Argon, Krypton, or Air: Gas Fills for Double Glazing in Australia

Many homeowners only hear about gas-filled double glazing in Australia once they start comparing double glazing quotes. One supplier might promote argon, another may mention krypton, and a third may simply list “sealed air cavity” without much explanation.

On paper, these choices look technical. In practice, they affect the thermal performance of your windows, how they feel on a hot afternoon, how quickly rooms lose warmth overnight, and how easily you can maintain comfort without over-relying on heating and cooling.

At APS Double Glazing, we find that once people understand what argon gas, krypton gas, and even plain air actually do inside insulated glass units (IGUs), it becomes much easier to make a choice that feels sensible rather than purely theoretical.

This guide explains how gas fill options work in double glazed windows in Australia, how each behaves in local conditions, and where the real-world differences are most likely to appear in your home.

What the Gas Between the Panes Actually Does

Every double glazed window unit contains a sealed space between the panes, forming the cavity used in gas-filled IGUs. That space can be filled with:

• ordinary dry air
• argon gas
• krypton gas
• or, in some high-performance systems, a blend

The basic job of the gas fill is to slow heat transfer through the window. It does this in three main ways:

• Reducing convection inside the cavity
• Changing how well the gas conducts heat
• Working with low-E coatings and spacers to control radiant heat paths

Even with a clear view through the glass, the gas cavity is not empty. It is carefully sized and sealed so the gas inside behaves in a predictable way as outdoor and indoor conditions change.

Snapshot: Air vs Argon vs Krypton

Before going deeper, it helps to see how the three common options compare in simple terms.

Gas fill	Typical use in Australia	Relative cost	Typical benefit vs plain air*
Air	Budget or basic double glazing	Lowest	Baseline performance
Argon	Most modern energy-efficient IGUs	Moderate	Typically improves insulation performance in many homes
Krypton	Specialised, narrow or high-performance units	Highest	Further improvement, mainly where the cavity is very narrow, or performance targets are strict

*Benefits depend on glass type, cavity width, frame, coatings and climate.

Rather than asking which double glazing gas fill is “best”, it is usually more helpful to compare argon vs krypton vs air and ask which option fits your window design, climate and budget.

How Gas Fills Change Window Performance

Each gas affects heat flow in its own way, so the choice of fill directly shapes how well a window insulates across Australia’s shifting conditions.

Air as the baseline

Dry air is the default reference point. It is inexpensive and easy to seal, but it allows more heat transfer than argon or krypton. With air-filled double glazing, you still gain a large step up from single glazing, because you now have:

• a second pane
• a sealed cavity that slows heat flow
• potential for low-E coatings and better frames

However, air tends to be more mobile inside the cavity, so small convection currents form and transport heat across the gap more quickly than in heavier gases.

Argon, the practical workhorse

Argon is one of the most common upgrades in modern IGUs in Australia. It is:

• Heavier than air, which reduces internal air movement
• Less conductive than air, so it resists heat transfer more effectively
• Colourless and odourless, so it does not change the view or the glass appearance

In many standard double glazed units with cavity widths around 12mm to 16mm, argon often provides a good balance between performance gain and cost.

Homeowners may notice:

• rooms holding warmth a little longer on cold nights
• glass surfaces feel less “cold” to the touch in winter
• a calmer, more stable indoor temperature during changeable weather

Krypton, the specialist option

Krypton is denser again and conducts heat even less than argon. It is usually used when:

• the cavity between panes is narrower than usual, for example, 8mm to 10mm
• very high performance is needed, such as in some Passive House or advanced thermal designs
• triple glazing or complex glass combinations are specified, and every small gain matters

Because krypton is more expensive, it tends to appear in projects where achieving a particular thermal rating is essential, or where window design limits cavity width, and argon cannot perform at its best.

For many standard Australian homes with typical cavity sizes, the extra benefit of krypton over argon may be modest compared with the additional cost.

Gas Fills Through an Australian Climate Lens

Australia covers a wide range of climate zones, from hot and humid to cool and alpine, so choosing double glazing for the Australian climate needs to consider local conditions. The way air, argon and krypton behave needs to be seen in that context.

Hot and humid regions

In tropical and sub-tropical areas, key concerns include:

• managing solar heat gain
• reducing indoor heat build-up in the afternoons
• managing condensation on the inside and outside surfaces

In these regions, argon-filled units combined with appropriate solar control or low-E glass may:

• help slow the heat entering the home
• reduce the risk of the inner pane feeling uncomfortably warm
• support air conditioning systems by lowering peak heat loads

Krypton may offer further improvement, although in many typical homes, careful glass selection and shading design often provide more practical benefits than upgrading from argon to krypton.

Temperate coastal cities

In cities such as Melbourne, Sydney, Adelaide and Perth, many homes with large sliding windows and glass doors can experience both winter cold and summer heat. Here, argon-filled double glazing can support:

• better winter comfort in living rooms and bedrooms
• reduced reliance on artificial heating and cooling
• more stable temperatures during windy, changeable days

In this context, argon is often a practical “sweet spot” when paired with suitable low-E coatings, cavity width and well-insulated frames.

Cooler southern and inland regions

In alpine or cooler inland areas, keeping heat inside at night is critical. Higher-performing IGUs, sometimes including triple glazing or krypton, may be considered in:

• homes built to very high efficiency or Passive House standards
• properties where winter temperatures are consistently low
• projects aiming for specific high NatHERS or similar energy ratings

For many standard window replacement projects using double glazed units in these regions, argon-filled IGUs with good frames may deliver a strong uplift in comfort without the complexity of krypton.

