What is natural ventilation?
Ventilation is the flow of outside air into a building and vice versa. Passive ventilation is when this happens without extract fans or similar devices, which are expensive. Effectively passive ventilation is provided by strategically opening and closing vents or windows using simple and inexpensive actuators. Outside air then naturally flows into a building.
Ventilation is essential for providing fresh air for breathing, removing airborne pollutants and odours from a building and controlling excess humidity.
Single sided ventilation
Rooms with windows on one side only. Cold air will stream in, and warm air will stream out again through the same window. This kind of ventilation is normal and generally practised, but it is only useful up to a certain room depth.
Single sided double opening
An advancement of the single sided principle provides a double opening, which is considerably more efficient.
Cross Ventilation
In the case of cross-ventilation, (windows open on both sides of the room/building) the pressure difference is used between the side of the building facing the wind and the side away from the wind. The positive pressure on the windward and/or a vacuum effect on the lee side of the building, causes air movement through the building from the windward to the lee side. In order to obtain the optimal airflow with minimal draught, the windows on the windward side are opened less than on the lee side.
Stack Ventilation
In a similar way to smoke ventilation, the natural buoyancy of hot air is used to allow venting through high level vents. Replacement fresh air enters from the lower vents. An advancement of this system is via a double façade. This works on the same principle as above (utilising both cross and stack ventilation) but also offers an ideal solution when the building is adjacent to roads and areas of high acoustic emissions.
Passive Cooling
Floor slabs can absorb heat build-up during daytime usage through a combination of solar gain, electronic equipment and user occupancy. As the external temperature drops at night, the building can be cooled by partially opening the vents around the building - often called night-cooling or night-purging. The example shown below uses an atrium design (utilising stack and cross ventilation) for this effect.
Advantages of natural
ventilation include
- Creation of healthy room conditions.
- Prevention damage caused by high
moisture levels.
- Natural ventilation is less expensive than
air conditioning.
- Reduction of energy consumption and
operating expenses.
- Low repair and maintenance expenditure.
- Increase in value of property.
- Positive image for companies by.
moisture levels.
operating expenses.