Window ventilators enable air supply to particular rooms. Even when windows are closed tightly fresh air necessary for efficient ventilation is supplied.  A standard set includes an internal part (window ventilator), which regulates the amount of supplied air as well as the external part (eaves), which provides protections against rain and insects.  Additionally, special joints and eaves providing additional sound insulation may be installed.
Ventilators are mounted in the top part of the window. This results from provisions of the applicable Polish standard as well as practicality. Fresh air from the outside flows above members of the household; this prevents unpleasant draught effect and users' discomfort.

Window ventilators are mounted in rooms and optionally in the kitchen, subsequently the air flows through the entire apartment to rooms equipped with ventilation ducts (kitchen, bathroom and lavatory) from where it is removed outside along with impurities. 

Ventilators are divided into the following categories based on their operation meth

• ventilators controlled by humidity sensor - controlled automatically, amount of supplied fresh air depends on the relative humidity in a given room. The higher the humidity the more fresh air is supplied. Air supply depends on the time of day as well as intended use of a given room (e.g. at night-time more air is supplied to the bedroom and during the daytime to the living room).  Control sensor is made of a bundle of polyamide tapes. One may choose to close the cover in order to reduce the air flow to the minimum.
  
  

  
  ventilator controlled by humidity sensor EMM

  
  ventilators controlled by humidity sensor EHA

• Pressure ventilators - automatic control, amount of supplied air depends on the pressure difference between outside and inside of the room.
  The process continues to the point, where ventilator efficiency reaches its maximum value.
  Further increase causes blade to draw back reducing the amount of supplied air. This might happen in the event of e.g. gusts of wind.  One may choose to close the cover in order to reduce the air flow to the minimum.

  
  pressure ventilator EFR

  
  pressure ventilator 2MO

  
  pressure ventilatory AMI

  
  pressure ventilator AMA

• Manually controlled ventilators - the user controls the amount of air supplied by opening/closing the cover.