Guide to Air Conditioning a Windowless Room (3 Ways)


Many people rent a small windowless room because it is much more affordable. However, they are struggling to cool their room without windows. So, I went on to find out the solutions.

Affordable rooms are tiny. So, a window air conditioner will do. But, if your room has no windows, a window AC is out of the picture and thus, how do you stay comfortable?

To have an air conditioner in a windowless room, you most likely need to drill some holes through the wall. An air conditioner must transfer heat from indoor to outdoor. Without getting the heat out of your room, it is impossible for the air conditioner to cool the room.

Getting a stand fan or air cooler can provide some cooling but they are not enough to handle the hot weather during summer. Not only they can’t bring down the room temperature, but they also unable to dehumidify the air which is the main factor of you not feeling comfortable (we feel very sticky when the air is humid).

1. Use a Ductless Mini Split Air Conditioner

A ductless mini split air conditioner has an indoor and outdoor unit. Usually, the indoor unit will be installed up high on the wall in your room while the outdoor unit will be installed outside of the house. The two units are connected by copper pipes and cables.

How Much Does It Cost?

For a small room, a ductless mini split air conditioner cost around $700-900 while a decent window air conditioner costs around only $200-400. A ductless mini split air conditioner is about 3 times the price of a window air conditioner.

Ductless mini split air conditioners most likely require a professional installation. According to HomeAdvisor, a typical professional installation for a ductless mini split air conditioner is $500. The installation cost may increase due to factors such as the distance between the indoor and outdoor unit, location and accessibility. However, DIY installation is possible.

How’s the Installation?

To install a ductless mini split air conditioner, you’ll need to drill a hole at a size of about 3-1/2″ through your wall. Then, you’ll need to put a few screws onto the wall of your room for the indoor unit and outside the house for the outdoor unit. Finally, you’ll need to connect the pipes and cables. Also, you need to channel a PVC drain pipe to the nearest floor trap to discharge the condensate water.

Following is a DIY video by MrCool for you to get a sense of how it is like to install it by yourself:

Reasons to Buy

  • Silent Operation – When operating at low fan speed, the mini splits produce noise at about 20dBA only (barely audible) while window air conditioners usually generate noise at about 50dBA.
  • Excellent Comfort – Most mini splits are inverter type where they can regulate the room temperature precisely so that you are more comfortable and sleep better.
  • High Energy Efficiency – The inverter mini splits can reduce their cooling power when a room is sufficiently cooled. Thus, they don’t waste energy.
  • Space Saving – Ductless mini splits are installed up high on the wall. Unlike a portable air conditioner, the mini split gives you more space.

Reasons NOT to Buy

  • No Permission – If the house owner doesn’t allow you to make holes on the wall, you can’t install the ductless mini split air conditioner. However, he/she should also provide solutions to you.
  • Too Difficult to Install – If your room is located at the center of the house, you may need to drill multiple holes all the way from your room to outside the house which is affecting other rooms.
  • Out of Budget – Ductless mini splits are expensive but, if you need the cooling, it is worth investing for your comfort and sleep quality.

Best Ductless Mini Split Air Conditioners for Windowless Room

Typically, a windowless room is tiny. Many rooms without windows only require about 5,000-8,000 BTU of air conditioning cooling capacity. But, the lowest capacity of a ductless mini split air conditioner is 9,000 BTU. So, I recommend using an inverter type mini split air conditioner.

Compared to conventional air conditioners, inverter air conditioners are capable of reducing their cooling power by slowing down the speed of their compressor. A typical inverter split air conditioner can maintain operation anywhere between 4,000-10,000 BTU. Therefore, not overcooling your room and wasting too much energy.

If you decided to go for the mini split, the following are my top picks from Amazon, they are all inverter type and have a heating function:

2. Consider a Vented Portable Air Conditioner

A vented portable air conditioner is a floor-standing air conditioner that requires a hose to discharge hot air to the outside of the house. Do not confuse it with a ventless portable AC or evaporative cooler as both are very different products.

A vented portable air conditioner is a lot more convenient than the ductless mini split. But, you still need to drill a hole in the wall to discharge the hot air. The hole is usually at a low level, about 2 feet above the floor and you can block the hole behind the portable AC so it looks better.

Best Portable Air Conditioners for Windowless Room

A vented portable air conditioner cost around $300-500. It doesn’t require a professional installation. However, you’ll need to drill the vent hole by yourself.

