in the basement or being very noise sensitive, you may tend to the inverter or saddle type units that are designed to be quieter in operation.

In order to minimize noise:

• The unit should be installed firmly to avoid vibrations. Rattling is normally caused by loose fit. Apply foam padding at the point where the AC touches the frame.
• Maintain the filter and coils in a clean state. The fan can whistle or hiss and work harder due to a clogged filter. Clean filter = easier air flow = quieter.
• Wherever possible, use low fan speeds. Any unit has the highest fan setting which is loud. The low or medium fan will usually be sufficient to circulate cool air in a small basement room without making any noise.

Any window AC will produce some noise, the noise of the compressor (a deeper buzz) and dripping water sometimes. However, on the whole, new units are much quieter and nicer than their older counterparts.

It is also possible to read the user reviews to find out whether a certain model has noise complaints or whether it is considered to be quiet. We point out in our product choices below which ones are said to be low-noise.

Dehumidification and Air Quality Features

Basements are usually problematic in terms of humidity and air quality. A window AC in a basement has one of the best advantages that it will actually dehumidify the air as it cools and will help dry out that clammy basement air.

The following is what you should know about dehumidification and other air quality features:

Moisture Removal (Dehumidification)

As an AC cools the air, it condenses out water too. A small 5,000 BTU unit could remove about 1 pint of water per hour out of humid air. In a muggy day, that will be 20+ pints of moisture taken out, which is the same as the contribution of a small dehumidifier.

This can go a long way in ensuring that a basement is dry and does not have molds and mildew. When your basement is relatively humid during summer, a window AC may help to keep the humidity at bay, to a large extent, when it is in operation.

But in case the basement is very wet (e.g. when water is trickling in or humidity is always high even when it is cold), a special dehumidifier may be required besides or instead of turning on the AC. A few things to note:

• Most window air conditioners lack a humidity % control as do standalone dehumidifiers. However, there are also those that have a Dry mode that basically operates the compressor and fan in a manner that will maximize dehumidification rather than cooling. This may come in handy during days that are not hot but humid.
• Ensure that the condensate of the AC is draining well to the outside (see installation). You do not want that water to back up. Periodically inspect the drip-if it ceases to drip on a humid day, then the drain may be blocked with debris.
• When you realize that the basement is still humid in areas that are not close to the AC, you can employ the services of a small circulating fan to assist in the movement of air. ACs just dehumidify the air passing through them. Proper circulation will make sure that more air in the room reaches the AC to be dried and cooled.
• On really cool, wet days you may not turn on the AC (it is cold), but the basement may get wet. A dehumidifier would be required in such situations because AC would not be running. In summer, however, when the AC is running, it is providing you with dehumidification as a bonus.

Air Quality and Filtration

Window air conditioners are fitted with a simple filter which captures dust and large particles in the air. This filter is normally a washable mesh or foam. This filter should be cleaned regularly (say, every 2-4 weeks) in a basement since a basement can be very dusty or even contain mold spores which you do not want to breathe in.

A clean filter does not only ensure that the air is cleaner but also ensures that there is airflow to ensure that the unit is efficient.

Some more expensive models or brands can include extra filtration or air quality features, including:

• Ionizer or antimicrobial filter coatings: Some models may have an ionizer option to assist in the reduction of odors and pollutants, or a coating on the filter to prevent bacterial/mold growth. These are good, but without them, dehumidification and a clean filter will significantly increase the quality of basement air.
• Vent control: Some window ACs have a small vent lever that may be opened to allow a little outside air. You may have this in a basement to allow a little fresh air circulation, but remember it will also allow humidity in. As a rule, it is better to keep it closed to recirculate indoor air that is more effective to cool and dehumidify.
• Fan-only mode: You can use the AC on fan-only mode to circulate air without cooling. This may be convenient to simply air out the basement or turn on the filter feature on less severe days. It will not dehumidify on fan (because compressor is off), but it will circulate air, which can help with stuffiness.

Finally, in case there are certain air quality issues in your basement (such as its musty smell), take care of the cause too: clean any mould, install a dehumidifier, etc. The window AC will go a long way in ensuring that the air is drier and filtered but it is not a panacea to severe moisture issues.

Consider it as one of the elements of maintaining a healthy basement environment.

