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Is double glazing worth it in Canberra? How windows affect heat loss and heat gain.

Is double glazing worth it in Canberra? How windows affect heat loss and heat gain.

Posted on in Blog

In Canberra, windows are one of the main places a home loses warmth in winter and takes on heat in summer. Retrofit double glazing improves how existing windows perform in both seasons, without replacing them.

Canberra’s climate asks a lot of a home. Frosty mornings through winter give way to hot, dry summer afternoons, and the temperature can shift a long way between day and night. Many homeowners have already topped up ceiling insulation or sealed obvious gaps, yet still find some rooms hard to keep comfortable. More often than not, the windows are part of the story.

Why does my house still feel cold when the ceiling is insulated?

Insulation in ceilings and walls slows heat moving through the solid parts of your home. A single pane of glass does far less to slow that movement. In winter, warmth from your heater moves out through the glass, and you feel it as a cold zone near the window. In summer, the reverse happens, with heat moving in and building up through the afternoon.

That is why a home can be well insulated overhead and still feel uneven. Windows are rarely the only factor, but in many Canberra homes they are one of the largest that hasn’t yet been addressed.

When is the best time to install double glazing in Canberra?

With winter behind us, it is easy to put window comfort off until next year. Spring is actually a practical time to act. Summer heat gain is only weeks away, and installing before then means you feel the benefit in both the hottest and coldest parts of the coming year.

How does retrofit double glazing work?

The Magnetite system adds a second layer of glazing to the inside of your existing window. It installs onto the window sill or reveal, and your existing window stays in place and unaltered. The sealed air gap between your existing window and the new secondary window slows heat moving in either direction, which helps rooms hold a steadier temperature.

Because there is no window replacement, installation is cleaner and quicker than a full change-over, and it will not change the look of your home from the outside. It is a cost effective way to improve comfort in homes where replacing every window isn’t practical.

Which windows should I double glaze first?

  • Living areas where you run the heater or air conditioner most
  • West-facing rooms that heat up through summer afternoons
  • Bedrooms that feel cold on winter mornings
  • Large windows and sliding doors, where more glass means more heat movement

A Magnetite representative can assess your home and recommend which windows will make the most difference.

Frequently asked questions

Does double glazing help in summer as well as winter? Yes. The same air gap that slows warmth escaping in winter also slows heat coming in during summer, helping rooms stay more comfortable in both seasons.

I already have ceiling insulation. Will windows still make a difference? Often, yes. Ceiling insulation and windows deal with different parts of your home. If rooms still feel cold near the glass or overheat in the afternoon, the windows are worth looking at.

Do I need to replace my windows? No. Magnetite fits into your existing window sill or reveal, leaving the optimum air gap for the best acoustic and thermal insulation.

Will it help with condensation? It can reduce condensation on the inside of the glass in colder months, as the Magnetite panel stays warmer than a single glazed window.

Call to action: Book a free measure and quote with your local Magnetite Canberra team to find out which windows will make the biggest difference.

Related reading: 5 Ways To Stay Warm This Winter In Canberra, How To Thermally Insulate Windows: A Complete Guide and How to Reduce Noise at Home in Canberra. 

  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.