Some portable ACs cost as much as $700-800 but, I don’t see much difference from the affordable ones. Hence, I compared a few of them and below are my top picks from Amazon:

Problems with Portable Air Conditioners

The number one complaint must be the noise level. Portable ACs are loud and noisy. Most of them are around 60dBA. Many manufacturers marketed them as 50dBA but they are not true, at least according to the customer’s reviews on Amazon.

If you listen to the video posted by the customers on Amazon, I don’t think you can sleep with that level of noise. Some people can tolerate that because they may be using it in the living room, not a small bedroom.

Another issue with the vented portable air conditioner is the drain water. Some people complained that the drain water has been overflown while some people have no issue at all.

Air conditioners produce more drain water when there is more moisture in the air. In another word, if you’re living in a high humid place, the AC will produce more drain water, natural evaporation may not be fast enough and hence, you may need to put an extra bucket under it to collect the drain water.

Finally, affordable vented portable ACs mostly don’t have a heating function unless you opt for the expensive one. But, the expensive ones are priced at close to the mini split, might as well go for the mini split.

3. Possibly a Through-the-Wall Air Conditioner

A through-the-wall air conditioner is more or less like a window air conditioner but installed in the wall instead of at the windows. Through-the-wall air conditioners are most likely not practical because you’ll need to cut a big opening on the wall of your rented room.

Thus, this part is just to let you know that such types of air conditioner existed. However, some owners do provide an opening specifically for their tenants to install a through-the-wall AC. They already cut open their wall to a standard size and put on a wall sleeve for their future tenants to just put a wall air conditioner on the sleeve.

Nonetheless, if your rented room doesn’t have a wall sleeve already, making one is mostly not permitted by your landlord. The wall opening needs to be around 16″x26″ through the wall. If I’m the landlord, I probably don’t allow that also. I’ll just ask my tenant to get a split or portable air conditioner.

Other Possible Solutions

Although some of these solutions may look silly and impossible, it still worth knowing them and perhaps give them a try:

a) Share from a Central Air Conditioner

Check with the house owner or other tenants if they are using a central air conditioner and still have spare capacity for you to tap on another air conditioner.

Central ACs such as multi-split and VRF have multiple ports for several indoor units. If you are lucky, you’ll just need to buy an indoor unit and connect copper pipes to the central condenser.

b) Share from a Ducted Air Conditioner

Again, check with the house owner or other tenants if they are using any ducted air conditioners and they have sufficient cooling to share a bit with you.

You can simply extend the ducting and install a supply air diffuser in your room to share some of the cooling. However, you have no control over the air conditioner. Well, at least you can sleep better. Remember to install a return air vent to balance your room pressure.

If you are considering it, do check with your local HVAC expert because extending the ducting requires you to open the ceiling for some messy work. Besides, the house owners may not allow it.

c) Share Cooling using Exhaust Fans

If the room next to yours has sufficient cooling power, you can install one wall mount exhaust fan to take in the cold air and another one to return the air back to the room.

Don’t use just only one fan as your room will be pressurized. Use exhaust fans at about 250-300 CFM of airflow will do for a small room. Choose exhaust fans with auto shutter function to maintain privacy. A suitable one that I found on Amazon is SAILFLO Exhaust Shutter Fan 8 Inch 300 CFM, 2 Direction Reversible Strong Airflow Ventilation Blower for Bathroom Attic Kitchen Window Basement, 8″ Diameter Propeller – 12″×12″Panel.

However, you’ll need to cut the wall too. Be sure to get everyone’s consensus before proceeding.

Conclusion

If I were you, I’ll go for a ductless mini split air conditioner. I’ll save up until I can afford it. If I’m moving out, I can bring along the AC or negotiate with the landlord for a discount if I’m leaving the AC behind for the next tenant. Furthermore, you can always look for an installment plan to reduce the burden.

To me, sleep quality is the most important thing to keep me focused during work and thus, perform better and earn more salary. If I can’t get enough sleep, I don’t perform well and my mind is not thinking clearly to make good decisions.

If you ask me, among my top 3 picks for the ductless mini split AC, I recommend DAIKIN 9,000 BTU 17 SEER Wall-Mounted Ductless Mini-Split Inverter Air Conditioner since I had experience with Daikin brand ACs and they are reliable.

Lastly, I don’t think anyone should suffer from the cooling and heating problem in a windowless room. After all, we get an affordable room just to make some living and feed our family. I wish you all the best. Cheer!

Yu Chang Zhen

Yu was working in the air conditioning industry for the past 7 years, covering from design to installation and maintenance. Yu wish to share all the things he learned with the people around the world.

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