Recommended Products: Best Window AC Units for Small Basement Windows

The following are 6 window air conditioners that are suitable to small basement windows. We selected them because of their size, performance and features. Convenience: every product has its Amazon page (with an affiliate link). In every AC, we enlist some of the main features with advantages and disadvantages to keep in mind:

#1 Amazon Basics 5,000 BTU Window Air Conditioner

This Amazon Basics model is a cheap, bare-bones window AC that is ideal to fit in small basement windows. It has the basic cooling and dehumidifying capabilities and lacks smart features, which makes it easy to use and dependable.

It has a small chassis (approximately 16 inches wide) that is one of the smallest in the market, and this is excellent in fitting into small openings.

Features: 5,000 BTU cooling capacity of approximately 150 sq. ft., two cooling speeds, two fan speeds (manual rotary controls), washable filter, and includes a window installation kit (expandable side panels, top rail, etc.). It is also marketed as a 3-in-1 (cooling, fan, dehumidify) feature.

Pros:

• Small size: It fits small windows (minimum 23″ x 13″ opening) ; the unit itself is only ~12″ tall, perfect in a basement opening.
• Affordable: It is usually among the most affordable window ACs on the market, which is why it is an excellent option to use in the basement occasionally or when you have a limited budget.
• Silent: Sound levels of up to ~56 dB on low , a low hum. It is quiet enough to sleep to many users.
• Lightweight: It weighs about 36 lbs, making it easier to work with when installing than other heavier ones.

Cons:

• Simple controls: No digital thermostat, no remote control. You will have to change settings using the dials on the device. It does have a dial thermostat, but it is not as accurate as digital.
• Small space cooling: 5,000 BTU should be used in a single small room or a part of a basement. It might not be able to cope when you want to cool a big open basement or a number of rooms.
• Build quality: It is a budget model, and it is rather simple in its construction. It is effective, yet its durability may not be as high as that of high-end brands (however, numerous reviews state that it does its job just fine).

Conclusion: Amazon Basics 5,000 BTU AC is a decent choice in small basement windows, and it is especially good when you want something cheap and simple. It is effective in cooling and dehumidifying a small space and can be placed in places where larger units cannot.

It does not have bells and whistles, but to most users, that is just fine as a basement unit.

#2 Frigidaire 5,000 BTU Window-Mounted Mini Compact AC

Frigidaire is a household brand in the refrigeration and AC business and this 5,000 BTU mini compact unit is one of the best selling units in small rooms. It is comparable in size and capacity to the Amazon Basics one, but it is a product of a well-known brand that is likely to receive high ratings in terms of reliability.

It is a good choice when you need something that has been tested and you do not mind paying a little extra on the brand name.

Main Features: 5,000 BTU cooling (~150-250 sq. ft. according to Frigidaire, but 150 sq. ft is more realistic ), two cooling speeds, two fan speeds, mechanical rotary controls (on some models) or a version with a remote (digital controls) in case you are interested. It also includes Frigidaire Effortless Temperature Control that switches the compressor on and off to keep the desired temperature.

The dehumidification rating is approximately 1.1 pints per hour moisture removal.

Pros:

• Reliability of brand: Frigidaire units have a reputation of blowing out very cold air and have a long life span. Most users say that this small AC cools more than it should be considering its size.
• Quiet operation: It is sold with the feature of quiet operation and the majority of reviews confirm that it is relatively quiet (51-55 dB range). It is not obtrusive on low fan and the compressor sounds smooth.
• Simple installation: It has small size (16″ W x 12″ H x 15″ D) and can be installed in small windows. Clear installation kit and instructions. It is a fixed chassis (slides in as a unit) that is easy to work with.
• Auto restart: It auto-restarts with last settings in case of power outage, which is a good feature in case of power outages in your area or in case you use a timer plug.

Cons:

• No remote in standard model: The basic model is the mechanical control without remote. There is a slightly more expensive model with electronic controls and a remote, but that may not matter to you, Frigidaire does offer it.
• The side panels are a bit flimsy: The side accordion panels included are a little flimsy (as is usual with ACs). You might find yourself using custom side fillers in a basement window just to have better insulation.
• Thermostat knob is not precise: It is not digital, so you dial in a number on a knob to get the temperature (you have to experiment to get to your comfort level, which is usually 1-7 on the dial). When it is set it stays well, but the first calibration is by feel.

Conclusion: Frigidaire mini 5,000 BTU AC is a proven solution to small rooms. It is perfect in a basement bedroom, workshop or den. You have a quiet, small-sized, dependable cooling and drying unit.

Frigidaire is a safe choice, especially when you want a well-established brand and possibly intend to use the AC extensively during the summer.

