This European standard describe the method to calculate the ventilation air flow rates for buildings to be used for applications such as energy calculations, heat and cooling load calculation, summer comfort and indoor air quality evaluation. The ventilation and air tightness requirements (as IAQ, heating and cooling, safety, fire protection...) are not part of the standard. For these different applications, the same implicit method is used but the input parameter has to be selected according to the field of application. For some applications explicit calculations are also defined in this standard. The method is meant to be applied to : Mechanically ventilated building (mechanical exhaust, mechanical supply or balanced system). Passive ducts. Hybrid system switching between mechanical and natural modes. Windows opening by manual operation for airing or summer comfort issues. Automatic windows (or openings) could be considered at a later stage. Industry process ventilation is out of the scope. Kitchen where cooking is for immediate use are part of the standards (including restaurants..) Other Kitchens are not part of the standard The results provided by the standard are the building envelope flows either through leakages or purpose provided openings and the air flows due to the ventilation system, taking into account the product and system characteristics.