No windows? No problem! Whether you are furnishing a basement, a closed office, a small room, or a new workshop studio, you might be wondering how to cool off a room with no windows. Indeed, windowless spaces come with a few requirements if you want to make them healthy and comfortable. One of these is proper temperature — but equally important are ventilation and humidity control. According to ASHRAE Standard 62.2, windowless rooms need mechanical ventilation to maintain indoor air quality and prevent moisture buildup that can lead to mol .
evaCHILL
The most effective cooling device
One of these requirements is the proper temperature.
So how do you cool a windowless room? We have selected the most popular and efficient best ways to cool a room with no windows.
1. Portable air conditioner
To get some cool air into your space, you can go for a portable air conditioner for a room with no windows.
make sure you choose a portable air conditioner suitable for a windowless environment. Most portable AC models come with an exhaust hose to remove hot air, typically through a window. If your room has no window, you must still vent the hot air outside, otherwise the unit will not cool and can even raise the room temperature . Alternatives for venting without a window include:
-
Through a wall (requires cutting a 5-6 inch hole)
-
Through a dryer vent (check hose size compatibility)
-
Through a sliding door (using a vertical venting kit)
-
Through a drop ceiling (common in basements and offices)
Portable ACs for windowless rooms typically cost more than standard models because they require additional venting solutions or are specifically designed for spaces without windows. Alternatively, evaporative air coolers (swamp coolers) use a completely different cooling method, water evaporation, and do not require any exhaust venting, making them ideal for windowless spaces (though they work best in dry climates, humidity below 50-60%).
For example, if you are looking to cool your personal space in a room without windows, we recommend using an evaporative air cooler as the best way to cool a room with no windows.
Pros:
- You can quickly move around the portable air conditioner in between the different rooms of your place
- Ideal for rentals and temporary housing
Cons:
- You need a specific model for a windowless space which can be more expensive
Read also: If your air conditioner is producing unusual noise
2. Floor fan with ice
Old school, yet efficient. On its own, a fan won't do much for cooling a room without windows because it will only move around the hot air already present in the room. However, you can upgrade it by placing ice in front of it, which will decrease the temperature of the air.
We understand how it can be a hassle! Getting the proper amount of ice, getting rid of the melting water, getting the ice again, etc., can become a never-ending cycle!
The evaporative air-cooling method is close to the "fan plus ice" combo. Except with an evaporative air cooler, you simply need water in the tank — no ice required.
Pros:
- Good temporary solution
- Low price
Cons:
- This cooling method can be a hassle
3. Through-the-wall air conditioner
As you may have guessed, a through-the-wall air conditioner is installed through the wall and not through the window, which makes it great for cooling a windowless room. You seamlessly install it via a sleeve mounted inside the wall.
While through-the-wall ACs are one of the most efficient solutions for windowless rooms, they come with higher upfront costs due to installation fees and the unit type. Total costs typically range from $700 to $2,300 depending on the complexity of the wall and electrical work.
Pros:
-
Efficient whole-room cooling
-
No window needed — permanently installed through the wall
-
Quieter than portable ACs (compressor is outside the room)
Cons:
-
Higher upfront cost ($700–$2,300 installed)
-
Not suitable for rentals without landlord permission
-
Requires professional installation and a hole in the exterior wall
-
Difficult to move or take with you
Read also: Arctic Air Cooler Reviews and Best Alternatives
Safety note: Through-the-wall ACs must be installed according to local building codes. The National Fire Protection Association (NFPA) recommends ensuring proper electrical wiring and clearances around the unit to prevent fire hazards.
4. Ductless air conditioner
The ductless system links individual rooms to the central outdoor compressor. The system itself consists of the outdoor unit and numerous indoor units. So, if you are looking for a ductless air conditioner for a room with no windows, the prerequisite is having a system installed for the whole house. Then, you can mount a ductless ac to cool a room without windows.
As you can imagine, this is not the cheapest way to cool a room.
A single-zone ductless mini-split system for one room typically costs between $1,200 and $4,500, with the average around $2,800. Prices vary based on unit size (BTU), efficiency rating (SEER), and installation complexity. Multi-zone systems for larger homes can cost $5,000–$15,000, but for a single windowless room, you're looking at the lower end of the range.
Also, if the room is relatively small, it is easy to get the sizing wrong, and you may end up installing a model which is way too strong for a little space. We have covered the correct AC sizing in one of our recent articles, so that you can decide on the size while you research how to put the AC in the room without windows.
Pros:
-
Efficient whole-room cooling
-
No window needed, only a small hole for conduit
-
Very quiet indoor unit (20-40 dB)
-
Energy-efficient (up to 30% more efficient than window ACs)
Cons:
-
Higher upfront cost ($1,200–$4,500 for single zone)
-
Requires professional installation
-
Not suitable for rentals without landlord permission
-
Requires an outdoor location for the compressor unit
When choosing a ductless system, look for the Energy Star label — models with this certification are at least 10-15% more energy-efficient than standard units and often qualify for local rebates.
5. Ceiling fan
You can opt for a ceiling fan to avoid installing an AC in a room without a window. Ceiling fans are a simpler, low-tech solution compared to ductless or portable AC units. They don't actively cool the air, they create airflow that makes you feel cooler through the wind-chill effect (evaporative cooling on your skin). In hot, humid climates without proper ventilation, a ceiling fan alone won't lower the room temperature. If you live in a sweltering area, a ceiling fan will help the air circulate within the room. However, it won't decrease the temperature.