#3 LG LW5023 5,000 BTU Easy-Install Window AC

Another great window AC is LG 5,000 BTU (model LW5023, a 2023 model) that is specifically designed to fit small rooms. LG is a company that deals in consumer appliances with a touch of innovation; this AC is known to be very quiet and easy to install.

It is a nice choice in case noise is a major issue, and in case you need a unit that looks sleek.

Important Features: 5,000 BTU cooling capacity up to approximately 150 sq. ft., mechanical controls (2 cool speeds, 2 fan speeds, adjustable thermostat), top-down air discharge with two-way air direction vents. It has an EZ mount installation kit and a slide-out washable filter.

It is interesting to note that LG markets it as Ultra-Quiet, user reports and specs place the sound at about 50 dB on low.

Pros:

• Low noise: Most of the reviewers point out that this LG model is quieter than other brands of the same BTU rating. It is more of background noise than an intrusive hum, which is excellent in a basement TV room or office.
• Slim profile: It is a bit shorter than some competitors due to its dimensions (~17.3″ W x 11.1″ H x 14.4″ D) and this may assist in a tight window. It also has a modern less bulky look due to the smaller front grille.
• Simple installation design: The kit and guide that come with it are simple. It comes with a fixed chassis which you simply plop in the window and fix. The EZ Mount of LG means to slide the side panels in and fasten two brackets, which is quite easy to use.
• Durability and safety: It is equipped with an in-built circuit breaker plug (LG refers to it as a Leakage current detector). LG units are of good durability and come with a one year warranty.

Cons:

• No digital or remote display: This is a simple model with manual dial controls like the rest of the others. To get a remote, you would have to go to LG 6,000 BTU or Wi-Fi (which is physically larger).
• Poor direction control: The air deflector vanes can move up/down and left/right, although some users mention that the airflow is directed slightly upwards by design (this is beneficial to cool a room uniformly, but in a basement with low ceilings you may not feel the airflow as well). Not normally a major problem, a fan can be used to circulate air where necessary.
• Availability: The given model (LW5023) could be a seasonal product in the first place. Make sure it is in stock otherwise an older model LW5016 or LW5017 (basically the same performance) can be used.

Conclusion: LG 5,000 BTU AC is a high-end product in the category of simple window air conditioners because of its silence and quality. It is ideal in basement scenarios where you will be spending much time and you do not want much noise (e.g. home theater or a guest bedroom in the basement).

It is a little more expensive than off-brand units, but it is worth it in terms of comfort and peace of mind.

#4 GE 5,000 BTU Window Air Conditioner (Mechanical Controls)

GE has a good 5,000 BTU window AC which is highly demanded in small rooms and basements. There are two versions of GE, one is mechanical and the other one is electronic controls + remote. Here we are talking about the mechanical one because it is sometimes a bit cheaper and easier (model AHEC05AC).

This unit has a reputation of being well built and cooling well. It is also commonly easily accessible in home improvement stores, which means that it is a common product of choice.

Key Features: 5,000 BTU (it is actually 5,100 BTU according to GE) small room up to 150 sq. ft. 2 cooling modes, 2 fan speeds, mechanical rotary dials (10 temperature settings on the thermostat dial). It has a simple mount kit and adjustable side panels. GE emphasizes a low-noise operation and adds that it is perfect to use at night.

The unit is suitable to fit windows measuring 21.875 to 36 inches wide and 13.375 inches or more.

Pros:

• Strong cooling: It is often noted by users that this GE is over-performing in cooling. It is able to cool small spaces in a short time and keep it comfortable even when the outside environment is extremely hot provided that the space is within its size limits.
• Low noise design: GE has tried to muffle the sound though it is not silent. It is very quiet to many so that they can sleep. The sound is smooth and does not contain irritating rattles. (Approx noise level is mid 50 dB at low, like others.)
• Flexible installation: The window width range down to ~21.9 is a little more flexible than others (some require 23 min). In case your basement window is narrow, it may work in a place where others do not (provided that height is adequate). It is also small footprint (16.4 W x 12.6 H cabinet) which helps.
• Control choices: GE has the same-looking model with electronic controls that can be substituted in case you ever want a remote. It is good that the brand provides both of them; the units are otherwise almost identical in terms of performance.

