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Taking on a home project often involves many decisions. This is true whether you’re renovating or building new. One area that usually requires careful thought is the choice of windows and doors, particularly the type of glazing used.
The priorities for someone updating a 1960s weatherboard cottage may differ from those designing a contemporary new home. Factors such as heritage overlays, energy efficiency standards, and local climate conditions can influence the path you take.
APS Double Glazing is an Australian provider of double glazed windows and doors, with experience working across both renovation and new build projects. The team understands that no two homes are the same, and the right glazing solution for one property might not be the best fit for another. In this guide, we explore the priorities that may arise in renovations and new home builds.
When you’re building a new home in Australia, energy efficiency requirements are built into the process from the very beginning. Under the National Construction Code (NCC 2022), most new homes must meet a minimum 7-star NatHERS energy rating. This represents an increase from the previous 6-star minimum. Glazing performance can play a meaningful role in reaching this benchmark.
For new builds, glazing decisions can usually be made early in the design phase — before walls go up and orientations are fixed. This allows builders and designers to plan windows around several factors, including:
In cooler climates such as Melbourne, north-facing windows with higher solar heat gain coefficient (SHGC) values may help warm the home in winter. Well-shaded east and west-facing windows may help limit unwanted summer heat.
Double glazing is frequently specified in new builds to help meet these thermal performance targets. When combined with appropriate frame materials – such as uPVC, thermally broken aluminium, or timber – double glazed windows and doors can contribute to a lower U-value for the overall building envelope, which may help reduce reliance on mechanical heating and cooling.
Another benefit for new home builders is the ability to integrate a Whole-of-Home energy budget. Introduced alongside the 7-star requirement, this considers not just the building shell but also the energy used by fixed appliances like heating, cooling, hot water systems, and lighting. Choosing high-performance glazing from the outset can potentially free up flexibility elsewhere in your design, which might allow for larger window openings or different material choices without compromising overall compliance.
Renovating an existing home brings a different set of considerations. Unlike a new build, you’re working within the constraints of an existing structure – which might include specific wall thicknesses, older frame types, heritage overlays, or body corporate requirements. The glazing priorities for a renovation often centre around improving comfort and addressing specific pain points, such as draughts, noise from nearby roads, or rooms that feel uncomfortably hot or cold at certain times of year.
One of the first decisions homeowners face when renovating is whether to choose:
Full frame replacement involves removing the existing window frames entirely and installing new double glazed windows with modern frames. This approach may offer the best thermal performance, as it allows for properly sealed, purpose-built units with the correct cavity width and gas fill. However, it can be more involved in terms of installation, particularly in older homes where wall cavities or reveals may not be standard sizes.
Retrofit or secondary glazing is another option, where a second layer of glass or acrylic is added to an existing single-glazed window. This can be a more affordable entry point and may suit homes with heritage considerations where the original window appearance needs to be preserved. While secondary glazing may not match the thermal performance of a manufactured insulated glass unit (IGU), it can still offer noticeable improvements in comfort and noise reduction, depending on the product and installation quality. Understanding the differences between retrofit and full replacement can help you weigh up what may work best for your situation.
It’s also worth noting that if your renovation is substantial – for example, affecting more than 50 per cent of the volume of the existing building – you may be required to meet current energy efficiency standards under the NCC. A registered building surveyor can help you understand what level of compliance applies to your specific project, as the requirements can vary depending on the scope of work and your state or territory.
Whether you’re renovating or building new, the climate you live in can influence which glazing characteristics matter most. In Melbourne and other temperate parts of southern Australia, the U-value of your glazing – which measures how well a window resists heat flow – is often an important consideration.
A lower U-value generally indicates stronger insulation. This may help keep warmth inside during winter and could reduce the load on your heating system.
For new builds, orientation can often be optimised from the outset. Designers may recommend maximising north-facing glazing to capture passive solar warmth during cooler months. At the same time, east and west-facing glass is often limited or carefully shaded to reduce unwanted summer heat.
For renovation projects, orientation is usually fixed. In these situations, selecting the right glass type for each window can still make a meaningful difference. For example:
The gap between the panes in a double glazed unit is another factor to consider. A cavity of at least 12mm, ideally filled with argon gas, is often regarded as a solid baseline for thermal performance in many Australian conditions.
Where noise reduction is a priority, a wider cavity – typically between 50mm and 100mm – may be more effective. However, this can sometimes slightly reduce thermal efficiency.
A qualified installer can help assess your home and recommend a glazing configuration that balances insulation, solar gain, and acoustic performance.
The frame material you choose can have a notable impact on the overall thermal performance of your windows. For new builds, the full range of frame options is typically available from the start, making it easier to select frames that complement the home’s design and energy goals.
uPVC frames are generally recognised for their strong thermal performance, durability, and low maintenance requirements. They can be moulded into complex profiles that can help provide effective air seals, and they don’t conduct heat the way aluminium does.
Thermally broken aluminium frames are another high-performing option, using a structural insulator between the inner and outer sections to reduce heat transfer.
