Yes, provided that the building is equipped with an appropriate ventilation system (whether natural, mechanical or hybrid). A French study mentioned in the AIVC newsletter n°2 shows that better building airtightness converges with better indoor air quality because the ventilation system operates more efficiently. Building leaks cause uncontrolled airflows and potentially poorly ventilated rooms although the total building air exchange rate may be sufficient .
 L. Mouradian and X. Boulanger, “QUAD-BBC, Indoor Air Quality and ventilation systems in low energy buildings,” AIVC Newsletter No2, June 2012.
Duct leakage is not only detrimental to energy efficiency, but also indoor air quality (in terms of lower air change rates and ventilation efficiency in rooms), comfort, and fire protection. It is often accompanied by other problems, such as inferior commissioning and cleaning. In Scandinavia good ductwork airtightness has largely been promoted together with indoor air quality benefits. Note that the Swedish VVS AMA guideline not only deals with energy issues related to duct airtightness but also with safety and indoor environment. 
 G. Guyot, F. R. Carrié and P. Schild, “Project ASIEPI – Stimulation of good building and ductwork airtightness through EPBD,” 2010.
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