Why Single Glazing is Failing Australian Homes

If you're a home builder or homeowner in Australia, chances are you're dealing with single glazed windows that are letting air in and out too easily. Unfortunately, they're probably costing you more than you think. As window specialists, we see the same problems: sky-high energy bills, uncomfortable homes, and frustrated families trying to stay warm in winter and cool in summer. But it doesn’t have to be this way. 

Let's break down why single glazing just doesn't cut it in the Australian climate, and what you can do to fix it.

What is single glazing? 

Single glazing is a window made with just one pane of glass separating the inside of your home from the outdoors. Many old Australian homes, especially those that haven’t been renovated in recent years, still have single glazed windows since they were once the standard. Unfortunately, this type of glazing often comes with a few issues.

What problems do single glazed windows cause? 

Single glazed windows are both thermal weak points and limited insulators. They allow for up to 87% more heat to pour in during summer and let 40% of your precious heated air to escape during winter. This is because single panes of glass are only 3mm to 10mm thick and offer virtually no barrier against temperature transfer. They can develop drafts through worn seals or small cracks, making your heating and cooling system work harder. 

Then, when too many drafts start happening, it can create hot or cold spots around the windows causing issues towards maintaining consistent temperatures indoors. When seals and cracks aren’t fixed, it makes it easier for outsiders to break in, as you have gaps they can use to their advantage. Plus, the thin 3mm-10mm glass pane isn’t going to protect much either. 

When you consider that 40% of your household energy consumption goes into heating and cooling, it can be painful to learn that your single glazed windows may be the ones causing your power bills to keep climbing and home safety to be at risk.

How are these windows failing Australia?

Say you live in a century-old art deco apartment in Melbourne. Since windows are most likely original, tenants will probably find themselves shivering through chilly Melbourne winters and paying increasingly high power bills to warm the apartment with electric heaters. This is because Australia consistently ranks behind other developed nations when it comes to energy efficiency standards.

While countries like Germany and Scandinavia mandate high-performance windows, we're still predominantly installing single glazing in new builds. This gap is hitting Australian families directly in their wallets through higher energy costs and reduced comfort.

An example of triple glazing, one of the best-performing window options.

3 ways to improve single-glazed windows

As a nation, we don't have to stick with single-glazed windows. There are multiple upgrade options available for a variety of prices to improve indoor living conditions and energy bills.

1. Low-emissivity (low-e) glass

Investing in new glass can make all the difference to your windows. If you're on a budget, brand new windows might seem too expensive. Yet rather than leaving your single-glazed windows as they are and dealing with the problems that come with them, consider upgrading to more energy-efficient glass like low emissivity.

Low emissivity (low-e) glass is an energy-efficient option designed with a microscopically thin metallic coating. This coating is transparent to the eye, but helps reflect infrared heat and ultraviolet (UV) light away from the window. It was created specifically to reduce the transport of heat or cold through the glass. 

Low-e glass comes in two types. The first type is high-transmission low-e glass, which has a special coating that lets sunlight into the house for warmth but stops heat from escaping back out through the window. Low-transmission low-e glass has a coating that blocks some of the sun's heat from getting in while still letting plenty of light through. Both types of low-e coatings on windows help control heat flow where you need it.

If you're considering low-e glass, the process is quite straightforward. A glazier will measure your existing window frames, remove the old single-glazed glass, and install new low-e glass that fits perfectly into the same frames to get the energy efficiency benefits. It's a permanent upgrade that costs much less than replacing the entire windows, making it a smart choice when you want better performance on a budget. However, you should be wary that single glazed low-e is mixed into the glass and can result in cloudy-looking, tinted glass.

2. Secondary glazing

Secondary glazing offers another practical solution without the expense of replacing entire windows. With this option, you install a glazed panel in a frame over your existing window, creating an extra layer of insulation. It's particularly brilliant for Melbourne apartment dwellers since it typically doesn't require owner corporation approval because you're not actually changing the original window structure.

It’s important to be careful with original hardware, as doubling of glass weight can cause operational issues. We recommend upgrading seals and draft stopping at the same time.

3. Double or triple glazed windows

When it comes to managing interior heat and cool levels, nothing beats the superior thermal performance that double or triple glazed windows deliver year-round. They're not only the gold standard in home comfort but also a smart long-term investment through lower energy bills. These high-performance windows have been standard in Europe for decades due to harsh winters, and Australians are now recognising their value for our extreme climates of scorching summers to chilly winter nights.

Double or triple glazing (also called IGUs) combines two or more layers of glass sealed into a frame with gaps between each layer. These multiple layers create sealed cavities that drastically improve energy performance compared to single glazing because they transmit far less energy.

The energy performance of double glazing vs single glazing windows depends on three key factors. Double and triple glazing is based off:

1. The properties of the glass itself: Whether it's clear, tinted, or low-e glass, each window delivers different solar heat gain and light transmission values. 

2. What's inside the cavity and how big it is: These gaps can be filled with air or inert gases like argon for better insulation, with cavity widths typically ranging from 6 to 18mm. Wider cavities generally provide better insulation, with 12mm being the sweet spot. The cavity must stay dry and well-sealed to prevent moisture getting in. 

3. The spacer: There’s a metal or polymer strip, known as the spacer, that separates the glass layers and contains a desiccant to absorb any moisture, it’s important you have a good one to avoid condensation build up.

If you’re building or renovating a home, investing in these thicker glazed windows will make a massive difference for your overall comfort and long-term financial health.

What’s the price difference between the 3 options

Low-e retrofit glass is typically your most affordable option from $185 per square metre, where a glazier simply removes your old single-pane glass and replaces it with new low-e glass in your existing frames, making it quick and straightforward.

Secondary glazing sits in the middle price range at around $500-$1000 per square metre, and you've got the choice of DIY installation with some companies providing step-by-step guides or professional fitting, which is recommended for the best results. 

Finally, full double or triple glazing replacement is the most expensive option, potentially costing anywhere from $1000 to $1,500 per square metre depending on specifications, though the extra investment pays itself off over time in greater energy efficiency.

If you're budget-conscious, low-e retrofit gives you energy efficiency gains with minimal fuss, while secondary glazing offers a middle-ground solution that's particularly good for renters or apartments where you can't replace the original windows. Double or triple glazing is ideal for home builders or renovators planning to stay in the property long-term and want maximum performance.

Invest in high-performance windows to improve your home

When you upgrade from single glazed windows to high-performance alternatives, you'll enjoy greater thermal comfort, better control over ventilation and natural light, plus significantly reduced noise from outside. While the cost is bigger upfront, it’s a long-term investment that will truly make a difference. 

At Miglas, we specialise in helping Australian homeowners choose the perfect glazing solutions for their needs and budget to have the perfect insulated house. Our expert team can guide you through the options and deliver professional installation here in Melbourne.

Contact us today for a consultation and discover how the right windows can make all the difference to your house installation.