This guide recently released by Encraft, provides guidance for the specific airtightness testing requirements for Passive House & EnerPHit certification, taking into account the existing differences in the calculations and methodologies when compared to the UK Building Regulations. It includes information on the testing protocol, the volume calculation and the test method.
The use of Passive House components in refurbishments of existing buildings leads to extensive improvements in thermal comfort, economic efficiency, absence of structural damage and climate protection. Achieving the Passive House Standard in refurbishments of existing buildings is not always feasible. Therefore, the Passive House Institute (PHI) developed the EnerPHit for certified energy retrofits which, based on Passive House principles, calls for high quality energy efficient components and ensures that both the energy demand as well as the quality are future-proof.
The guide is available to download at: http://www.encraft.co.uk/wp-content/uploads/2015/03/Airtightness-testing-for-Passivhaus-projects.pdf