Quieter and warmer windows: acoustic laminated glass vs double glazing

Two complaints bring most Melburnians to new glass: "I can hear every truck" and "the house is freezing in July". The fixes overlap, but they aren't the same. Laminated glass is the noise specialist. Double glazing is the heat specialist. Here's how they compare, what the ratings mean, and when it's worth combining them.

Two numbers worth knowing

For noise: Rw and Rw+Ctr. Both measure how much sound a window blocks, in decibels; higher is better. Rw+Ctr adjusts for low-pitched sound, the rumble of traffic, trams, trains and aircraft, so it's usually the fairer number for a Melbourne home near a road (AGWA). As a rule of thumb, cutting noise by about 10 dB makes it sound roughly half as loud.

For heat: the U-value. It measures how fast heat passes through the whole window; lower is better. Windows matter a lot: up to 40% of a home's heating energy can be lost through them, and up to 87% of its summer heat gained (YourHome).

Noise: how the glass compares

Typical published figures for the glass alone (the frame and seals bring the real window down a little):

What stands out:

• A single acoustic laminated pane can match or beat standard double glazing for traffic noise. Ordinary double glazing with two equal panes and a narrow gap isn't built for noise; glass makers say it does little extra for sound (Viridian).
• Different panes beat matching ones. Two panes of different thickness don't vibrate at the same pitch, so a double-glazed unit with, say, a laminated pane on one side does better than two identical panes.
• The frame and seals often set the limit. Gaps around a sash let sound straight through. Sliding windows and doors seal less tightly than awning or fixed windows, so on a noisy street the window type matters as well as the glass.

Heat: double glazing does the heavy lifting

Laminated glass on its own keeps heat in about as poorly as ordinary glass. For warmth, you need double glazing, a Low-E coating that reflects heat back into the room, or both.

• Single-glazed aluminium windows typically have a whole-window U-value around 6 to 7.
• Double-glazed aluminium windows sit around 3 to 4.5.
• Thermally broken frames with Low-E glass can get down towards 2.

Sustainability Victoria says double glazing cuts heat loss and gain by almost 30% compared with single glazing (Sustainability Victoria). In Melbourne, where homes need more heating than cooling, that's felt mostly in winter, as fewer cold spots near windows and less condensation on the glass.

The best of both

You don't have to choose. A double-glazed unit can have an acoustic laminated pane on one side and a Low-E pane on the other: quieter, warmer and safer in one unit. Laminated glass also holds together if broken, which helps with security too; see our guide to secure windows and doors.

Which to choose:

Keep your frames or replace them?

If your aluminium frames are sound, retrofit double glazing fits new double-glazed units into the existing frames, typically $600 to $1,800 per opening. If the frames are tired or you want a different style, a new double-glazed window is typically $2,300 to $3,500 installed. Our double glazing cost guide explains what moves the price.

Victoria's Energy Upgrades program offers discounts on some window upgrades through accredited providers, so it's worth asking about before you start.

Get a quote for quieter, warmer windows

We supply and fit acoustic laminated glass, double-glazed units with Low-E glass, and new aluminium windows and doors across our Melbourne service areas. Tell us what bothers you most, noise, cold or both, and we'll quote the glass that solves it, in writing, before any work starts. See sliding doors and double glazing or ask for a double glazing quote.