VPE 511: Environment and Environmental Hygiene (2+1)

TYPES OF VENTILATION

• There are broadly two types of ventilation
  • Natural
  • Mechanical

Natural ventilation

• Natural ventilation is the simplest system of ventilation which depends on three forces such as wind, diffusion and inequality of temperature.
• Broadly three types of natural ventilation are in use;
  • A fixed open ridge with a protective cap is sufficient in climatic housing for cattle
  • A simple chimney type of insulated flue is satisfactory for a limited area of controlled outlet ventilation.
  • Hopper type windows fitted with gussets to prevent direct draughts serving as principal inlets and small baffled openings left open during cold or windy weather.

Mechanical or artificial ventilation

• Mechanical or artificial ventilation can be effected by four means;
  • Exhaust ventilation: air is extracted to the outside from the inside by an exhaust fan operated electrically
  • Plenum ventilation: fresh air is blown into the room by centrifugal fans so as to create a positive pressure and replace the ventilated air proportionately.
  • Balanced ventilation: this is a combination of exhaust and plenum system of ventilation.
  • Air conditioning: it is the simultaneous control of all factors affecting both physical and chemical conditions of atmosphere within a structure.