Currents trends in indoor air quality involve prevention as well as the need for specific legislation (norms) to protect people's health and to achieve greater levels of comfort. It is currently one of the most important areas of study [5,6, 10]. The existence of different indoor air quality norms and standards depending on the country involved has made it difficult to determine when these standards really ensure low levels of indoor pollutants. The requirements of the future European ventilation norm (prENV 1752) make a detailed study on the energy implications of the problem essential. This work represents an original study in this field, where the results obtained from a series of practical indoor air quality and ventilation measurements are explored. These results have been obtained using photoacoustic spectroscopy (PAS) and the trace gas (sulphur hexafluoride) technique in a series of Spanish office buildings with varying climatisation systems. The results obtained in ventilation flows as well as an analysis for comparison purposes with data on Spanish, American (ASHRAE 62R) and European norms (prENV 1752) are presented. The conclusions which may be drawn are also offered. Finally, the work shows a ventilation flow which achieves high environmental indoor air quality in offices while at the same time offering compatibility with high energy saving.