The principle of natural ventilation in a building is to rely on natural physical phenomena rather than mechanical systems to renew air within.
The air circulation can also be generated by the pressure differences that exist between the various facades of the building due to external wind and/or by the thermal draught produced by the difference in density of air according to the temperature gradient.
Choosing this type of system is particularly popular during periods when the outdoor air temperature is high enough not to be too large and low enough to be able to dissipate the energy of the buildings while maintaining acceptable thermal conditions within it.
The operational system needs however a control over the positon and the size of the openings and vents set up on the building envelope (facades, roofs, double skins.) … These parameters are indeed of primary importance to achieve the desired renewal rates in order to dissipate energy in the building while ensuring that the generated air flow (draughts) will not be likely to interfere its users.
It is also often necessary to ensure that the air renewal rates are sufficient to meet the health standards and to verify the positive potential impact of wind on the performance of the system.
Computations carried out by the company OPTIFLOW allow to answer all these questions. They can accurately quantify the obtained ventilation rates and the associated thermal comfort in the different climatic reference situations. They present themselves as a necessary support to improve the size and the position of the elements at the inlet and to be sure that the extraction of the air reconcile the comfort of people and energy building performances.