Acoustic glazing: how 45 dB is actually achieved
The 45 dB figure is a system property, not a glass property. AC-90 pairs a 47 dB asymmetric laminated IGU (24–42 mm total) with a sealed dual-cavity frame and a dedicated acoustic gasket, certified to Rw 45 dB to EN ISO 10140-2. The frame has to be as quiet as the glass — air leaking past the sash bypasses the glazing entirely, which is why Class 4 airtightness is part of the acoustic build rather than a separate specification line.
Why the glass alone cannot deliver the number
Sound takes the path of least resistance. A 47 dB pane in a frame that leaks at the meeting stile or the sill performs at the leak, not at the pane — the measured performance of the whole unit is set by its weakest member, and on windows the weakest member is usually a joint. The AC-90 build attacks the problem in three places: the glazing (asymmetric laminated core), the frame (a sealed dual cavity, so the sound cannot tunnel through the profile), and the gasket line (a dedicated acoustic compression, not the weather seal doing double duty).
The glazing, asymmetric on purpose
Asymmetry is the working principle: two panes of the same thickness in coincidence amplify the sound at a narrow band, so the build pairs different masses with an interlayer — a laminated unit from 24 to 42 mm total where the panes do not mirror each other. The mass selection follows the noise survey, not the style: arterial traffic is mid-band, an airport radius is dominated by the low-band rumble, and a rail frontage is the hardest case, because the low frequency wants more mass and a sealed cavity to keep it out. The survey sets the total mass and the interlayer, and the certification is run on that configuration.
What 45 dB means at the window
The field case on the schedule is the arterial road: a street measuring around 70 dB at the façade lands under 25 dB at the sash once the AC-90 unit is in place — the difference is the 45 dB the certification names. That is the number that lets the bedroom sit on the road and the meeting room sit on the rail line. The build runs as tilt-turn, casement, fixed, or the fixed corner unit, so the acoustic line follows the opening the drawing already has instead of the other way round.
Where the rest of the range picks it up
- PF-35 ACOUSTIC: the panoramic fixed line carries the 47 dB laminated IGU for the view-first elevation that cannot give up the glass.
- WA-70 ACOUSTIC: wood-aluminium — timber mass inside, bonded aluminium outside — the certified 45 dB build for the design-led street frontage.
- SM-60 smart operation: the drive closes the acoustic sash on the rain sensor and the schedule, which is how the 45 dB stays in the room instead of being voided by an open window at 6 pm.
Questions
It is the laboratory rating of the unit. The field result is set by the survey and the installation — the Class 4 airtightness of the build is what keeps the field close to the lab.