This paper presents results from European Union projects on ductwork 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 nor tested.

Units: SI