Glazing: all the options and benefits
Today most new houses and additions will require double glazing to comply with the New Zealand Building Code.
Double glazing can make a big difference to comfort levels in your home. Combined with insulation in the walls, ceiling and floor, double glazing your windows and doors will help reduce heat loss, condensation on the glass, and heating and cooling costs.
The investment will be worthwhile — a warmer, healthier, quieter home with lower power bills. There's a lot to consider — speak with your builder, designer or window supplier about the best options.
The right glazing choices can help make your home more comfortable in both hot and cool weather whether you are building a new home or renovating.
It is worth considering retrofitting double glazing by replacing existing windows with double glazed ones, or by choosing another option such as fitting secondary glazing to existing windows.
The amount and orientation of glazing for your home will depend to a large extent on the climate and microclimate of your site. Wind, temperature, sun angles and proximity to the coast will all influence decisions about the size, type and placement of glazed areas.
There is a range of glazing options available. Some keep heat inside your home, others keep heat, noise, light and glare out.
If you're building new, or replacing window/door frames and the glazing, choosing the right frames will help you get the best performance out of your windows, skylights and glazed doors. The table on this page provides a basic comparison of the thermal performance of a small number of common glazing and frame combinations. The higher the R-value the higher the performance — less heat will transfer from one side to another. GLASS OPTIONS
There are many different types of glass available for double (and triple) glazing other than standard clear glass, including:
• Low-emissivity glass (also known as low-E glass) lets light and heat in, but helps prevent heat from escaping.
• Reflective glass, tinted glass and spectrally selective glass reduce the amount of heat and light that can get in, so are good at keeping summer heat out. The type of glass treatment determines whether infrared light (radiant heat), visible light or ultraviolet light is filtered out — ultraviolet light causes fading.
• Laminated glass consists of two sheets of glass bonded with a plastic or resin layer. It absorbs ultraviolet light and some heat and is the best option for reducing noise. If it's hit, the glass is held together by the resin layer.
• Toughened glass is much stronger than standard glass. It's designed to withstand direct impacts and to shatter into small chunks if broken.
Building Code clause F2.3.3 requires that glass that people are likely to come into contact with shall either break safely, resist impact or be protected by a barrier.
This glass must have a stamp on it to show that it is safety glass which meets the required standard.
You can make sure you have safety glass through the Ministry of Business, Innovation and Employment's Building Performance website, which has more information on how to check whether glass is safety glass. WHAT IS DOUBLE GLAZING?
A double-glazed window uses two panes, separated by a gap which is filled with air or an insulating gas such as argon. It is also known as an insulating glass unit (IGU).
Although gaps can vary between 6mm and 12mm, a 12mm gap is most common as it has the optimal insulation performance.
Argon gas is a better insulator than air, though slightly more expensive and in combination with low-E glass and high-performance frames can give an excellent thermal performance.
You can vary the glass you use for the two panes in a double glazing unit, and you can choose two different types of glass for each pane.
If you are retrofitting double glazing to your existing windows, there are three main options:
• Replacing the whole window frame with new frames.
• Installing double glazed inserts into your existing window frames — this is a cheaper option if your window frames are still in good condition.
• Installing temporary or permanent secondary glazing.
Low-E and tinted glasses can be included in these retrofit options. TRIPLE GLAZING
Triple glazing consists of three panes of glass separated by air gaps to provide comparatively high levels of heat retention and noise reduction. Triple glazing is an option for very noisy or very cold locations but is more expensive. NOISE REDUCTION
Glass is usually the weakest barrier to noise in the building envelope.
Standard double glazing provides a little improvement on single glazing for most sound frequencies but not always for low frequency noise.
Triple glazing is better again. If noise is a problem, options include using thicker and/or laminated glass — some laminated glass comes with a thick acoustic inter-layer — and increasing the air gap in double glazing.
Opening the windows will increase noise levels, so you'll need to consider the best way to manage ventilation if exterior noise is an issue.
