Ventilation must both supply fresh air and remove stale and moist air so as to minimize the risk of structural damage (damp) and adverse health effects (mold, gas buildup, etc.). Windows are a great natural source of ventilation, but there are many alternative options if you are dealing with a windowless room, including the 15 we list below.
1. Ventilate the Room Using an Exhaust Fan
When you do not have a window in a room, the most common alternative is to install an exhaust fan and then vent it to the outside of the house. It has to be vented outside in order to comply with section M1501.1 Outdoor discharge of the International Residential Codes (IRC).
An exhaust or extractor fan system is a highly effective method that removes or exhausts stale and moist air from the room, thus satisfying one ventilation requirement. Then the second ventilation requirement, that of supplying fresh air into the room, is satisfied through a passive negative pressure effect created by exhausting the stale air.
As the old air is vented outside, it lowers the air pressure in the room, creating a pressure gradient. Fresh (or at least fresher) air from other rooms of the house and from outside will move down the pressure gradient into the room through any doors, vents, cracks, or holes.
An advantage of this type of ventilation is that it is effective even if you have to keep the interior room door closed for reasons of security, safety, or privacy.
In some rooms, an exhaust fan can be a necessity, not just a good option.
Exhaust Fan Options
The popularity of this ventilation method means that you have a plethora of options. You can have a ceiling insert fan, a wall insert fan, and an inline fan.
Ceiling insert fans are great for windowless bathrooms. Hot and moist air that needs to be removed from the room naturally rises, making a fan located on the ceiling more efficient than one on the wall.
Wall insert fans are a good option if the room has an exterior wall and limited access to an attic or crawl space, which would make running ducting challenging.
Inline fans are not located at the room-side of the ducting. Instead, they are set at some point further along in the ductwork. These are a less costly option when you want to extract air from two rooms using the same ducting.
2. Set up a Positive Pressure Ventilation System
Exhaust fans are part of a negative pressure ventilation system, but there is also a positive pressure ventilation system option that is similarly effective but less common.
In a positive pressure ventilation system, fresh air is mechanically pumped into a room, thereby satisfying one aspect of proper ventilation.
As more air is pushed into the windowless room, the internal air pressure increases. A pressure gradient is created, which causes stale and moist air to leave the room through doors, vents, cracks, and holes, moving to areas of lower pressure. These may be adjoining rooms, outside, or both.
As with the exhaust fan system, positive pressure ventilation is a good choice if you cannot keep the room door open.
Positioning a Positive Pressure System
The best place to install the positive pressure ventilation system inlet is in a place with the fewest exit points (doors, vents, etc.).
The reason is that these spots are the most likely to catch and hold stale air. By locating the inlet here, you force the old air out of this area and towards an egress point in the room.
If you were to set up the system so that the fresh air was pumped into the same side of the room as the vents or interior doors, then the old air would simply be forced towards a solid wall, and you will have a much less effective system.
3. Combination of Positive and Negative Pressure Ventilation System
You can install a combined positive and negative pressure (exhaust fan) ventilation system.
This is a very effective but more expensive option than either of the systems by themselves. Yet, there are certain circumstances where it may be the safest option, not just an effective one.
Suppose you are planning to use the windowless room for a hobby or home-based business that involves potentially toxic substances that will produce fumes (for example, model building and nail art). In that case, actively removing the harmful fumes and replacing the air volume with guaranteed fresh air is a much safer system.
Additionally, the passive side of each system, i.e., old air being forced out by the positive system and new air being pulled in by the extractor system, will still be in effect, compounding the active processes.
4. Set up an Inline Fan and a Loose Duct for a Temporary Solution
There are circumstances under which you may be required to set up a more effective ventilation system temporarily.
For example, a dry storeroom does not require the best ventilation system out there, but if you are painting the storeroom, keeping the door open is not going to ensure you are well-protected from the paint fumes.
In cases such as these, you can set up an inline extractor fan in a length of loose flex-duct.
Put one end of the ducting in the windowless room and run it to either a very well-ventilated room or directly outside. Venting your temporary duct outside is definitely the better option if you can manage it without setting up a maze of tubes all over your house.
Make sure you put the inline fan into the duct facing the right direction!
If you are going to be painting a room, you might also appreciate these tips on how to stay safe while painting.
