Opening the upstairs window relaeases room hot air then cooler air can come in from an open window down stairs. That doesn't mean the air that is coming in is cool, only cooler. Opening the upstairs windows and some of the downstairs windows will allow for a breeze and airflow through the house.
The idea to keep in mind is that hot air rises. Therefore, if you open windows in the downstairs area where the cool or shady side of your home is, this will allow cool air in. At the same time, open windows on the upstairs (if applicable) portion of your home where the sun is still hitting.
The short answer is yes, sleeping with an open window is dangerous, especially if it's an easily accessible one. Open windows are like an open invitation to any burglar in the vicinity.
Opening the windows simply lets cool air escape and hot air to enter, resulting in hotter interiors. Before deciding to open all your windows at home during hot weather, grab a thermometer, and check if it's hotter outside the house. If it's cooler indoors, just close your windows.
Heat hovers at the ceiling. By opening your double-hung windows about three inches at the top and at the bottom, the hot air can escape out the top of the window and the cooler air can enter through the bottom.
To increase ventilation in your home, you can: Open windows and screened doors. Do not open windows and doors if doing so poses a safety or health risk to children or other family members (e.g., risk of falling or triggering asthma symptoms). Operate a whole-house fan, or an evaporative cooler, if your home has one.
The single most effective way to avoid Carbon Dioxide build-up is to keep windows open while you sleep. This allows fresh oxygen in, as well as allowing Carbon Dioxide to escape naturally. Another important factor in choosing to keep windows open at night is for temperature control or thermoregulation.
“Generally, when it is really hot outside it is a good idea to keep windows closed during the daytime, as you don't want the hot external air to come into the house warming it up. However, after the sun goes down, the outside air will start to cool down,” Browning explains.
Open some windows and feel if you can start to create a breeze. Open a lower window from the cooler side of your home and an upper window from the hotter side of your home.
Finally, if you can handle it, leaving the slightest opening in your window overnight will make the air circulating your room more comfortable. Yes, you will be losing some energy, but the health benefits you get from bringing fresh air into your home is unparallel and most definitely worth it.
Sleeping with an open window can negatively impact your health as well. While cold air itself can't make you sick — colds and flus occur because germs overwhelm a person's immune system — it can potentially dry out nasal cavities, resulting in increased mucus production and a possible sinus infection.
"However, after the sun goes down, the outside air will start to cool down. At this point, it is a great idea to open the windows to let in a breeze of cool external air into the bedroom, helping cool the room and to provide needed air circulation."
In addition to cooling efficiency, leaving the windows open will also put stress on the air conditioner. This is because the open windows let warm air inside. This extra stress may cause the air conditioner to become faulty prematurely.
If the air inside your home is never exchanged for fresh air, it can become stale. When you're inside a building that's tightly sealed, without much ventilation, for much of your time, it's called sick building syndrome, or SBS. Living in this type of environment can allow toxins to build up in the house.
Prevailing wisdom is that at least 5 minutes—and ideally 15 to 20 minutes—a day of ventilation significantly improves indoor air quality. For a strong ventilation, open the front and back door, along with windows on the path in between, to get the baddies out.
Dr Shea agrees that the time for open windows is overnight. “You can get apps which will tell you the temperature [inside and outside], so you can figure it out more scientifically, but at night-time, you could quite readily throw the windows open and get some cool air in.”
One of the best ways to keep humidity from entering your home in the summer is to keep the doors and windows tightly closed.
More significantly, open windows affect the efficiency of a building's air-conditioning system, which might explain why unopenable windows are most commonly found in brand-new hotel towers resembling corporate office blocks.
You might notice that your nose runs more often or that you get stopped up overnight. Itchy, watery eyes; sore throats; and skin rashes can all result from inadequate fresh air. These symptoms can have other causes, of course, which is why we recommend a professional inspection.
15 minutes is enough to air the house properly
It will take just a few minutes to heat the room again. Leaving a tilt-and-turn window ajar all day, however, is not effective: it cools the walls and it costs much more to heat the room back up again.
Sleeping in a cold room is okay as long as you're comfortable with the temperature. If you're healthy, the crisp air is unlikely to make you sick. Instead, sleeping in a cold room has many benefits like reduced insomnia symptoms, better melatonin production, and deeper sleep.