This standard specifies the requirements for ventilation in buildings intended for human occupancy. The purpose of this standard is to ensure that ventilation systems are designed,constructed and can be maintained in a technical and hygenic responsible way considering comfort and energy efficiency.This standard comprises provisions for design, construction and testing and operation of ventilation systems. This standard applies for mechanical ventilation installations including the mechanical part of hybrid ventilation installations, which are installed permanently in buildings and have the main purpose to keep one or more indoor air parameters within close specified limits. The standard does not apply for installations which main purpose are to remove pollutions produced by industrial or similar prosesses, but it comprises ventilation systems which shall establish the necessary replacement of air. The standard does not apply to fire requirements to ventilation installations; reference is made to DS 428 Code of Practice for technical measures for fire protection in ventilation systems for buildings, when it applies for mechanical natural ventilation systems and the building regualtion, BR when it applies fornatural ventilationsystems.