All three regions of Belgium (Brussels, Flanders and Walloon Region) have from the start of the energy performance legislation the airtightness of buildings in their regional Energy Performance (EP) regulations. Airtightness testing is not mandatory and there are no minimum requirements; However, when using the result of an airtightness test instead of the default air permeability value (for heating calculation) 𝑣̇50 = 12 m³ / (h.m²), a substantial improvement in energy performance can be achieved.

Since January 1 2015, it is mandatory in Flanders to be qualified to perform such tests in the context of the EPBD regulation. The qualification procedure involves the successful completion of a theoretical exam as well as a practical test. There are currently more than 200 testers qualified to realise pressurization tests.

In order to guarantee the quality of the test results and the reliability of the declared airtightness levels, 2 types of control are foreseen:

• 10% of the submitted declarations are subject to a desktop control, in order to check if the reporting is complete and correct
• 10% of the tests have an on-site inspection.  In order to allow this procedure, qualified testers have to communicate when the tests are carried out. Part of these tests involve an a-posteriori control. The tester must at the end of the test report by SMS the declared airtightness result. The control organisation will then be within 15 minutes after the confirmation on site whereby the tester must redo the test.