Alternatively, consider secondary glazing. It can be a better option for blocking external noise — consult an acoustician for low frequency noise or traffic noise issues. R-VALUE
Standard aluminium with clear double glazing 0.26
Thermally broken aluminium with clear double glazing 0.31
Thermally broken aluminium with low-E, argon-filled double glazing 0.43
Timber or uPVC with clear double glazing 0.36
Timber or uPVC with low-E, argon-filled double glazing 0.53
Standard insulated wall construction R-value1.9 — SmarterHomes
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Otago Daily Times
01-07-2025
- Otago Daily Times
Glazing: all the options and benefits
Once you've insulated your ceiling, floors and walls, the next biggest culprits for heat loss are the windows and other glazing such as skylights and glass doors. Today most new houses and additions will require double glazing to comply with the New Zealand Building Code. Double glazing can make a big difference to comfort levels in your home. Combined with insulation in the walls, ceiling and floor, double glazing your windows and doors will help reduce heat loss, condensation on the glass, and heating and cooling costs. The investment will be worthwhile — a warmer, healthier, quieter home with lower power bills. There's a lot to consider — speak with your builder, designer or window supplier about the best options. The right glazing choices can help make your home more comfortable in both hot and cool weather whether you are building a new home or renovating. It is worth considering retrofitting double glazing by replacing existing windows with double glazed ones, or by choosing another option such as fitting secondary glazing to existing windows. The amount and orientation of glazing for your home will depend to a large extent on the climate and microclimate of your site. Wind, temperature, sun angles and proximity to the coast will all influence decisions about the size, type and placement of glazed areas. There is a range of glazing options available. Some keep heat inside your home, others keep heat, noise, light and glare out. If you're building new, or replacing window/door frames and the glazing, choosing the right frames will help you get the best performance out of your windows, skylights and glazed doors. The table on this page provides a basic comparison of the thermal performance of a small number of common glazing and frame combinations. The higher the R-value the higher the performance — less heat will transfer from one side to another. GLASS OPTIONS There are many different types of glass available for double (and triple) glazing other than standard clear glass, including: • Low-emissivity glass (also known as low-E glass) lets light and heat in, but helps prevent heat from escaping. • Reflective glass, tinted glass and spectrally selective glass reduce the amount of heat and light that can get in, so are good at keeping summer heat out. The type of glass treatment determines whether infrared light (radiant heat), visible light or ultraviolet light is filtered out — ultraviolet light causes fading. • Laminated glass consists of two sheets of glass bonded with a plastic or resin layer. It absorbs ultraviolet light and some heat and is the best option for reducing noise. If it's hit, the glass is held together by the resin layer. • Toughened glass is much stronger than standard glass. It's designed to withstand direct impacts and to shatter into small chunks if broken. Building Code clause F2.3.3 requires that glass that people are likely to come into contact with shall either break safely, resist impact or be protected by a barrier. This glass must have a stamp on it to show that it is safety glass which meets the required standard. You can make sure you have safety glass through the Ministry of Business, Innovation and Employment's Building Performance website, which has more information on how to check whether glass is safety glass. WHAT IS DOUBLE GLAZING? A double-glazed window uses two panes, separated by a gap which is filled with air or an insulating gas such as argon. It is also known as an insulating glass unit (IGU). Although gaps can vary between 6mm and 12mm, a 12mm gap is most common as it has the optimal insulation performance. Argon gas is a better insulator than air, though slightly more expensive and in combination with low-E glass and high-performance frames can give an excellent thermal performance. You can vary the glass you use for the two panes in a double glazing unit, and you can choose two different types of glass for each pane. If you are retrofitting double glazing to your existing windows, there are three main options: • Replacing the whole window frame with new frames. • Installing double glazed inserts into your existing window frames — this is a cheaper option if your window frames are still in good condition. • Installing temporary or permanent secondary glazing. Low-E and tinted glasses can be included in these retrofit options. TRIPLE GLAZING Triple glazing consists of three panes of glass separated by air gaps to provide comparatively high levels of heat retention and noise reduction. Triple glazing is an option for very noisy or very cold locations but is more expensive. NOISE REDUCTION Glass is usually the weakest barrier to noise in the building envelope. Standard double glazing provides a little improvement on single glazing for most sound frequencies but not always for low frequency noise. Triple glazing is better again. If noise is a problem, options include using thicker and/or laminated glass — some laminated glass comes with a thick acoustic inter-layer — and increasing the air gap in double glazing. Opening the windows will increase noise levels, so you'll need to consider the best way to manage ventilation if exterior noise is an issue. Alternatively, consider secondary glazing. It can be a better option for blocking external noise — consult an acoustician for low frequency noise or traffic noise issues. R-VALUE Standard aluminium with clear double glazing 0.26 Thermally broken aluminium with clear double glazing 0.31 Thermally broken aluminium with low-E, argon-filled double glazing 0.43 Timber or uPVC with clear double glazing 0.36 Timber or uPVC with low-E, argon-filled double glazing 0.53 Standard insulated wall construction R-value1.9 — SmarterHomes
