How to Ventilate Well


As a specialist in air and air conditioning, Daikin happily provides you some tips on how to ventilate your house for healthy and confident daily life.

1. Basic Knowledge of Ventilation

2. Tips on Ventilation

1. Basic Knowledge of Ventilation

What is ventilation?

Ventilation is the replacement of indoor air with fresh outdoor air in order to dilute and displace the air pollutants (substances that are harmful to humans) inside a building.

What are pollutants?

Pollutants (substances that are harmful to humans) include carbon dioxide (CO₂), carbon monoxide (CO), formaldehyde (HCHO), house dust, pollen, bacteria, and viruses that exist in the air of a room.

Ventilation can be expected to dilute these pollutants and displace them from the room.

Why do I have to ventilate?

① Because ventilation dilutes and displaces pollutants in the air of a room

In a completely closed room, air cannot easily leave the room, causing air pollutants to remain and increase in the room. This situation can impact the health of the people in the room.

Ventilation is extremely important for diluting and displacing these air pollutants.

② Because dirty air accumulates in a room with no ventilation

Many of the residences where you live such as houses and condominiums have a high level of airtightness, and dirty air cannot easily leave the room. When nothing is done in these types of residences, there will be insufficient ventilation, and dirty air will increasingly accumulate in the room.

Can’t I use the air conditioner to ventilate?

Many people mistakenly believe that air conditioners bring air from outside the home and that this air is used to ventilate the room. In fact, air conditioners commonly used in residences creates a comfortable environment just by drawing air from INSIDE the room, cooling or warming it, then returning that air back to the room.

Indoor air is not replaced by fresh outdoor air.

In most cases, air conditioners cannot perform ventilation.

You must ventilate in another way.


2. Tips on Ventilation

What needs to be done for ventilating the house?

① Opening the windows and creating an air passage

The standard length of time and frequency to ventilate a house by opening windows is about 5-10 minutes per hour.

However, the speed in which air is discharged outside a building varies depending on such factors as window size, area of the room, and type of pollutants floating indoors. For this reason, it is difficult to accurately determine ventilation effectiveness and the degree to which ventilation can reduce the risk of infectious diseases.

Also, the effect is higher when ventilation is performed twice an hour for five minutes than when it is performed once every two hours for ten minutes.

Consequently, the more often you ventilate your house, the greater improvement you will see in ventilation effectiveness.

For those worried about pollen when ventilating with an open window, placing an air purifier near the window is somewhat effective in keeping pollen from entering the room. Lace curtains are also an effective measure against pollen.

Method for opening windows

Method for opening windows to create an air passage

When ventilation is performed by opening windows, it is better to open two windows instead of one in order to create an air passage for efficient ventilation. It is even more efficient if the two windows are diagonal to each other.

Good example:

It is efficient to open windows
that are diagonal to each other.

Opening two windows positioned

Opening two windows positioned closely to each other will prevent air from flowing through the entire room.

Bad example:

Inefficiency results from opening
nearby windows due to the small area
in which air circulates.

difficult for a breeze to flow
For difficulties in letting a breeze inside even when windows are open

Wind and air tend to smoothly enter a room through small gaps while easily leaving a room through larger gaps (with a small force). If you find it difficult for a breeze to flow into a room, try opening the window supplying air only a narrow distance while opening the window discharging air a much wider distance. This will increase ventilation efficiency.

When it is difficult for a breeze to flow
into the room, adjust the width
that the window is opened
(so that a little can discharge a lot).

rooms with only one window
For rooms with only one window

When there is only one window, it is effective to open the room door and place a fan or similar device near the window.

The most effective method is to turn the fan toward the window and let air outside the room. If the fan is directed toward the room, even though fresh outdoor air will enter the room through the window, the dirty air in the room will remain inside.

For a room with only one window,
place a fan toward the window
to create a breeze.

rooms without window
For a room without a window

When a room has no windows, you can open the room door and place a fan or similar device to enable the flow of air outside the room. The air from other rooms is also effectively discharged outside the house by operating a ventilation fan for a bath, lavatory, or toilet.

Ventilation method for a room without a window

  • Room without a window
  • Ventilation fan

② Using the ventilation fan in the kitchen

Using the ventilation fan

Operating a kitchen ventilation fan can be especially effective since it can discharge the largest volume of air among all the ventilation fans installed in the house. Try opening a window located as far away as possible from the kitchen to ventilate the entire room effectively. Even when two windows are available, the kitchen ventilation fan can still assist in ventilation. For this reason, we recommend using the kitchen ventilation fan in addition to opening windows.

Summary of Home Ventilation Methods

Summary of Home Ventilation Methods
Depending on your living environment, you can combine the two ventilation methods explained above:
  • Opening the windows and creating an air passage, and
  • Using the ventilation fan in the kitchen. Knowing these methods will enable you to perform efficient ventilation of your home.

Ventilation example for a typical apartment

Want to ventilate the entire room?

Open the windows on the entrance side and balcony side, and be sure to open the doors along the air passage.

Want to ventilate the living room? (when you cannot open an entrance window)

Open two windows facing the balcony.

  • No breeze will enter or leave when only one window is open, so be sure to open both ends to allow air to flow.

The balcony windows should be opened at two places (both ends).


If a breeze does not flow into the room even when the windows are open, operate the kitchen ventilation fan (for the range hood) and open the balcony window farthest away from the ventilation fan.

Operate the kitchen ventilation fan and partially open the window facing the balcony which is farthest away from the kitchen.

Daikin, as a company that provides solutions with air, will continue to bring comfortable air and confidence to customers around the world while pursuing the new possibilities of air and conveying its importance.

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