High-Performance Aluminium Windows for Passive Design: Orientation, Shading and Airtight Interfaces

Passive design is the practice of shaping a building so that it manages heat, light and air largely through its own form, orientation and envelope before mechanical systems are asked to make up the difference. For an architect, builder or owner in Australia or New Zealand, the window and door package is where that ambition is either delivered or lost. Glazing is the thinnest and most thermally exposed part of the envelope, it faces the sun for much of the day, and it is interrupted by openings that must still close tightly. A passive-design project therefore treats aluminium windows and doors as engineered envelope components rather than as a finish selection, and it coordinates their orientation, shading, glazing, framing, airtightness and installation as a single system.

This article sets out how that system comes together. It explains how orientation and shading govern solar gain, how thermal breaks and Low-E double or triple glazing control conduction and radiation, how airtightness and ventilation are balanced, how frames and reveals are detailed, and how installation interfaces decide whether the designed performance survives contact with a real wall. It also covers how compliance works under the NCC and the relevant Australian and New Zealand standards, and why energy claims for any window system must remain project-specific. Meichen International Windows & Doors (MC Windows) has supplied high-performance aluminium window and door systems to the Australian and New Zealand market since 2017, drawing on 18 to 19 years of industry experience and a 20,000 sq m manufacturing facility, and its product range illustrates the choices described here.

What Passive Design Means for a Window and Door Package

Passive design is a design method, not a product category. It sets out to keep occupants comfortable using the building’s own fabric: its orientation, its insulation, its thermal mass, its shading, its airtightness and its ability to ventilate naturally. Heating and cooling equipment is then sized to handle the residual load rather than the whole load. In that method, every envelope element has a defined job, and the window package has the hardest job of all because it must simultaneously admit daylight and view, exclude or admit solar radiation as the season requires, resist wind and rain, control sound, and allow the building to breathe when that is wanted and to stay sealed when it is not.

A window is therefore never judged on one number. A unit that performs beautifully in winter in a cool climate can overheat a living room in summer if its shading is wrong, and a unit with excellent glazing can still underperform if the frame is unbroken aluminium or if the gap around it is sealed with expanding foam and hope. Passive design asks the project team to think in terms of the whole assembly: glass, spacer, frame, thermal break, seal, reveal, insulation and wall junction.

The three paths by which a window gains or loses heat

Heat moves through a window assembly by three routes, and each is controlled by a different part of the specification.

Conduction and convection move heat through the glass, the spacer and the frame. Double and triple glazing reduce this by trapping still air or gas between panes, and thermal break frames reduce it by interrupting the aluminium path.
Radiation moves heat as invisible light. Low-E coatings change how much long-wave radiation the glass reflects back into the room or out to the sky, which is why coating selection is central to both winter heat retention and summer heat rejection.
Air leakage moves heat and moisture as bulk air through gaps at sashes, meeting stiles, tracks, hardware penetrations and the perimeter junction with the wall. It is the least visible path and often the most damaging, because it also carries water vapour into the assembly.

Passive design works when all three paths are addressed at once. Improving glazing while leaving an unbroken aluminium frame and a poorly sealed perimeter produces a package whose measured performance falls well short of the sum of its parts.

Why the envelope carries more of the load as buildings improve

As walls, roofs and floors become better insulated, the window share of the total heat flow rises, even though the window itself has improved. This is simple arithmetic: once the opaque envelope is doing very little, the remaining weak point dominates the result. It is the reason passive-design projects tend to specify better glazing and more careful installation than code-minimum projects, and the reason a small number of badly installed units can disproportionately affect a whole house. The same logic applies to airtightness, where a handful of unsealed penetrations can undo the work of sealing everything else.

Orientation: Designing the Openings Around the Sun Path

Orientation is the first and cheapest passive-design decision, and it is made before any window is specified. The sun’s path across the sky changes through the year, rising higher in summer and tracking lower in winter, and the difference between those two arcs is the free heating and cooling resource the design should exploit. In the southern hemisphere, north-facing glass receives useful winter sun at a low angle and can be shaded in summer by a correctly sized eave or horizontal device. East and west glass receives low-angle sun in the morning and afternoon, when the sun is difficult to shade and the heat gain is intense. South glass receives little direct sun but is exposed to cold winter winds and steady diffuse light.