5. Create Airflow Using a Passive Roof Vent
Passive roof vents are a form of natural ventilation (as opposed to mechanical ventilation). Similar to exhaust fan systems, they involve running ductwork from the windowless room to the outside of the house.
However, as the name suggests, passive roof vents rely on natural movements of air instead of using an exhaust fan to actively pull the stale and moist air out of the room.
All types of natural ventilation are less controlled than mechanical ventilation, and a passive roof vent is no exception. Its effectiveness is reliant on external windspeeds, internal air movement, and outside air pressure in relation to internal air pressure.
Passive Roof Vent Variations
You have options when it comes to the installation of a passive roof vent.
There is a normal, static vent. This is essentially just a hole cut into the roof. Of course, there is a level of protection against rain, debris, etc.
You can opt for a ridge vent, which runs the length of the roof’s peak (or at least a portion thereof).
Installing a mushroom vent is a really good option. It is not beautiful, and it will stick up from your roof, but it is possibly the most effective of the passive roof vent variations. This is because its elevated position better catches the wind. There is also a non-motorized fan that is powered by wind flow, and which acts as an extractor fan.
A soffit vent is another variation. They are better protected from rain and leaks, but there is also better protection from wind, which can impede ventilation to a certain extent.
6. Install Passive Ventilation Vents on the Wall
If the windowless room has an exterior wall, then you should consider installing a passive ventilation vent.
They are typically louvered vents, which provide some control over the air entering the room. In addition, because they insert directly into the wall, you don’t have to worry about all the ductwork involved in venting to the roof.
However, putting in a passive vent on one side of your house means the wind direction plays a much larger role in the provided ventilation in comparison to a vent on the actual roof.
Furthermore, trees, houses, walls, etc., will all affect the amount of air flowing past the wall vent, thereby influencing the effectiveness of the vent.
7. Make Use of a Fireplace for Ventilation
If you have a fireplace in the windowless room, achieving natural ventilation is as simple as opening the fireplace damper, which should vent to the outside of the house.
While this is a less effective form of natural ventilation than that which a window would supply, it does meet the requirements of proper ventilation. Fresh air from outside can flow down the chimney into the room, and old air can leave the space in the same way.
To make this form of ventilation more effective, you can keep the interior door or doors open or install a fan. Anything that causes the air to circulate within the room will encourage an exchange of air with the outside through the fireplace chimney.
Of course, you will also have a cold draft coming into the room, which is not always ideal.
Problems With Fireplace Ventilation
There are some drawbacks to using your fireplace chimney for ventilation.
Firstly, when it is in use, it will not serve this secondary function as successfully. At the same time, more gases, etc., are being released into the room, making ventilation even more important.
Secondly, if your damper is always open, then you will have to choose between ventilation and a dry room whenever it rains. If you happen to be away from your home when it starts raining, then you won’t have a choice!
Thirdly, debris can fall or be carried into the room, and even animals can use it as a way to enter your house.
8. Install a Ventilation Grille in the Door
Suppose your windowless room has an exterior door, but this cannot be left open to aid with ventilation because of security or privacy reasons. In this case, you should consider installing a ventilation grille into the door or replacing it with one that already has a grille.
The benefit of this ventilation option is that there will be a direct exchange of air between the inside of the room and outside, as opposed to a vent that leads to a duct or another internal room.
Even though it will not be as effective as a grille in an exterior door, you can still install a ventilation grille in an interior door. However, this will only be a worthwhile option if the other room is well-ventilated.
9. Install a Ventilation Fan Between Two Rooms
Another option you can consider, especially if your windowless room does not have an exterior wall, is the installation of a ventilation fan(Amazon) between the windowless room and the adjoining room.
As with the interior door ventilation grille, this is only a viable option if the adjoining room is well-ventilated itself. Otherwise, you are exchanging stale air for stale air, and there is no actual ventilation occurring.
You can set up the ventilation fan so that it exhausts old air from the windowless room and rely on the negative pressure created to draw fresh air into the room. Or, you could set it up so that it pumps fresh air from the other room into the windowless room, relying on passive egress of old air down the created pressure gradient.
10. Direct Air From a Ventilated Room Using a Floor Fan
It is a common misconception that a fan can provide ventilation in a closed room. The fan certainly creates airflow, which helps the room to feel less stifling for the occupants. But ultimately, it does not ventilate the room according to the definition, i.e., supplying new air and removing old air.