When Plain Air May Still Be Reasonable

There are situations where a well-made air-filled IGU can still be a practical budget double glazing choice, for example:

• Small windows in secondary spaces, such as laundries or storerooms
• Tight renovation budgets, where upgrading from single glazing to basic double glazing is already a significant step
• Shaded openings that do not experience strong temperature swings

In these cases, the main gain comes from the second pane and the sealed cavity itself. While argon could still improve performance, the marginal benefit might not justify the additional cost for every window.

When Argon Fill Usually Makes Sense

Argon-filled IGUs often suit homeowners who want better year-round comfort in double glazing for living areas without moving into highly specialised glazing.

Some examples include:

• Main living areas with large sliding & patio doors or windows
• Bedrooms where stable night-time temperatures support sleep
• Renovations where energy ratings are a consideration, and homeowners are exploring the benefits of double glazing for energy efficiency
• Open-plan layouts where one zone can influence comfort in the whole space

In these situations, argon:

• can improve thermal performance compared with air
• works well with typical Australian cavity widths
• is widely available from reputable IGU manufacturers

For many homes, argon-filled double glazing forms part of a “sensible middle path” upgrade, where the goal is better comfort and reduced energy use rather than chasing extreme performance levels.

Where Krypton Fits, and Where It May Not

Krypton double glazing tends to be considered when the design or performance brief demands more than argon can realistically provide, and high-performance IGUs are needed.

It may be worth exploring when:

• window or door designs require very narrow cavities
• specific high-performance standards are being targeted
• a project already includes triple glazing or other advanced measures

However, krypton may be less suitable where:

• budgets are tight, and other upgrades would deliver better value
• frames or installation quality are average, which can undermine the gains from a premium gas fill
• the local climate does not fully take advantage of the extra performance

In short, krypton can be useful in the right context, but it is rarely necessary for everyday renovations or typical suburban homes.

The Gas Fill Is Only One Part of the Story

It is easy to focus on the gas because it is a simple line item in a quote. In reality, overall window performance depends on how multiple elements work together.

Factors that matter as much as the gas include:

• Glass type and coatings – clear, tinted, low-E and laminated combinations
• Cavity width – argon and krypton have “sweet spots” for different gap sizes
• Spacer design – warm edge spacers help reduce edge-of-glass heat transfer
• Frame material and construction – uPVC, thermally improved aluminium, and some composite frames can support the IGU’s performance
• Installation quality – poor sealing around the frame can allow unwanted air leakage, undermining even the best IGUs

A well-designed window system treats the gas fill as one component among many, not as the only feature that matters.

Common Questions About Gas Fills in Australian IGUs

Many people have similar concerns about gas-filled units, and answering them helps clarify what matters in everyday use.

Will the gas leak out quickly?

High-quality IGUs used in gas-filled double glazing are designed so that any gas loss is gradual over many years, supporting the overall lifespan of IGUs. Small reductions in argon content do not cause an immediate failure, and the unit can still perform better than a basic air-filled cavity for a significant part of its life.

Over time, if seals deteriorate or moisture enters, fogging or misting may appear between the panes. This is usually a sign that the entire IGU needs replacement, not just a “top-up” of gas.

Is argon or krypton safe?

Argon and krypton are inert gases. They do not burn, and they do not react with other materials inside the IGU. If a pane breaks, the gas dissipates harmlessly into the surrounding air.

Can I tell what gas is in my windows just by looking?

No. Argon and krypton are invisible. In most cases, the most reliable way to know is through documentation from the manufacturer or installer. Some high-quality suppliers etch or label their units with key details, but this is not universal.

How to Decide What Is Right for Your Home

When thinking about argon, krypton or air for your Australian home, it may help to work through questions such as those considered when choosing the right double glazed windows and doors:

• What are my main comfort issues, for example, summer heat, winter cold, or both?
• How large are the glazed areas, and which rooms matter most?
• Am I aiming for a moderate performance uplift, or targeting very high efficiency?
• How does my budget look when I consider other improvements, such as shading, insulation or more efficient heating and cooling?

In many projects, homeowners find that:

• Air-filled IGUs can be suitable for smaller, less critical openings
• Argon-filled IGUs suit most main living and sleeping areas where comfort is a priority
• Krypton-filled IGUs are reserved for specialist situations, narrow cavities or high-performance builds

A balanced approach often uses different glazing types and gas fills throughout the home, rather than applying a single solution everywhere.

Designing Windows That Feel Right to Live With

Modern glazing is not just about ticking boxes on a specification sheet. It is about creating windows and doors that feel comfortable to live alongside every day.

Used well, argon, krypton or even plain air inside a thoughtfully designed IGU can:

• soften temperature swings
• support quieter, calmer interiors
• help your home use energy more thoughtfully

The most suitable choice is the one that fits your climate, your home’s design and your long-term plans.

If you are comparing double glazing options or wondering whether argon or krypton is worth it for your situation, you can get in touch with APS Double Glazing. We can walk through likely performance differences, typical installation timeframes, and what combinations may suit your home and budget.

Disclaimer: This guide provides general information only. Window and door performance, lifespan and installation requirements can vary by product, home design and climate. It is always best to seek advice based on your specific property and circumstances.