A passive-design plan therefore places living spaces where they can benefit from northern winter sun, keeps bedrooms and utility spaces to the south or east where heat gain matters less, and treats west glass as the most demanding orientation because afternoon sun arrives low and hot. This is a design intention, not a rule that can be applied mechanically; a site with a restricted outlook, a heritage frontage, an overshadowing neighbour or a strong prevailing breeze will force trade-offs, and the window package has to be specified for the orientation that actually results.

Matching glazing to orientation rather than to the whole house

One of the most common specification errors is to apply a single glazing type across an entire dwelling. A coating and glass combination chosen to keep west heat out will also reduce the winter solar gain that a north window was designed to capture. Where the budget or the design allows, the glazing schedule should differentiate by orientation: different solar control on the west, more solar admission on the north, and a neutral, well-insulated specification for south glass where heat loss dominates and heat gain is rarely wanted. The same logic applies to the frame: thermally broken framing matters most where the indoor-outdoor temperature difference is greatest and where the frame area is largest.

Glazing area, room function and the limits of glass

Passive design does not mean maximising glass. Every square metre of glazing is a square metre of envelope with a much lower thermal resistance than the adjacent wall, so the ratio of glass to solid wall is a design variable with real consequences. Large openings suit living areas with good solar access and effective shading; small, well-sealed and well-insulated openings suit bathrooms, laundries and circulation spaces. The right answer depends on the climate zone, the shading design, the thermal mass available and the way the occupants actually use the rooms, and it should be tested in the project’s energy model rather than assumed from a generic target.

Shading: Fixed, Adjustable and Landscape

Shading is the most cost-effective passive cooling measure available, because it blocks solar radiation before it becomes heat inside the building. It also protects the glazing and frame from the worst of the sun, which reduces thermal stress on seals and coatings. Shading design has to be seasonally selective: it should admit winter sun when the sun is low and the heat is welcome, and exclude summer sun when the sun is high and the heat is not.

Fixed shading and the geometry that makes it work

Fixed devices include eaves, horizontal blades, vertical fins, pergolas and deep reveals. Their effectiveness depends on geometry: the projection depth relative to the window height, the orientation of the façade, and the sun angles at the site’s latitude. A correctly designed eave on a north façade can exclude high summer sun while admitting low winter sun with no moving parts and no maintenance. Vertical fins work better on east and west elevations, where the sun arrives low and from the side, and horizontal devices on those elevations are much less effective. Because the geometry is fixed, it must be resolved early, before the roof line and the window head height are locked in.

Adjustable shading, internal blinds and the low-angle sun problem

External adjustable devices such as louvres, shutters and retractable screens can respond to conditions and to occupant preference, and they are particularly useful on west elevations where fixed geometry struggles. Internal blinds and curtains are valuable for privacy, glare and night-time insulation, but they are a poor substitute for external shading because the radiation has already passed through the glass and become heat inside the room. The most robust approach is layered: fixed or external shading as the primary defence, operable devices for the difficult orientations, and internal blinds for glare and privacy.

Meichen’s range includes louvre systems alongside its window, door and curtain wall lines, which allows a project to coordinate shading and glazing as one visual and technical family. Landscaping, mature deciduous trees and adjacent built form also shade a façade, and they should be considered in the same analysis because they change over the life of the building.

Solar Gain and Glazing Selection

Solar gain is the heat that enters a building as sunlight passes through glass and is absorbed by floors, walls and furniture. In a heating-dominated climate it is a free heat source; in a cooling-dominated climate it is a load to be rejected. Passive design manages the balance rather than maximising or minimising either side, and the glazing specification is where that balance is written down.

Low-E coatings and what they actually do

A Low-E, or low-emissivity, coating is a microscopically thin metallic layer applied to a glass surface. It changes the surface’s ability to radiate heat, so that long-wave radiation from inside the room is reflected back rather than transmitted through the glass. In a cold climate this keeps heat in the room; in a hot climate, combined with the right coating position and glass combination, it helps limit heat entering. Coatings interact with the gas fill, the spacer and the glass thickness, so a Low-E label alone says nothing about performance. The project’s glazing schedule should define the full build-up, and the supplier should confirm what is being supplied against that schedule.

