All this being convinced that the outside air is better than the one we are going to replace , but often technical investigations tell us the opposite. The new technologies dedicated to saving energy and to living well-being see a different way of interpreting the word “air” in the new system of controlled mechanical ventilation. Filtering the exchange air and retrieving from it the maximum thermal energy to reissue in the environment is now possible with the new projects of heat engineering , raising the personal well-being and creating an added value to the property estate which is equipped with rationalisation of consumption systems, a must-have in the era of sustainable consumption and reduction of operating expenses. The new thermo-technical design that responds to the European Directive 91/2002 has shown the way for the use of high- efficiency energy systems that provide a tangible contribution to the well-being of ourselves as we support costs for the daily management of our services.