Ever since I was a kid I always wondered how people are not suffocating from staying in their house. Like if all windows are closed how does air get in? Wouldn’t we just breath up all the available air in a matter of hours and die? Same goes for cars too. If I’m on a long road trip and the windows are closed how am I still alive?
In: 2
If all the same air stayed trapped in a car for a long time it’s possible you could suffocate. However, the ac system takes some amount of outside air and your car isn’t perfectly sealed so it’s not a big problem. The answer’s pretty much the same for a house.
Neither the house nor the car are air tight. Air can get in from outside. So the air you are breathing is replenished from outside.
There’s a concept called partial pressures, where the effective pressure driving the flow of a gas can be calculated as the portion of the pressure that a single gas represents.
So, if indoor and outdoor pressures are similar, but oxygen concentration is lower indoors, a pressure proportional to the difference in concentration will force oxygen into the house.
This even applies when total pressure goes in the opposite direction. So, if 5% higher pressures inside, but oxygen concentration is 10% lower inside, even as air flows out, oxygen will flow in.
Both of them have plenty of places for air to circulate in and out. Windows and doors are not airtight.
First off I’m going to say that CO2 poisoning is extremely unpleasant and people will do anything to avoid it, long before death is even close. So …
Cars aren’t sealed and there is always some fresh air coming in.
Older houses leak, from doors, vents, windows, electrical outlets, etc. New houses build to much tighter standards, and can get stuffy if closed up for a long time, such as in winter. For those cases there are [air/heat exchangers](https://www.venmar.ca/air-exchanger.html) for houses which bring in warmed air from the outdoors and vent stale air from the house.
Windows tend to be pretty airtight but if you look at your doors you’ll probably see some spaces at the bottom where air is getting in. Garage door and front door are good examples.
Air also gets in through bathroom ventilators (the fan that runs when the lights are on) and most attics have open vents for dispersing heat build up.
Lastly you have your oven ventilator and the exhaust for your drier.
Air pressure differences inside vs outside move this between these spaces.
As other have said, neither of those things are airtight. And, on top of that, movies and tv drastically underestimate the time it takes for a person to run out of air in a sealed room.
[https://smartairfilters.com/en/blog/does-closing-the-windows-starve-us-of-oxygen/](https://smartairfilters.com/en/blog/does-closing-the-windows-starve-us-of-oxygen/)
One of the things builders are required to do now in some areas are blower door tests. This test basically tests how leaky your house is, how many air changes per hour your house does (This is outside air getting into your house and inside you have spent money to condition going outside). The more air changes per hour the less efficient the house is, so building science tries to seal up houses as much as possible to prevent that.
If you can build a really efficient tight house then you can use an air exchanger which takes the air you have already paid to heat or cool and then gives that energy to fresh incoming air before exhausting the old air outside.
Cars are nowhere near being airtight, if you have ever seen a video of a car going into a body of water it sinks because water is getting inside. If water can get in then air can get in even easier.
In a house or car, oxygen is constantly being replenished through the process of ventilation. This is the process of allowing fresh air from outside to enter the building or vehicle, and allowing stale air inside to escape.
In a house, this is typically done through windows, doors, and vents. The windows and doors can be opened to let fresh air in, and the vents can be used to circulate the air throughout the house. In a car, fresh air is typically drawn in through the car’s ventilation system, which uses fans to blow air into the car and circulate it throughout the cabin.
In both cases, the fresh air that enters the building or vehicle contains oxygen, which is then breathed in by the people and animals inside. As they breathe out, they release carbon dioxide, which is then expelled from the building or vehicle through the ventilation system. This process helps to maintain a healthy supply of oxygen inside the house or car.
Also to mention typically cars will have fresh air coming in from the HVAC system and there is usually a small flaper door in the bottom of a rear quarter panel to vent air out.
Latest Answers