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Double Glazing & Noise Reduction – Debunking the Myths

Double Glazing & Noise Reduction

Double Glazing & Noise Reduction – Debunking the Myths

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Whether you are at home or in the office, windows protect you from unwanted outdoor elements like noise or extreme temperature. That’s why it is important to choose the best solutions when treating your windows either for noise reduction or thermal insulation.

While you can find endless ideas online on how to manage those noisy neighbours, it can be challenging to find one that is effective and last for the long term.  Despite what you find, soundproofing is so much more than throwing a rug on the floor or placing more furniture in the noisier part of your home to absorb sound.

Soundproofing requires a professional’s expertise to achieve optimal noise reduction.

As specialists in acoustic (and thermal) insulation, these are some common myths relating to soundproofing and window glazing that you should be wary about.

MYTH #1: Wider gaps offer better soundproofing

“Huge air gaps when double glazing gets you better results”

While wider gaps help in noise reduction, after a point, the gap becomes a problem for thermal insulation, which is not ideal given Australia’s harsh climate. Wide gaps make room for more air circulation, while a narrow one restricts it.

To create better thermal insulation with excellent soundproofing, ensure your double-glazed windows have optimally sized gaps that are fit for purpose. It is recommended that the thickness of the insulation product be identical to the frame cavity depth.

MYTH #2: Double glazing is more expensive compared to secondary glazing

What may seem like a cost difference issue, is one of the biggest reasons property owners are misled when thinking of window solutions. Homeowners are always looking for affordable options to reduce noise while retaining the charm of their windows.

A secondary glazing can be less expensive than double glazed, yet offers more benefits. This means you can enjoy the benefits of double-glazed windows, without having to replace your existing ones, all at a fraction of the cost. Secondary double glazing is a long-term cost-saving option that addresses both acoustic & thermal concerns as well as the aesthetic requirement that a replacement window may not be able to achieve.

MYTH #3: Secondary glazing offers better noise reduction than double glazing

“Secondary glazed windows usually use slim glass, ensuring high noise reduction”

This is a myth. The fact is that any experienced window professional wouldn’t recommend a thin glazing solution with glass and tiny gaps. Double-glazed windows come with thick and durable shields that fully soundproof your space and are customisable to your property.

Most double-glazed window solutions will reduce noise levels by 50-70%. This means that you can install double glazing without sacrificing your lifestyle or connection with neighbours, while simultaneously enjoying better sleep and more efficient energy usage.

MYTH #4: Double glazing is a quick and easy DIY

“It’s glazing a window; how hard can it be?”

No matter how skilled you are at home improvement projects, double-glazing a window is no easy feat. Double-glazed windows usually require skill in working with materials like glass, acrylic and more to ensure the window is fitted and glazed correctly.

While this sounds simple in theory, if your measurements and cutting are incorrect or your DIY kit doesn’t come with the necessary tools, you’ll waste time and resources, only to achieve poor results. Double-glazed windows are built to reduce noise, so have it fit by a professional to experience the best results.

The Double Glaze Windows Advantage

Sound travels in pressure waves, and when it hits a single glazed window, the glass pane vibrates, carrying the sound. Opting for single-glaze windows also puts your home at risk of noise pollution and reduced thermal insulation. In a comfortable home, you want equal amounts of both.

A double-glazed window offers more sound insulation with two panes of glass with a spacer in between and sealed, trapping air inside, ensuring a range of benefits including improved sleep and productivity lower stress levels, and a comfortable living environment for you and your family.

Magnetite retrofit double-glazed windows and Soundtite secondary aluminium system are perfect solutions for maximising soundproofing. For older style timber windows or heritage properties, Magnetite is an ideal solution as it has minimal impact on the building’s façade.

Through a customised installation, homeowners can enjoy all the benefits of double glazing and an improved level of comfort in their homes. The system is fit on the inside of the windowsill, which means it is virtually invisible from the outside, making it the perfect upgrade to strata units, semi-detached or stand-alone homes as well as office environments.

Contact Magnetite team today to get a free quote for soundproofing your windows.

  1. Conduction
    Heat moving through an object (i.e. heat will travel through an aluminium, or steel frame more easily than through a timber or PVC frame).
  2. Radiant heat
    Heat from the direct sun. It can pass through space until reflected or absorbed.
  3. Convection
    Heat flow resulting from air movement e.g. either 'natural' convection - warm air rises, or 'forced' convection - a breeze by a window, both can result in a draught by a window.
  4. Infiltration
    Air leaks around the frame, around the window sash and through the gaps in the movable window parts.

When evaluating your options to improve the thermal performance of your windows, the following double glazing key performance criteria should be considered:

  • U-Value (Uw) represents heat transfer through a window, irrespective of direct sunlight. The lower a window’s U-Value, the better the insulation performance.
  • Solar Heat Gain Coefficient (SHGC) measures the solar energy that passes through glazing. The lower the SHGC, the less solar heat is transmitted through a window.
  • Air Infiltration or leakage measures the rate at which air passes through gaps in window joins and seals. The lower the air infiltration, the better a window’s energy performance.

The Window Energy Rating Scheme (WERS) Thermal Performance

Aluminium Frame Windows

Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC
Single glazed 3mm clear glass* half blue star red starhalf red star 7.4 0.77
Single glazed 3mm clear glass &
4.5mm Magnetite		 blue starblue starhalf blue star red starred starred starred starred starhalf red star 35% 59% 2.9 0.67

Timber Frame Windows

Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC
Single glazed 3mm clear glass* blue starhalf blue star red starred starred starhalf red star 20% 28% 5.5 0.69
Single glazed 3mm clear glass &
4.5mm Magnetite		 blue starblue starhalf blue star red starred starred starred starred starred star 37% 61% 2.6 0.66
Single glazed 3mm clear glass with
Solartite** and 4.5mm Magnetite		 blue starblue starblue starblue starblue starblue starhalf blue star red starred starred starred starhalf red star 76% 45% 1.8 0.20

 

*WERS standard typical industry window
**Solartite is a range of high performance window film. The window tested above has Solartite’s low-e film.