Cons:

• Old style design: The design and the dial controls are slightly old fashioned. It works, but lacks the modern look of more recent AC designs. This probably does not make much difference in a basement, but should be mentioned in case style is an issue.
• Manual resets: In the case of the mechanical version, in case you place it on an outlet timer or smart plug, you should know that it will automatically turn back on only when the mechanical knob is left in the On position (which it would be). Just to keep in mind, the digital one would keep settings differently.
• Filter: The filter is behind the front grille; to access it you must pop off the whole front plastic bezel. It is not hard (takes a few seconds), although some units have slide-out filters which are a bit more convenient. To get optimum performance, clean the filter once a month.

Conclusion: GE 5,000 BTU is a reliable workhorse that cools small areas. It is quite appropriate to use in the basement: it is small, efficient and not very loud. GE is a great choice, in case you appreciate the support of a big company (warranty, customer service) and maybe you would like to have the possibility of a remote (by selecting the electronic version).

It does not feature any fancy stuff beyond that, but it will do the job and will last several seasons without fuss.

#5 Midea U-Shaped Smart Inverter 8,000 BTU Window AC

Midea U-Shaped Inverter AC is a new design that has attracted a lot of attention and rightly so. It is a larger BTU unit (8,000 BTU) which may be more capacity than some small basements strictly require, but its size and features make it an attractive choice, particularly, in case your basement window is large enough to accommodate it.

The special U-shape enables the window to move down between the indoor and outdoor sections of the AC, and it isolates the noise dramatically and you can still get light and air through the window even when the AC is not in use.

Key Features: 8,000 BTU cooling, suitable to rooms of up to ~350 sq. ft. Inverter compressor technology (35%+ energy savings over non-inverters). Ultra-quiet operation (down to 32 dB) – approximately 9 times quieter than the conventional units.

Wi-Fi enabled, smartphone app and voice control (Alexa/Google Assistant). It is fitted with a special window support bracket that makes it securely mounted. It needs a 22-36 wide and at least ~13.5 high window to be installed.

The window may be closed once installed to almost reach the top of the unit and seal the opening.

Pros:

• Very silent: It is among the silent window ACs in the market. The inverter and the fact that the compressor is placed outside (the window glass separates you and the compressor) make you hear a gentle fan most of the time. Ideal in noise-sensitive areas – in case your basement is an office, bedroom or media room, this AC will not bother you.
• Energy efficient: It has a high CEER (~15) and inverter modulation, which will save you a lot on electricity. There is no overkill to use an 8k BTU in a smaller area since the inverter will only run it at its lower capacity when needed. Actually, it could be more efficient than a smaller unit which is continuously cycling on/off.
• Smart capabilities: There is an integrated Wi-Fi that allows you to operate it through the Midea app or connect it to Alexa/Google. You can program it, switch it on/off when you are not there (e.g. switch on before you get home to cool the basement), or use voice commands. It also possesses a remote control that has an LCD screen attached to it to be used traditionally.
• Window usability: You can still use the window unlike any other AC. As an example, you may open the window on a cool night and get fresh air without taking the AC out, the upper part of the window opens and the AC remains in the lower part. It also prevents less light as AC does not cover the whole opening of the window but just the sides.

Cons:

• Greater price: This sophisticated unit is more expensive than the simple 5,000 BTU ACs, about twice or thrice the price. You are paying the inverter tech and design. But add energy savings and features and it may be worth it.
• Installation difficulty: It is a little more complicated to install. The unit is in two parts (the U-shape), and you have to fix the support bracket that is provided to your windowsill securely. In a basement window installation, when your window sill is extremely narrow or the window is flush to the floor, you might have to be creative in order to use the bracket or support the unit correctly. It can be done (some have put these in odd shaped windows by constructing wood frames).
• Height requirement: You should have about 14″ of open window space to accommodate it. Some basement windows may be a bit less than that. Measure carefully. It is also quite heavy (~55 lbs) and you may require an assistant to install safely.

Verdict: The Midea U-Shaped AC is a game-changer provided you have the budget and your basement window is just big enough. It offers strong cooling and dehumidifying of larger spaces, runs in a whisper, and will not make your basement window a permanent dark hole.

It is a perfect choice of a basement apartment or a living space that is used regularly and comfort and convenience are the priority. The first attempt to install it is rewarded by everyday pleasure of using it.

#6 Soleus Air “Over-the-Sill” Saddle 8,000 BTU Window AC

Another new design is the Soleus Air saddle-style air conditioner which is effective in some basement windows. This unit does not sit in the window opening like a conventional AC; rather it saddle-straddles the window sill. Most of the unit is suspended indoors against the wall, part of it protrudes out like a saddle.