Newsroom
08-06-2025
- Newsroom
Why we should let our buildings die a natural death
Comment: There is one universal goal every architect and builder works towards when they undertake the task of designing or building a home in Aotearoa: comply with the New Zealand Building Code. I have shared in this ambition as a licensed builder, working on projects in Wellington for the past nine years. But in my years of striving to do this, I have had to work with timber saturated in chemical preservatives, adhesives riddled with dangerous compounds, and paints that leave behind a legacy of microplastics. Despite their toxic nature, these are the materials we're using to build 'durable' and 'healthy' homes. This is not an experience unique to me: this is the experience of all builders, whether they are aware of it or not. A 2021 WorkSafe survey found that construction workers have the highest average number of exposures to carcinogenic (cancer-causing) substances, out of 30 professions examined. The irony is undeniable: in striving to meet durability standards, we have normalised the use of materials that compromise human wellbeing and the environment we are striving to protect. Designing differently Wrestling with these issues, I was motivated to return to study and complete my Master of Architecture degree. My thesis explored design for disassembly (DfD) as an alternative to conventional durability standards. DfD challenges the notion of permanence by proposing that buildings should be conceived with their eventual deconstruction in mind. As such, it offers a way of building that does not rely on chemical toxicity to achieve longevity but instead does this by replacing elements when they've reached the end of their life. In practice, this might involve framing systems where individual studs and beams are removable and able to be repurposed without the need to demolish entire structures. It could also involve cladding that can be demounted and replaced rather than being permanently lathered in toxic coatings. Materials would be joined with screws, bolts, or clips – rather than nails—allowing them to be separated at the end of their useful life. During my research, I created a 1:1 scale model of a section of a building using a DfD approach. This model used untreated pine alongside materials salvaged from various building sites and recyclers. This scale model supports the idea that DfD is possible in the context of our existing construction industry. However, such an approach would present a fundamental challenge to how we build now. We have conditioned ourselves to believe that fighting natural decay is necessary to achieve good building outcomes. But by forcing materials such as timber to resist their natural cycle of decay, we are creating long-term environmental hazards. Carcinogenic preservatives such as copper chrome arsenate (CCA) don't simply disappear once a building reaches the end of its life. They continue to leach into soil, water, and air, leaving a significant problem for us and future generations. A lot of CCA-treated timber ends up in landfill. It's estimated that 50 percent of waste sent to landfill each year comes from construction and demolition activities, with about a third of this waste being timber. Although builders bear the brunt of exposure to treated timber, residents can also be exposed. Treated-timber products are often hiding in plain sight in decks and cladding. Many occupants are likely to have no idea that the structures sheltering them are built with materials that contain harmful chemicals. Where to from here? Our current system asks builders and residents alike to pay the price for durability standards that have failed to evolve alongside our knowledge of health and environmental impacts. This growing knowledge has led other jurisdictions, such as Australia, the EU, and US, to ban or restrict the use of CCA. The idea of reducing timber treatments may leave architects and builders reeling, particularly given the leaky homes' legacy still weighs heavily on the industry. However, at least in part, it's our reliance on non-durable pine that has forced our reliance on treatments such as CCA. DfD provides the opportunity to consider both alternative non-toxic timber treatments and alternative timbers. But for DfD to truly take hold, a shift must begin at the point where buildings are conceived: their design. We need to question not just our approach to design, but our planning of spaces to accommodate the demands of DfD. There are plenty of examples from other countries that show how this problem can be tackled. For example, German architects C/O Now's project 'Where the wild morels grow' designed a residential building drawing on concepts of biophilic design and deconstruction. Biophilia in architecture aims to more closely integrate humans and nature. This project used the idea of a house built within a climate envelope (a house and garden sheltered by an external 'shed'). Of course, architects alone cannot achieve a switch to DfD. Considerable change is also needed within the entire building industry. Building regulations also need to evolve to encourage and reward circularity that considers end-of-life consequences, rather than measuring success through arbitrary lifespan targets for buildings and building components. In addition, material suppliers must increase access to non-toxic, renewable, and recyclable products. Likewise, builders need to be open-minded and support new construction concepts and techniques that may be unfamiliar to them. And lastly, everyone who has the privilege of owning a house needs to understand the impact they can have by choosing to support low-toxic solutions when considering renovating or building. It is time to let our buildings die a natural death and in doing so, give life back to the future of architecture.
