One of the topics studied in the European IEE-ASIEPI project (www.asiepi.eu) is the way envelopeairtightness is dealt with in the EPB-regulations of the Member States. To this end, a number of surveyshave been made among the participating countries. Also a quantitative comparison on a samplebuilding has been performed. The results of this study are used in the development of an instrumentto compare the energy performance requirement levels among the Member States. The results illustrate that the different national EPB-calculation methods show different tendencies, revealing sometimes diverging underlying philosophies. Notably the concept and numeric figures of a default value are different, as well as the treatment of very good airtightness: in some methods the stimulus to do better than a certain threshold value becomes very small or is nil. In other countries, the incentive remains proportional all the way to the limit value of perfect air tightness. All these observations are illustrated and explained in the paper.