Acoustic comfort in office buildings with double skin glass façades

In the Project TwinSkin at the IGS Institut für Gebäude- und Solartechnik (Institute for Building Services and Energy Design) Brunswick/Germany, nine office buildings with double skin glass façades (DSF) were i.a. acoustically evaluated. Double skin façades (DSF), in comparison with other kind of façades, are frequently promoted to provide higher sound insulation from external noise, especially road traffic noise. DSF offer the advantage of operable windows or doors to the cavity, which provide occupant comfort; however, than questions about the impairment of acoustic comfort arise. The objective was to thoroughly analyse the apparent sound insulation properties of DSF in the extended frequency range from 50 to 5000 Hz. Measurements were performed according to the standard EN ISO 140-5 for different operation conditions of the openings and single number quantities were calculated. Additionally their respective spectrum adaptation terms (C and Ctr) were considered. A remarkable influence of DSF design on the sound insulation properties was found. The results show high levels of weighted apparent sound reduction up to 60 dB, but also there were results from only 35 dB to 40 dB. Multi storey façades tend to better sound insulation performance in relation to the other types of DSF, an average of 13 dB higher values were found. Esthetical favourable arrangements of DSF can provide substantial negative influence on sound insulation.