Otago Daily Times
24-04-2025
- Otago Daily Times
Restoration a balance of two worlds
This Dunedin villa addresses the importance of heritage preservation and the need to improve our housing stock to be fit for modern life and future generations. It was recently shortlisted for the southern architecture awards, Kim Dungey reports. Located on a street lined with highly-detailed timber gable houses, this 1920s villa has been lovingly restored to maintain its public presence and extended to better take advantage of its dynamic surroundings. "We call the house 'The Weather Watcher' because you can see all the storms that come up the valley," owner, designer and carpenter Tony Calder says. While he and partner Julia Smith wanted to experience the changes in season, it's not like they feel exposed to the elements; the alterations have transformed the once-cold Dunedin villa into a warm and comfortable home. The couple bought the Belleknowes property sight unseen while living in Amsterdam. It was only when they returned to New Zealand that they realised there was potential to capture the sweeping views — over Kaikorai Valley and out to the ocean — and decided to renovate. At that stage, there was a separate lounge off the central hallway and a tiny kitchen at the back. The bathroom in the home's northwest corner was the only area to get a reasonable amount of sun and none of the rooms opened up to the view. A coin found lodged in behind a door frame suggested the house was built in about 1921, according to Mr Calder, a director of local architectural practice ahha Architects, who drew up plans for the alterations and did almost all the work himself. "It was in a bit of a state. It hadn't had any maintenance done and the last renovations had been in the 1980s or '90s.""Parts of the house we thought would be in an OK condition weren't. So we replaced a lot of the framing, the weatherboards and the roof," he says, adding the interior was largely gutted and only the two front bedrooms remained in their original position. Heritage elements were restored and celebrated, rotten floors and window frames were replaced and the back of the house was pushed out by 3.5m to give more living space. Clad in macrocarpa and leading to a new deck, the extension has windows carefully placed to capture the northwestern sun. It's cantilevered over a large flexible space below, which was created by supporting the house on props and digging underneath. Again, the weather was a consideration: "There was a wee bit of nervousness when it was just sitting on stilts because we get strong winds that come up the valley and you could feel the whole house shaking." Now 50% bigger than before at 180sq m, the house is also air-tight and well-insulated, with thermally-broken double glazing. Mr Calder says there are several ways to meet the New Zealand Building Code but his practice thermally models everything because it is the only way to accurately predict what will happen. "With thermal modelling, we've checked the size and placement of glazing and increased the amount of insulation in the house, increasing construction costs by around 2%. However, the house uses half of the energy a typical new build would use, giving a payback period of a year." Working on the house highlighted the need for much of Dunedin's building stock to be updated, he adds. "Dunedin has a lot of unchanged villas that ignore their environment and haven't had sufficient maintenance. There's an amazing opportunity to explore simple renovations which provide better access to the outside and increase the buildings' performance for a comfortable interior living experience, while maintaining their character value." When it comes to the interior, many of the new details reflect those in the ceilings and the facade of the old villa. There's a curved wall leading into the kitchen and an arch that is a contemporary take on the one originally in the hall. Mr Calder built the kitchen and bathroom cabinetry from miro, a native timber recovered from naturally-fallen trees. The panelling and built-in furniture in the extension are gaboon plywood and, referencing the home's 1920s origins, the main bathroom is tiled in terrazzo. Prioritising circular construction, timbers salvaged from the demolition were used throughout the house. Like many villas, this one originally turned its back on the views and light and had no connection to the landscape. Now it capitalises on its vantage point, allowing the owners to watch the weather rolling in while enjoying a warm, contemporary home. "I'm happy with how it takes in the wider context and positions you to feel connected to the place that you are," Mr Calder says. Before and After The alterations opened the house up to the sun and views, with flexibility to allow for changing needs. The plans below show the changes made to the upper floor.