Then the window is closed down on the top of the AC unit. The advantage is that you do not require such a high opening to install and you do not lose much of your window view and light.

Important Features: 8,000 BTU cooling capacity (on rooms of about 300 sq. ft.), inverter-like operation to save energy (it is Energy Star rated). Extremely low sound (advertised at ~38-40 dB). The newest model has Wi-Fi with smart control (Alexa compatible).

It is suitable to windows 24 to 48 inches wide and must have a maximum window sill thickness of 11 inches (it must have a sill to rest on). Notably, you should have a vertical clearance of approximately 16 inches to insert the unit in the window first, and then you can close the window about 3/4.

Pros:

• Window protection: You do not lose your entire window. The unit is at the bottom and therefore light still penetrates above it. It is also possible to open the window above the unit when the AC is not on. Perfect in basements where natural light is a commodity.
• No external brackets are required: The design is very sturdy on its own (it basically clamps the window sill). There is no need to screw anything on the outside wall. This is good when you are not able to drill into the outside of the building or when your window frame is metal/concrete.
• Silent and effective: Just like the Midea U, the compressor is external and there is a gap that muffles the noise. It is described as whisper quiet. It is also very efficient (it is an inverter). Thus you have a comfortable low-noise environment.
• Digital controls and Wi-Fi: It is remote-controlled and has a digital display on the machine. It has Wi-Fi control and voice control. You are able to select modes such as Cool, Dry, Fan-only and set temperature to the desired level.

Cons:

• Partial window blockage: It does not block the usage of the window but approximately 9-10 inches of the lower part of your window will be covered by the height of the unit. This may obstruct a large portion of it in case your basement window is very short in the first place.
• They are usually superior in standard height windows. In short basement windows you may not be able to get it in at all, unless you have the 16 inches necessary to get it in.
• Greater price: This is an expensive product as well. It is an investment though a convenient one. Moreover, Soleus Air is a somewhat less popular brand, yet they were the first to come up with such a design.
• Drip indoors (on older models): Earlier models of saddle ACs had an interior drip tray that would occasionally require emptying. This and newer models have better auto-evaporation and most of the condensate is vented out. Only make sure you level it out with instructions so that it drains. You may have a small reservoir indicator in case it has to be drained.

Conclusion: Soleus Air saddle AC is an outstanding product in case you have a compatible window and you do not want to compromise the functionality of the window. This might be helpful in a basement where you might want to use it in egress windows (you can not fill them in completely due to code reasons) or any application where you want a less obtrusive installation.

It dehumidifies and cools as well as an average 8k BTU unit but with extra silence and intelligence. Make sure that you have enough height of the window and installation should be easy. When you are in it, you will hardly realize that it is an AC, so quiet and seamless it is.

FAQs About Basement Window ACs

Q1. Can I install a window AC in a small basement window that’s only 10 inches tall?

A: The opening of a window is 10 inches tall which is a pity, as it is too small to fit any standard window AC unit. The mini window ACs require about 12.5 to 13 inches of vertical space to fit into.

In case your hopper window is very short, you can do the following: 1) Take out the whole window frame to get a couple of inches and install a panel with an AC instead of it (this can be a handyman job and not easily reversible). 2) Install a through-the-wall AC by making a hole in the wall (extreme and needs to be planned well so as not to compromise the structure). 3) The easiest: think of a portable AC unit which is placed inside and exhausts outside via a small tube.

Portable ACs are equipped with window kits that are able to fit in small openings (some require a 5″ circular vent). The question is about window units, but in very small windows a portable AC or a mini-split system may be the only possible cooling solutions.

Always keep in mind that you should never operate a window AC on its side, it should fit properly, and in case it does not, then do not force it, instead find another solution.

Q2. My basement only has a slider window that opens 15 inches wide. Are there window ACs that can work with that?

A: A 15 wide slider window is a difficult situation since even the smallest window AC is 15-16 wide. One of them is a casement style window AC – these are vertical and narrow units which fit vertical window openings. But they need the window to be tall enough (say 20 or more inches high), which is no good when the constraining dimension of your window is its width.

A casement AC might fit in a window that is 15 15 (and say 24 high) (opens vertically). However, with 15 max width of the opening, none of the standard AC will fit in.

In practice, this has been overcome by just taking out the slider window and using the full frame (which may be, say, 30 wide in total with the center post taken out). Then a small AC can be inserted in one of the sides of the opening and the remaining covered.