Magnetite vs Traditional Double Glazing – What the experts says

Winter - the ideal situation is to let in as much of the sun's heat and then trap it inside to maintain a comfortable environment in your home or office. This will also significantly reduce heating costs and saves you money. The ideal window for winter will have a high SHGC to let the sun's heat in and a low U-Value to prevent the heat from escaping. Clear windows without shading films are better suited for winter climates.

Compared with traditional double-glazing, Magnetite’s double-glazing solution can provide better results during winter or for cold climate areas such as Canberra, the Adelaide Hills and Blue Mountains.

Magnetite's clear acrylic window panels allow the direct heat from the sun's rays to enter the building and once inside, Magnetite's superior magnetic seals retain the heat, giving Magnetite an advantage over conventional operating windows.

Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC AI
Double Glazed 3mm clear glass/12mm air
gap/3mm clear glass IGU (Insulated Glass Unit)*		 blue starblue starhalf blue star red starred starred starred starred starhalf red star 40% 55% 3.0 0.61 5.0
Single glazed 3mm clear glass &
4.5mm Magnetite		 blue starblue starhalf blue star red starred starred starred starred starred star 37% 61% 2.6 0.66 0.5

 

*WERS standard typical industry window

Summer - the ideal situation is to minimize the heat coming in from outside and prevent the cool air inside from escaping through the window. This will make your home more comfortable and reduce your air-conditioning costs. The ideal window for summer, or for a large west-facing window, will have a low SHGC to limit the heat from the sun's direct rays, as well as, a low U-Value to prevent the heat in the air outside from moving through the window and warming the cool conditioned air inside. It is better to have a shading film on the first (outer) glass pane to limit the heat that enters the double glazed unit.

The combination of Magnetite retrofit double glazing and Solartite outperforms the traditional insulated glass unit for hot climate. Magnetite fit over an existing window with reflective film will give better summer heat control than a double-glazed window with supertoned glass.

The Magnetite system stops the conduction and convection of heat better than glass windows giving superior results for summer conditions. Combined with a film or a shading device, Magnetite is the ideal solution for the hot Australian conditions.

Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC AI
Double Glazed 5mm Supertoned glass/6mm
air gap/5mm clear glass IGU (Insulated Glass Unit)*		 blue starblue starblue starhalf blue star red starred starred starred starhalf red star 54% 425% 3.30 0.461 5.0
Single glazed 3mm glass Solartite**
and 4.5mm Magnetite		 blue starblue starblue starblue starblue starhalf blue star red starred starred starred star 73% 38% 2.4 0.19 0.5

 

*WERS standard typical industry window
**Solartite is a range of high performance window film. The window tested above has Solartite’s low-e film.

Click here to view pdf version of Magnetite WERS test result.

Noise Reduction Technical Data and Results

Proven Results

Noise pollution is one the biggest problems faced in the cities today, particularly in a high-density living. Unwanted noise can be responsible for sleep loss and lack of concentration. This can lead to a deterioration of health through increased stress levels, headaches, high blood pressure and loss of hearing.

Noise penetrates windows through leaky seals or vibrations through the window structure. To reduce noise, a window should minimise air infiltration, hold enough weight to limit vibration and allow a large air cavity. This cavity, or air gap, is the key to secondary glazing.

Expert Advice:

CSIRO Research by John Davy shown an air cavity can effectively enhance sound insulation performance. The larger the air cavity the more noise the window system can reduce. Results show a wide air gap of 100-125mm will improve sound insulation by an average of 7dB(A) more than windows with a narrow gap of 8-13mm.

Window or Glass Door Type Total Glass Thickness (mm) Air Cavity Thickness (mm) Sound Insulation (dB)
Single Glaze 3mm 3 0 23
Single Glaze 6mm 6 0 27
Double Glaze Narrow Gap 9-12 8-13 31
Double Glaze Wide Gap 9-12 100-125 38

 

The human ear is less sensitive to low frequency sound. According to a study released by the CSIRO, the human ear needs a change of 3dB to detect a difference in noise levels and the human ear perceives a change of 10dB as a doubling or halving of the noise level.

If you double the thickness of glass in a window the noise level will decrease by 3dB the least amount possible to make a difference. If the glass is laminated there is no perceived difference in noise reduction.

National Acoustic Laboratory Testing:

Working with the principles of noise transfer, Magnetite® and Soundtite are designed for high performance, which is achieved by combining air tight seals with the ability to maximize an air cavity and the flexibility to vary glazing thickness to suit. Magnetite® is excellent at reducing general noise such as busy roads, commuter trains and noisy neighbours. Whereas, Soundtite works well to combat low frequencies noise such as garbage truck, freight trains or airplane during take-off and landing.

Test Code Material Tested Rw* Improvement
ATF 707 (test window) Aluminium sliding window, 3mm float glass with mohair seals 23 N/A
ATF 709 Test window, 100mm air gap and Magnetite System (4.5mm acrylic panel) 35 52%
ATF 1507 Test window, 100mm air gap and Magnetite System (10.0mm acrylic panel) 39 70%
ATF 817 Test window, 100mm air gap and Soundtite (6.38mm laminated glass) 41 78%

 

*The Weighted Sound Reduction Index (Rw) is a measure for sound insulation performance of a single building element such as windows. The higher the Rw rating, the better the sound insulation.