text: Natural ventilation harnesses naturally available forces to supply and remove air in an enclosed space. Poor ventilation in rooms is identified to significantly increase the localized moldy smell in specific places of the room including room corners. There are three types of natural ventilation occurring in buildings: wind-driven ventilation, pressure-driven flows, and stack ventilation. The pressures generated by the stack effect rely upon the buoyancy of heated or rising air. Wind-driven ventilation relies upon the force of the prevailing wind to pull and push air through the enclosed space as well as through breaches in the building's envelope.
  Almost all historic buildings were ventilated naturally. The technique was generally abandoned in larger US buildings during the late 20th century as the use of air conditioning became more widespread. However, with the advent of advanced Building Performance Simulation (BPS) software, improved Building Automation Systems (BAS), Leadership in Energy and Environmental Design (LEED) design requirements, and improved window manufacturing techniques; natural ventilation has made a resurgence in commercial buildings both globally and throughout the US.
  The benefits of natural ventilation include:
  *Improved Indoor air quality (IAQ)
  *Energy savings
  *Reduction of greenhouse gas emissions
  *Occupant control
  *Reduction in occupant illness associated with Sick Building Syndrome
  *Increased worker productivity
  Techniques and architectural features used to ventilate buildings and structures naturally include, but are not limited to:
  *Operable windows
  *Night purge ventilation
  *Clerestory windows and vented skylights
  *Building orientation
  *Wind capture façades