Question about draft (probably wind blowing up in your room)

[Physicsissuef]

Hello!

I have one mysterious question. I have room 25 m², and I want to made draft, by opening one window and my door to be closed, so I will have closed space with only one window open. What is actually draft? Is it same with wind? Draft = circling of hot and cold air?

Thank you.

 

[Astronuc]

A draft is basically a very light or gentle wind. In the context of a home or building interior, it refers to air flow which may result from a wind (external) or some pressure differential within the home/building or room.

It could also be a manifestation of natural convection where cooler or drier air displaces warmer or moister air, i.e. denser air displaces less dense air.

A draft could also be caused by forced convection, i.e. the air flow from a fan.

 

[Physicsissuef]

So, with opening one window in normal circumstances, I could cause a draft? Why some people say that I must open the window from other room, to open my door, and to open the window of my room to cause draft?

 

[Astronuc]

It depends on a number of conditions, e.g. if the air outside is still and at about the same density and pressure as the air in the room, then one will likely not have a draft in the room. If air outside is cooler than inside the room, one can make a small opening in the top and bottom of the window, and the cooler outside air would flow into the room while the warmer air would flow out, and that would cause some draft as the air convects by natural circulation.

If the wind is blowing, the opening a window may cause a draft in the room, especially if the house/building is not air-tight.

 

[Physicsissuef]

Lets say that the air outside is cooler than inside the room, can I make draft only with opening one window and the door of my room to be closed? Why people say that there must be two windows from two different rooms to make draft?