However, there is a way to use a floor fan to provide ventilation to a windowless room.
If you place the fan in a well-ventilated adjoining room and angle it so that it blows into the windowless room, then it can create ventilation for that room.
You should place the fan a foot or so away from the doorway into the windowless room (depending on how powerful the fan is). If you put it in the doorway, then you are more likely to circulate the air within the room instead of encouraging the air to move in and out of the room.
Obviously, this is only an option if the windowless room can have the door open permanently. Furthermore, it is not an appropriate option if the windowless room is used for anything that could release large amounts of moisture or fumes.
11. Turn on the Ceiling Fan in the Adjoining Room
Like the floor fan, a ceiling fan in a well-ventilated room can also create enough airflow to create some level of ventilation for an adjoining windowless room.
As the ceiling fan is less directional than a portable floor fan, it is slightly less effective and should probably be used in conjunction with another method.
Once again, the door into the windowless room will have to remain open permanently for this to be a workable ventilation solution, and it is not sufficient if the room is used for moisture- or fume-generating activities.
12. Use a Range Hood
There are two ways in which you can use a range hood to ventilate a room without a window.
Firstly, you can install a range hood in the windowless room and vent it outside. However, unless you particularly need the range hood for the other functions it provides, then it would be cheaper to simply install a regular exhaust fan.
Secondly, you can turn on the range hood in an adjoining room.
For example, if you have a windowless pantry and it’s starting to smell a little bit stale, then you can leave the door open and turn on the kitchen range hood to create air circulation that will hopefully move air into and out of the pantry.
This is a ventilation strategy that would better serve as a support to another method. Additionally, running a range hood will create a lot of noise pollution, so you are unlikely to run it for very long.
13. Turn on the Dryer
If you keep your dryer in the windowless room, then when the dryer is on, it can serve to ventilate the room, but only if it vents to the outside.
To dry your clothes, a dryer pulls air into itself from the room, heats it, and runs it through your clothes. The hot air causes water to be drawn out of the material and suspended in the air. Finally, the dryer exhausts the hot and moist air to the outside.
The loss of the air to the outside creates a negative pressure gradient, like an exhaust fan, so fresh air is pulled into the room through any doors, vents, cracks, and holes.
This is a good option if you wish to have the dryer in the windowless room. If you do not, then it becomes a very expensive extractor fan that costs more to install and run than a regular exhaust fan.
14. Run the Whole House Ventilation System
If you have a whole house ventilation system that does not include a vent into the room without a window, you can still create a degree of ventilation in this room by turning up the house ventilation system.
This is because it creates a constant movement of air through the house, which will affect the windowless room, although only if the door to the windowless room is kept open.
Alternatively, you can investigate the option of adding a vent from the main house ventilation system into the room. This is a lot less invasive than installing a whole new duct system. You will just have to make sure that doing this alteration does not violate any building codes.
15. Build With Ventilation Bricks
Suppose you are renovating your house or working on a new construction project, and you know that a room is not going to have a window installed in it. In that case, you can provide for its ventilation by placing ventilation or air bricks at intervals in the wall.
Just remember that air bricks are only effective if they remain exposed. If you are planning to plaster a wall, then make sure you don’t accidentally block up the holes in the bricks.
Ventilation bricks are good because it provides a direct exchange of air between the windowless room and the outside. However, they have the disadvantage of always being open. You cannot shut them against the elements.
Bonus Tip: Room Layout
All of the ventilation techniques that we have described above function much better in a well-organized room. Clutter and tall furniture create pockets where air can get trapped and become stale.
Make sure that the air in the windowless room can move easily around the room and particularly that the air has a clear path to the vent, door, or other point of egress.
Related Article: Are Ridge Vents Required by Code
Sources
https://www.plumbworld.co.uk/blog/everything-you-need-to-know-about-bathroom-ventilation
https://codes.iccsafe.org/content/IRC2018/chapter-15-exhaust-systems
https://www.homebuilding.co.uk/advice/ventilation
https://www.hgtv.com/design/remodel/interior-remodel/ventilating-your-basement
https://www.ncbi.nlm.nih.gov/books/NBK143277/