The implementation of the EPBD recast puts increasing pressure to achieve better building and ductwork airtightness since for most European climates and countries, good airtightness levels are necessary to achieve nearly zero-energy buildings. This has been shown in a number of studies with energy impacts of the order of 10 kWh per m2 of floor area per year for the heating needs in a moderately cold region (2 500 degree-days) and 0 to 5 kWh/m2/year for the ducts plus the additional fan energy use . For more information see also the ASIEPI project technical report on building and ductwork airtightness as well as REHVA journals’ special issue on airtightness .
G. Guyot, F. R. Carrié and P. Schild, “Project ASIEPI – Stimulation of good building and ductwork airtightness through EPBD,” 2010.
 R. Coxon, “Research into the effect of improving airtightness in a typical UK dwelling,” The REHVA European HVAC Journal-Special issue on airtightness, vol. 50, no. 1, pp. 24-27, 2013.