This is somewhat complicated. Alternative solution: two smaller windows (one AC per window) are available. Otherwise, as in the case of very short windows, a portable AC venting through that 15″ hole may be the way of least resistance.

Q3. Will a window AC remove enough humidity in my basement, or do I still need a dehumidifier?

A: A window AC will dehumidify the air considerably whenever it is on (in fact, it can remove quite a lot of moisture, e.g., ~1 pint per hour at 5,000 BTU). In most basements during summer, this is all that is required to maintain the area comfortable and avoid that clammy sensation.

In case your basement becomes humid only during hot days, the AC should be sufficient. But in case your basement has a persistent problem with humidity (it is damp even in the mild weather, or moisture is creeping in), you may still require a special dehumidifier even in cooler seasons when the AC is not on.

The AC can be used with a dehumidifier, some individuals use the AC during the day and a dehumidifier at night. Check your humidity: it should be below 60 percent to avoid mold.

The AC will be very useful; a dehumidifier as an addition will be useful in case you feel that the AC is not sufficient alone.

Q4. Is it safe to leave a basement window AC in place during winter?

A: It is usually advisable to take out and store a window AC during the off-season, particularly a basement window. The reason is as follows: 1) Freezing and debris: During winter, water may freeze in the unit or around it, which may damage some parts. As well, leaves or trash may be piled up in an idle unit. 2) Drafts: Even a well sealed AC will allow some cold air to enter around the edges.

This may cause the room to be colder in a basement and increase the workload of your heating system. 3) Security: A window AC left in place may be a somewhat less secure barrier than a closed/locked window (depending on how it is installed).

In case you do not wish to eliminate it, at least cover it with an insulating cover. Exterior AC covers can be found which cover the outside part to prevent wind and snow. Weatherstrip any openings, too. However, the most appropriate thing to do is to remove it, keep it somewhere dry and seal the window during winter.

It is relatively easy to reinstall it in the spring (and most modern units are lightweight and slide-out chassis to simplify installation).

Q5. How much will a small basement window AC increase my electricity bill?

A: It is not very expensive to operate a 5,000 BTU window AC as compared to larger AC or central AC. It varies with use but a 5,000 BTU unit will use approximately 500-600 watts.

Assuming you run it 8 hours a day, that is about 4 to 5 kWh a day. That would be ~150 kWh in a month (30 days). Assuming that your electricity rate is 0.13/kWh (national average in the US is approximately 0.10-0.20), then 150 kWh will cost you approximately 19.5 (twenty bucks a month). Therefore, a couple of dollars a week of quite regular usage.

An 8,000 BTU inverter unit such as the Midea U may have a slightly higher wattage at peak (maybe 700W), however, since it is more efficient and is frequently used at partial loads, its energy consumption may be comparable or even less in the long run when compared to the same cooling output.

In case you use the AC not all the time (e.g. only when you are in the basement), the price will be correspondingly lower. To reduce cost: maintain the thermostat at a moderate level (e.g. 75F rather than 70F), only use the AC when necessary, make sure the area is insulated (you are not cooling the entire house), and use the energy saver mode of the unit, in case it has one.

On the whole, a small window AC is among the less costly methods of cooling a room.

Q6. Do I need to vent a basement window AC unit differently or worry about carbon monoxide?

A: No, a window AC does not need special venting except to stick the back end out the window as usual. Window ACs are self-contained and do not emit carbon monoxide or any combustion products, they are powered by electricity only.

Carbon monoxide is a problem only with fuel-burning appliances such as gas heaters or generators, which you must never operate indoors without venting. The window AC uses the indoor air, cools/dehumidifies it and returns it into the room, and releases the heat to the outside.

Therefore, as long as the back of the unit is outdoors, you are good to go, no exhaust hose is required as it is the case with a portable AC. Simply make sure that the backside gets some breathing room as mentioned.

The only feature that has to do with venting is that some window ACs have a vent lever that you can use to allow a little outside air to come in to ventilate, but that is your choice.

To sum up, use your window AC in a basement as you would in any other room it does not produce dangerous gases and it will exchange heat correctly provided that it is installed with the back outside.

All these factors and the right choice of the unit will help you cool a basement with a small window. The above-mentioned AC units provide a variety of solutions to various needs, including ultra-quiet ones, as well as basic, budget-friendly coolers.

When installed and maintained properly, your basement can be a cool dry refuge even during the hottest days of summer.