I think we need a powerful overall introduction to the WINDOWS/DOORS section here. Maybe one or two paragraphs, keeping it simple... but just enough to lead people into this section?
I think we need a powerful overall introduction to the WINDOWS/DOORS section here. Maybe one or two paragraphs, keeping it simple... but just enough to lead people into this section?
WHY WINDOWS MATTER
Benji Simmons: Stärke Windows
“We do windows and doors because of the effect it has on the building performance – the most significant elements... Up to 50% of heat loss and up to 70% of heat gain is through your windows.”
Brent & Claire Chatterton: Chatterton Homes
“Windows can contribute to heat loss through thermal bridging, and allow uncontrolled air movement through inadequate seals, which encourages draughts and allows allergens and moisture into the home. High performing windows mitigates these risks through better seals and the use of less conductive materials.”
Julie Villard: Eco Design Advisor Christchurch City Council
“Windows can contribute significantly to a building’s heat losses... They need to multi-task, bringing in light, allowing solar gain as free heat, and limiting heat loss in winter.”
Bob Burnett: Superhome Movement Co-founder
“I’m really interested in achieving better performance with the windows because that’s where most of the heat loss is.”
Darren Ballantine: Metro Glass
“Any change in improving the efficiency of a home is a step in the right direction – windows are acknowledged as being a leading cause for both the loss of heat out of a home as well as contributing to heat gain – so the windows are also a leading opportunity to gain thermal performance within a home and make it a more satisfying and happier place to live in.”
U-VALUES & R-VALUES EXPLAINED
These value numbers indicate how much glass (or other building materials) retains or conducts heat. The U-value is commonly used for glass and window performance.
Andrew Krupa: Koffman Windows
“The R-value, or thermal resistance rating’ measures the effectiveness of a product or material in slowing down the transfer of heat. The larger the R-value, the more effective a product is at stopping the transfer of heat and the better insulated the material is. Put simply, the higher the R-value, the better the material is at insulating your home.
The U-value measures thermal transmittance, the rate of heat loss or gain through a structure or material. The lower the U-value, the better the material is at stopping the transfer of heat and the better insulated the material is.
The R-value measures thermal resistance through a material, the U-value measures thermal conductivity. They are mathematically inverse of one another.”
RECESSED WINDOWS
THE PROBLEM:
Current NZ Building Code requirements were developed primarily to deal with the risk of windows not being watertight, positioning windows out over an exterior wall cavity to prevent water getting in.
BUT this places the window frame and glass outside the insulation line, in the colder part of the wall.
In autumn and winter, this keeps the frame and glass colder, losing heat and generating condensation on both the frame and the glass.
The current NZ Building Code does not include any requirements to address summer overheating.
THE SOLUTION:
Recessing the window frame in line with the insulation in the wall is a simple change that protects the frame and glass from external temperatures. This basic change will bring huge improvements to the home:
● Reducing heat loss in winter
● Reducing condensation and moisture buildup in the home and so reducing the risk of mould
Benji Simmons: Stärke Windows
“The warm barrier down the middle of the glass and down the middle of the frame needs to be CONNECTED to the warm barrier of insulation in your wall.”
Andrew Krupa: Koffman Windows
“Windows should be recessed into the wall where the thermal barrier of the window is connected to the thermal barrier of the wall. Recessed installation does not require specific builders, tools, or any extra certifications. The reason why most windows aren’t recessed installed is because there is a lack of awareness and readiness to change from old methods.”
Benji Simmons: Stärke Windows
“Nearly all windows in NZ are installed the wrong way, and it remains the default setting the the Building Code. This issue has arisen very uniquely in the NZ market due to the way the Building Code works, the products which have been available, and the industry knowledge around thermal performance... and it’s time we all fixed it!
Recessed window installation is NOT greatly more expensive, nor more complicated, than old-fashioned Building Code installation.”
Dan Saunders, Dan Saunder Construction demonstrates installing a recessed window, 2024 SUPERHOME TOURS
DOUBLE & TRIPLE GLAZING
The Superhome Movement’s BASE / BETTER / BEST criteria give you options for your windows – depending on your particular needs, goals and budget, which temperature zone you’re in, and the design of your home.
