The relative importance of ventilation in the energy balance of buildings has been increasing,as a consequence of control of heat exchanges through the envelope and internalgains. It is therefore very important to clearly understand the main factors that affect energyconsumption due to ventilation and potential ways to decrease the energy demand withoutaffecting IAQ.This study was developed within the European project TIP-VENT (JOULE). An analysiswas made to study the impact of the following issues: (1) ventilation rates mandated byregulations and standards in Europe; (2) ventilation control strategies; (3) fan power consumption;(4) Other issues such as heat recovery and air tightness of the building envelope.The methodology consisted of computer simulation using mainstream programs such asESP-r and Visual DOE as well as other more specific tools. Six real buildings were selectedas case-studies: An hotel, an auditorium, an office building, a single-family dwelling, anapartment and a large office building. They were all simulated in a mild, a moderate and acold climate.Results show that the energy impact of the different minimum ventilation rates stated inregulations in different countries can be large. They also confirm the large potential energysaving by using variable ventilation (e.g., CO2 controlled) and free-cooling. In terms of fanpower consumption, the energy saving potential is also very large. Combining several techniques,it is shown that, in many cases, a best system can allow an energy saving of up to70% over a common system.