European projects on ductwork quality

This paper presents results from European Union projects on ductworlk quality tightness. The projects were done in Sweden, Belgium, and France. The tightness on a large number of ductwork installations in the three countries was compared and it was found that there is a tremendous difference in tightness. The answer to the question : "Why this large difference between the countries ?" is most probably that Sweden has been requiring tight ducts, i.e., specifying how much they are allowed to leak at a certain test pressure, whereas in the two other countries, tightness of ductwork is normally neither required or tested.