Increasing Sound Insulation of Window with Add-on Systems & Various Insulating Glass Unit Configurations


  • Joyce Mak Association of Professional Engineers and Geoscientist of BC British Columbia Building Envelope Council Seattle Building Envelope Council
  • Maureen Connelly BCIT


The acoustic performance of a building envelope is greatly dependent on the windows and other glazing elements. Windows represent a significant sound path for exterior noise to transmit into the interior space due to their relatively low mass. Replacement or upgrade of existing windows may be impractical due to heritage site, financial or investment considerations, and rental or condominium agreements. To combat noise infiltration in existing residential buildings, commercially available add-on systems can be incorporated to either the exterior or interior side of the windows.


This research describes results of sound intensity measurements of five types of window add-on systems and their potential to reduce sound transmission through a standard size residential unplasticised polyvinyl chloride framed window. The effects of different add-on systems were investigated on three types of insulated glazing unit (IGU), double pane, double pane-acoustic and triple pane.


All add-on systems exhibit frequency band dependent acoustic improvement from the baseline IGU. The add-on systems provide the most appreciable noise reduction when they are installed on the baseline double pane IGU, less increase performance on the double pane-acoustic and limited performance increase on the triple pane. In some instances when add-on systems are installed on either side of the double pane windows, the entire assembly acts as a triple pane IGU system with an additional air chamber created. Mass-air-mass-air-mass resonance may be found at low frequencies. Empirical measurements demonstrate the  limits  of  the  single  number ratings,  STC  and  OITC,  which may indicated  reduction in acoustic performance  when  there  is  a demonstrated  increase  in transmission loss at some 1/3 octave band frequencies. The information provides guidance in the selection of window add-on system for existing residential buildings that have high exposure to road traffic noise.





How to Cite

Mak J, Connelly M. Increasing Sound Insulation of Window with Add-on Systems & Various Insulating Glass Unit Configurations. Canadian Acoustics [Internet]. 2016 Aug. 24 [cited 2021 Oct. 28];44(3). Available from:



Proceedings of the Acoustics Week in Canada