Double glazing can be worse than single glazing when panes match

Evidence

As an amusing example, Figure 6.56 shows the measured results, from Inman (1994), for singleand double-glazing made with similar and different thicknesses of glass and spacing. Because of the effect of the coincidence resonances, the double-glazed unit with 4 mm glass is actually worse than a single pane of 4 mm glass! As the other two curves show, if the glass is dissimilar, the result is much improved and is further improved if the spacing is increased so as to reduce the coupling — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2120

Categorization

Category: Contrarian or Surprising Claims

• SHARE: Worth sending to anyone who does window or acoustics work — a matched double-glazed pane outperformed by a single pane is a memorable engineering gotcha.
• SEED: Angle: ‘why your double glazing might be worse than a single pane’ — coincidence resonances are a concrete case where more material nets less performance.