Overall most of products are tested according to EN12114 (air permeability of building components) or EN 1026 (airtightness of windows) either internally or externally.
The most known way of certifying products is through Passive House Institute in Germany , the product, including installation manual, is sent to PHI Darmstadt, where THEY apply the product and assess it on its airtightness properties. A yearly fee has to be paid to maintain the certificate.
Another possibility would be to get a Komo certificate for the Dutch market (thus rather limited to Holland) or to go for quality stamps such as a Sintef approval (with some authority outside of Norway too).
There is also the MO01, a German directive written by IFT (Institut für Fenstertechnik) which enables to assess airtightness of perimeter joints around a window before and after ageing. The ageing is based on pressure, temperature and mechanical load.
 Passive House Institute. Components Database. Airtightness systems.
Posted in: Building Airtightness