Whether ceiling- or floor-mounted, devices like fans might not do the job entirely if the initial temperature is already high. To ventilate the room, make sure you keep the doors open when the fan is working for proper air flow between the house's rooms.
Energy efficiency: Modern ceiling fans use 15-90 watts (depending on speed and blade size), far less than a portable AC (800-1,500W). Energy Star-rated models can save up to 60% on operating costs compared to standard fans. However, they don't lower air temperature, they only create airflow.
Read more about: What’s the Best Fan for Sleeping?
6. Evaporative air cooler
If you only need to cool your personal space (a desk, bed, or workstation), an evaporative air cooler is a better choice than a traditional AC for a windowless room. Evapolar devices are specifically designed for this purpose, they create a "cool bubble" around you, directing airflow within a 3-4 foot radius rather than wasting energy on the whole room. Then, you can simply direct the airflow at you and work out, create, chill or enjoy the gentle breeze when you need to focus.
Swamp coolers like Evapolar do a perfect job in cooling the space around you without wasting the energy on the whole room. Even though evaporative coolers can't cool down the entire room, there are several tricks you can use to increase their efficiency and make the best out of these small, powerful devices.
Pros:
-
One of the cheapest ways to cool a personal space in a windowless room
-
No installation required, just plug into USB
-
Portable: move between rooms easily
-
Energy-efficient: 7.5-12.5W (less than a phone charger)
-
No window or venting needed
-
Adds moisture to dry air (beneficial in dry climates)
Cons:
-
Cools only your personal zone (3-4 ft), not the whole room
-
Works best in dry climates (humidity below 50-60%)
-
Not effective in high-humidity environments
A room without windows requires ventilation, correct humidity levels, air circulation, and a relatively low temperature. Disregarding these requirements can lead to mold appearance and bacteria growth. In addition, stale, warm air is never good for functioning, regardless of how you plan to use the room.
Your final decision on how to cool a windowless room depends on these key factors:
-
Room size: A large room requires a more powerful cooling solution (vented AC, through-wall, or ductless). A small personal space can be handled with an evaporative cooler.
-
How you use the room: For a workshop or gym where you're active for hours, you'll need stronger cooling. For a desk or bedroom, personal cooling may be enough.
-
Humidity levels: ASHRAE recommends maintaining indoor humidity between 30-60% for health and comfort. Evaporative coolers add moisture and work best in dry climates; humid spaces may need a dehumidifier.
-
Energy costs: Evaporative coolers (7-12W) are the most energy-efficient. Vented ACs and ductless systems use far more electricity (800-5,000W).
-
Your temperature preference: If you need whole-room cooling, choose AC. If you prefer personal cooling and don't mind slight humidity, choose an evaporative cooler.
Read also: Top 4 Best Dog House Air Conditioners
Your final decision on how to cool a windowless room depends on these key factors:
-
Room size: A large room requires a more powerful cooling solution (vented AC, through-wall, or ductless). A small personal space can be handled with an evaporative cooler.
-
How you use the room: For a workshop or gym where you're active for hours, you'll need stronger cooling. For a desk or bedroom, personal cooling may be enough.
-
Humidity levels: ASHRAE recommends maintaining indoor humidity between 30-60% for health and comfort. Evaporative coolers add moisture and work best in dry climates; humid spaces may need a dehumidifier.
-
Energy costs: Evaporative coolers (7-12W) are the most energy-efficient. Vented ACs and ductless systems use far more electricity (800-5,000W).
-
Your temperature preference: If you need whole-room cooling, choose AC. If you prefer personal cooling and don't mind slight humidity, choose an evaporative cooler.
FAQ:
1. Can an AC work without a window?
Yes, but it depends on the model. Options include ductless mini-splits, through-the-wall ACs, and evaporative coolers (which don't require venting). Standard portable ACs need an exhaust path, without one, they won't work effectively.
2. What is the best air cooler for a room without a window?
For personal cooling (desk, bed, or workstation), Evapolar air coolers are an excellent choice, they require no window, no exhaust hose, and use only 7-12W. They cool a personal zone within 3-4 feet (1 meter), but they are not designed for whole-room cooling.
3. Can I use an AC for a basement with no windows?
Yes, ductless mini-splits and through-the-wall ACs are good options. However, basements often have higher humidity, according to ASHRAE, indoor humidity should be kept between 30–60% to prevent mold growth. Consider a dehumidifier if needed.
4. What is the cheapest way to cool a windowless room?
Evaporative air coolers (like Evapolar) are the cheapest option for both initial investment and energy use (7-12W). However, they work best in dry climates (humidity below 50-60%) and cool only your personal zone, not the whole room. For whole-room cooling, consider a vented AC or ductless system.
5. Can you have an AC unit without a window?
Yes. You can choose from ductless mini-splits ($1,200-$4,500), through-the-wall ACs ($700-$2,300 installed), or evaporative coolers ($99-$229) for personal cooling. Unlike standard portable ACs, these don't require a window, but each has different costs, installation needs, and cooling capabilities. Refer to the comparison table in this article to choose the best option for your space.
⚠️ Important humidity note for windowless rooms:
In rooms without windows, proper ventilation and humidity control are essential for health and comfort. ASHRAE recommends maintaining indoor relative humidity between 30-60% to minimize mold and bacteria growth . Evaporative coolers add moisture to the air and work best in dry climates (humidity below 50-60%). In already-humid environments, they may not be the best choice. Regardless of your cooling method, monitor humidity with a hygrometer — if levels exceed 60%, consider using a dehumidifier in addition to your cooling device.