VENTILATION :It is a process of introducing and circulating fresh air in a room in order to get rid of undesirable gases and replace fresh air.

Reasons for sufficient ventilation in the room

  • to prevent humidity that on high concentration of moisture in the air that causes a stuffy feeling that causes drowsiness,
  • to remove excess/surplus heat from people and machinery that makes working atmosphere uncomfortable.
  • to allow free circulation of air hence reduce bacteria and viruses concentration and prevent spread of airborne diseases e.g influenza (common cold) and T.B.,
  • to remove odours that develop when people are crowded,
  • to get rid of pollution in a room e.g smoke, aerosol, sprays, dust, gases e.g CO2, Co and starch from decayed matter.

Dangers of poor ventilation in a room

  • Suffocation and fainting

Occurs when people are overcrowded in a room.  They use up all fresh air.  May also be as a result of burning fuels e.g charcoal/coal in a poorly ventilated room.  Overcrowded people uses up all the air in the room then released carbon dioxide gas that causes fainting, suffocation and death.

  • Drowsiness

It is as a result of much humidity in the air/ O2 not being enough for breathing Discomfort

Occurs because of a room being excessively not due to heat from people and machinery.

It can also be due to bad smells on excessive humidity that make it feel stuffy and  uncomfortable.

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Easy transmission of communicable diseases

The room that has poor ventilation has a high bacteria and virus concentration that can be passed from one person to another.

Ways of ventilating a room

  • natural means
  • mechanical means


e.g          (i) use of windows

  • chimneys
  • vents
  • doors

 Using windows to ventilate the room They may be wooden, glass and metal.

The design of windows used include:

  • Louver windows

They open simultaneously. They let in fresh air and prevent raindrops from entering.

  • Fanlight windows:
    1. Are small windows normally fixed high up on walls of toilets, bathrooms and stores,
    2. Thy open towards outside,
    3. Are supported by a catch at centre
    4. May be left open at night if fitted with burglar proof bars.
  • Vertically pivotal windows
    1. they open vertically,
    2. half of window open towards the inside the other half towards outside, – can be modified to open towards outside only,
  • horizontally pivoted windows
    1. they open horizontally
    2. half of it opens towards outside
    3. the other half towards inside
  • Gliding windows

Open by gliding from side-side

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 Using doors to ventilate a room

  • may be from wood, glass/metal
  • they are of various types

e.g       – single shuttered

  • double shuttered
  • gliding or sliding doors

How windows and doors are used for ventilation

  • Adjacent method
    1. Two/more windows are placed on adjacent walls,
    2. They allow fresh air to move in slowly to replace stale one so refreshen the room,
  • Cross method

–    ventilation devices e.g windows and doors are placed opposite;

NB:- they should not be directly opposite because they allow a lot of air to rush in and out, that causes of doors and windows,


e.g       (i) fans

(ii) air conditioners

The two supplement the natural means of ventilation


  • they are normally fitted with rotary blades,
  • operated by electricity
  • when set into rotation they set air inside the room into current,
  • they keep air in the room in motion therefore achieving ventilation,


  • free standing
  • table top
  • ceiling
  • wall mounted

they only keep air in a room in motion so never remove stale air and replace it with fresh one; so they should always be used with other natural methods of ventilation.

Air conditioners

  • Are used in large building that have poor position for natural ventilation,
  • This device absorb stale air form inside of a room and replace it with fresh cooled air, NB:
  • They are fitted through a wall for part it can be inside and the other out,
  • They are more expensive to install and run than fans so not commonly used in homes.




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