Natural Ventilation

Buildings that are purely mechanically ventilated or air conditioned can suffer from a number of problems including, high energy consumption, poor indoor air quality and thermal comfort. However if a purely naturally ventilated solution is adopted it may be difficult to maintain the indoor environment within acceptable comfort limits at all times.

The basic philosophy is to open the windows and switch off the air conditioning to avoid the energy penalty and consequential environmental effects of year round air conditioning. Mixed mode systems are easy for occupants to use, the great majority of domestic houses operate successfully using mixed mode principles. There is also evidence of significant psychological and health benefits associated with naturally ventilating health facilities.

The basic philosophy is to open the windows and switch off the air conditioning to avoid the energy penalty and consequential environmental effects of year round air conditioning. Mixed mode systems are easy for occupants to use, the great majority of domestic houses operate successfully using mixed mode principles. There is also evidence of significant psychological and health benefits associated with naturally ventilating health facilities.

The temperate climate in many parts of Victoria will permit acceptable thermal conditions to be achieved for up to 40% of the year using a natural ventilation system.  The factors that improve the performance of a natural ventilation system are:

  • Performance of the building façade; size of windows, type of glass and shading system, the insulation performance of the building and air tightness;
  • Building form factors effect how well a building can be naturally ventilated;
  • Depth of building and distance between opening for cross flow ventilation and floor to ceiling heights (the taller the space the deeper it can be naturally ventilated);
  • Maximise exposed thermal mass (masonary) to the interior of the occupied spaces to absorb heat gains in to the structure, which may reduce the peak cooling load. This heat gain can be purged from the structure, using a night ventilation strategy;
  • Minimise internal heat gains; energy efficient lighting, flat screen monitors and energy efficient office equipment; and
  • Occupant Involvement so that the system is understood and easy to operate in its different modes.

Impact of Implementation

Retrofitting a mixed mode ventilation system may require the installation of openable windows or louvres in the building façade, together with a control system strategy which shuts off the mechanical ventilation / air conditioning system when the windows are open in natural ventilation mode. It could be uneconomic to retrofit natural ventilation systems in existing buildings which were designed to be air conditioned. Mixed mode ventilation can be easily incorporated as part of the design of new buildings. Automation of the operable windows/louvres could be considered

Natural Ventilation

Natural Ventilation

 

 

Source: UT Knoxville, Pinterest

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One thought on “Natural Ventilation

  1. Pingback: Efficient HVAC Systems | Energy Systems & Sustainable Living

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