There are different ways in air conditioned characteristics selection and approach, following the specific application (domestic, office, industrial or technological. For each practical situation, there are designed special parameters, defined on the application necessities, climate conditions, field dimensions, temperature required, thermal losses etc. In domestic application, field studies demonstrate that there are substantial numbers of not-satisfied people in many buildings, among them those suffering from Sick Building Syndrome symptoms, even there are established special standards and guidelines to comply. Based on existing information and on new research results, five principles are suggested as elements behind a new philosophy of excellence: better indoor air quality increases productivity and decreases Sick Building Syndrome (SBS) symptoms; unnecessary indoor pollution sources should be avoided; the air should be served cool and dry to the occupants; "personalized air", i.e. a small amount of clean air, should be served gently, close to the breathing zone of each individual.