The area of windows, and how the windows are oriented to the sun, will affect heat retention. Double glazing is a requirement for Superhome BASE certification. Triple glazing is recommended for BEST certification.
Darren Ballantine: Metro Glass
“Older single glazing is often responsible for half of all heat lost. Standard double glazing is up to 52% more efficient than single glazing at retaining heat and keeping out the cold. Triple glazing has U-values up to 82% higher than standard double glazing – significantly reducing the energy demand for heating and cooling a home, by maintaining a more consistent temperature year round.”
Martin Ball: NK Windows
“Most new houses and additions will require double glazing to comply with the NZ Building Code. For renovation, if you don’t require consent, double-glazing isn’t mandatory, but is worth considering for improved warmth and energy efficiency. Triple glazed windows offer even better thermal performance.”
WHAT IS ARGON?
Argon is now commonly used in double and triple glazing to provide additional levels of insulation in the window unit.
Argon is a dense gas that slows down the rate of heat transfer through the panes of glass, acting as a thermal insulator. Low-E glass is important as it reflects a higher percentage of heat back into your home than standard uncoated glass. In summer it reflects heat from the sun back outside, helping keep the interior cool. In the winter, it reflects heat back into the room, helping to keep it warm.
Argon not only acts as an insulator but also ensures even temperature distribution across the window, reducing the likelihood of condensation. Argon-filled double-glazed glass in a uPVC frame is typically 50-60% more energy efficient than single-glazed glass.
WINDOW FRAMES
Options for high efficiency high performing window frames include thermally broken aluminium, uPVC and timber – imported European technologies or NZ made. Each has different qualities, values and requirements.
Darren Ballantine: Metro Glass
“Each of these choices comes with their own set of considerations, and that is where a reputable and engaged window advisor can greatly assist in making the best choice to suit the individual requirements of the homeowner, having listened to and considered your individual needs, wants and of course budget.”
Andrew Krupa: Koffman Windows
“Heat can also be lost by convection through the cavities and conduction through the frame of the window. A thermally broken window has a non-thermally-conductive material inserted into the aluminium frame in a way that disrupts the transfer of heat. By interrupting the flow of heat through the frame, thermally broken windows significantly reduce heat loss during the colder months and heat gain during the summer months.”
THE GLASS
The glass itself is hugely important and can make an enormous difference to the performance of your windows and the experience of living in your home.
Darren Ballantine: Metro Glass
“The glass in double and triple glazing is not just glass.
There are many ways we can help solve a problem or provide a benefit with the wide range of glass coatings and tints now available – using a combination of low-E and different glass types for:
• Insulative gains
• Solar control to protect against overheating or alternatively to let maximum heat in (passive heat gain)
• Letting light in to a home or alternatively cutting down on glare
• Protecting furnishings, carpet and other items of value from UV
• Lowering noise levels
• Privacy, security and added safety.”
The glass itself is hugely important and can make an enormous difference to the performance of your windows and the experience of living in your home. Clear-on-clear double glazing may look like a good investment, but this technology is now completely outdated considering the additional performance Low Emissivity Glass with Thermal Spacers, Argon Filled can provide to a home’s performance at little additional cost.
WHAT IS LOW-E GLASS?
Low Emissivity Glass – Low-E glass is very energy efficient with a special coating that lets in light while retaining heat inside to help maintain indoor comfort levels. It can reduce heat loss by up to 61% compared to standard double glazing. If overheating is risk for your home in the hot summer months, solar control low-E glass options can help to reduce solar heat by up to 71% when compared to standard double glazing.
Low-E is a sophisticated technology that revolutionises the thermal performance of your windows. It acts as a thermal barrier. It also reduces the transmission of UV light which can bleach furniture. In winter, it reflects heat back inside, minimising radiant heat loss. In summertime, it reverses the game, keeping your home cooler and more comfortable. Argon is now commonly used in double and triple glazing to provide additional levels of insulation in the window unit.
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