Timber frames offer natural insulating properties and suit certain architectural styles, though they typically require more ongoing maintenance.
In some cases, composite frames – which combine aluminium on the exterior with timber or uPVC on the interior – can offer a practical compromise between performance and appearance.
For those renovating, the choice of frame material may be influenced by the existing structure. If you’re considering window replacement in Melbourne, you’ll need to consider the size and condition of the existing openings, as well as any aesthetic or heritage requirements.
For new home builders, meeting the 7-star NatHERS requirement is a mandatory part of the process. The good news is that when energy-efficient design is considered early, achieving this standard can often be possible without significant additional cost.
Many builders are already delivering homes at or above the 7-star level. Over time, improved energy performance may also contribute to lower energy bills.
Homeowners undertaking renovations may also benefit from available incentive programs.
In Victoria, the Victorian Energy Upgrades (VEU) program offers discounts for households upgrading from single-glazed to double glazed windows, provided an approved product is installed by an accredited provider.
Discount amounts can vary depending on factors such as:
Even so, the program may help reduce the upfront investment required for window upgrades. The VEU program has been extended through to 2045, giving homeowners some long-term confidence that support for energy efficiency upgrades is likely to remain available.
If your property has a heritage overlay, it’s worth checking with your local council early in the planning process. Some councils require approval for window changes that affect a building’s external appearance. There may also be requirements around maintaining the original character of the property.
In these situations, secondary glazing is sometimes a preferred option. It can preserve the appearance of the existing windows while still improving thermal and acoustic performance.
Regardless of whether you’re renovating or building new, it’s generally a good idea to consult a qualified energy assessor or building professional. They may be able to model different glazing scenarios for your specific home.
Understanding how double glazed windows are installed can also help you plan ahead. Tools such as the Window Energy Rating Scheme (WERS) allow homeowners to compare the heating and cooling performance of different window products. This can make it easier to evaluate glazing options before making a decision.
APS Double Glazing works with homeowners across both renovation and new build projects, manufacturing and installing double glazed windows and doors tailored to Australian conditions. The team’s experience across a range of home types means they’re familiar with the different challenges each scenario can present.
For renovation projects, APS can assess existing window openings and recommend solutions that balance performance, aesthetics, and budget. For new builds, the team can work alongside builders and designers to help specify glazing that supports compliance with the NatHERS 7-star standard, while also addressing comfort, noise, and security considerations.
With a focus on uPVC frames and high-quality insulated glass units, APS Double Glazing aims to provide products that may offer improved thermal stability, reduced external noise, and lower maintenance requirements over time – though outcomes will always depend on the individual property, installation quality, and local conditions.
The priorities around double glazing can look quite different depending on whether you’re starting with a blank canvas or working within the bones of an existing home. New builds offer the advantage of integrating glazing into the design from day one, with clear compliance pathways and the ability to optimise orientation and window placement. Those renovating, meanwhile, may need to navigate structural constraints, heritage considerations, and a wider range of glazing options – but can still achieve meaningful improvements in comfort, energy efficiency, and noise reduction.
In either case, taking the time to understand your home’s specific needs, your local climate, and the products available could help you make a decision that serves you well for years to come.
If you’re exploring options for double glazing – whether as part of a renovation or a new build – you’re welcome to contact the team at APS Double Glazing for guidance tailored to your situation.
Disclaimer: This article is for general information only. Building codes, energy efficiency standards, and government incentive programs may change over time, so it’s important to check the latest requirements with the relevant authority or a qualified professional before making decisions. Window and door performance may vary depending on product choice, installation quality, home design, climate, and maintenance. Comfort, noise, or efficiency outcomes can differ between properties, so it’s best to seek advice specific to your home and circumstances.
Not always. If your renovation is substantial – generally affecting more than 50 per cent of the volume of the existing building – you may need to comply with current NCC energy efficiency standards, including the 7-star requirement. For smaller projects, the obligations are typically less strict. A registered building surveyor can confirm what applies to your project.
It can be. Double glazing may help reduce draughts, limit heat loss in winter, and lower external noise. The level of improvement depends on factors like existing insulation, frame condition, and installation quality, but it’s generally considered one of the more effective upgrades for an older home’s thermal envelope.
You may be eligible. Under the Victorian Energy Upgrades (VEU) program, households with single-glazed windows can access discounts when upgrading to approved double glazed products. You’ll need to use an accredited provider and choose a product listed on the VEU register. Discount amounts vary based on the product, certificate price, and installation costs.
Retrofit glazing adds a second layer of glass or acrylic to your existing window, often via magnetic strips or a secondary frame. Full frame replacement removes the old window entirely and installs a new double glazed unit. Full replacement typically offers better thermal performance, while retrofit is often more affordable and can preserve the look of heritage windows.
It can, yes. Standard aluminium frames conduct heat readily, which can reduce the insulating benefit of double glazing. uPVC and thermally broken aluminium frames offer stronger thermal resistance, while timber is naturally insulating but needs more upkeep. The right frame choice depends on your climate, home type, and maintenance preferences.