Documentary and Feature Film Studio is one of the oldest film studios in Poland, located at ul. Chełmska 21 in Warsaw. It was founded in 1949, initially producing documentaries, but over time expanding its activities to feature films. Films were created there by, among others: Krzysztof Zanussi, Andrzej Wajda, Jerzy Łomnicki and Jerzy Hoffman. Currently, it is the largest film production center in Poland. Work in one of the plant's buildings included sealing the N1 and W1 installations. Air leaks were of similar magnitude in both installations. Class-free ventilation ducts after the sealing process using AEROSEAL® technology meet the requirements of tightness class B.