Indoor Air Quality (IAQ) - General Standards, legislation and regulations in force. The purpose of ventilation in confined environments to maintain the IQ (norms and criteria of choice). Legislation on Predictive Maintenance of Air Conditioning Systems. VMC in residential area. Air filtration - product regulations in place in relation to quality and energy aspects. Active electrostatic filtration - Peculiar features of the solution. Presentation and discussion of the new Norm UNI 10339 Rev. to the completion of the European Standard UNI EN 13779/2008. Presentation of standards currently under revision on ventilation issues (EN 16798) and air filtration (ISO 16890). Examples of applications in the design of new buildings or retraining of existing ones. Performance Method and "IAQ Calculation" Software (according to current norm). Energy analysis and relative return on investment - Comparative between active electrostatic system and medium mechanical system.