Double and triple glazing: what the extra pane buys

Double glazing creates a sealed cavity between two panes, and triple glazing adds a second cavity and a third pane. Each cavity reduces conduction and convection through the assembly, and each additional pane adds a surface that can carry a coating, which is why triple glazing is usually specified where winter heat loss dominates and where external noise is a concern. The gains are not linear: the first cavity delivers the largest improvement, and each subsequent step buys less while adding weight, depth and cost. Triple glazing also requires deeper frames and heavier hardware, which must be coordinated with the wall thickness and reveal depth at the design stage rather than discovered on site.

Balancing daylight, view and heat

Glazing selection is a three-way negotiation between daylight, view and thermal load. Tinted or heavily coated glass can reduce heat gain but also reduces daylight and can change the colour of the view, which occupants notice immediately. Highly transparent glass admits daylight beautifully but may overload a west-facing room. The right balance is climate-specific and room-specific, and it is best resolved by testing options in the energy model and reviewing sample units in place, under real sky conditions, before the order is placed.

Thermal Breaks in Aluminium Frames

Aluminium is an excellent structural material and a very good conductor of heat. An unbroken aluminium frame therefore acts as a thermal bridge, short-circuiting the insulation of the wall and creating a cold internal surface where condensation forms and comfort drops. A thermal break solves this by separating the inner and outer parts of the profile with an insulating element, usually a polyamide strip, so that heat must cross the insulator rather than the metal.

How a thermal break is constructed

In a thermally broken profile, the extrusion is produced in two parts and joined by a structural insulating strip that is crimped or rolled into the aluminium. The strip carries the structural load between the inner and outer sections while interrupting the conductive path. The quality of that connection, the width of the strip and the way the profile is assembled all affect performance, which is why thermal break claims should be supported by test evidence for the specific system rather than by a general statement about the material.

Meichen’s thermally broken systems include the MC140 sliding door and the MC100 series, which covers awning, fixed, tilt and turn, and double hung configurations. Its non-thermal-break ranges, such as the MD150 series and the ApexAwning 100/150-AS960, serve applications where a thermal break is not required by the project brief. Specifying the right family for the application is a design decision, and it should be made against the project’s thermal targets, not against price alone.

Where thermal bridging hides in a window assembly

The frame profile is only one part of the bridge. The edge spacer that separates the panes in an insulating glass unit is a small but continuous conductive path around the perimeter of every pane, which is why warm-edge spacers are specified in cold climates. The interface between the frame and the wall is another: a steel lintel, a concrete reveal or an uninsulated sill can conduct heat past the window even when the window itself performs well. Hardware, fixing brackets and structural connections can also create local bridges. A passive-design detail closes these paths rather than treating the window as an isolated product.

Airtightness: The Quiet Variable in Passive Performance

Airtightness describes how well the envelope resists uncontrolled air movement. It is separate from ventilation, which is deliberate air movement provided on purpose. A building can be very airtight and very well ventilated at the same time, and a passive-design building needs to be both: tight enough that the designer controls where air enters and leaves, and openable or mechanically ventilated enough that indoor air quality stays healthy.

Air leakage matters for three reasons. It carries heat out in winter and in during summer, so it undermines insulation and glazing performance. It carries water vapour into wall and roof cavities, where it can condense unseen. And it bypasses filtration, so it brings in pollen, dust and noise. In a window package, leakage occurs at sash and frame junctions, at sliding tracks and meeting stiles, at hardware penetrations, and around the perimeter where the frame meets the wall. The last of these is an installation issue rather than a product issue, and it is the one most often left to chance.

Where window and door leakage actually happens

Sash and frame junctions, where seals must compress consistently along the whole perimeter rather than only at the corners.
Meeting stiles and interlocks on sliding and bi-fold units, where two moving panels come together and the seal is intermittent by nature.
Tracks and drainage paths, which must let water out without letting air in freely.
Hardware and lock penetrations, which are small but numerous.
The perimeter junction, where the frame meets the wall, the flashing and the air barrier, and where continuity between three different trades is required.

Meichen’s systems are designed with sealing at the frame and meeting edges as a core part of the assembly, and the company describes its air tightness as excellent for both acoustic and thermal insulation. As with every performance attribute, the value achieved on a project depends on the specific system, the size of the unit, the installation quality and the surrounding wall construction, and it is confirmed through the project’s testing and documentation rather than assumed from a brochure.

Verifying airtightness rather than assuming it

Verification is usually done by a whole-building pressure test, in which the completed envelope is pressurised or depressurised and the resulting airflow is measured. The test identifies whether the target has been met and, with a smoke or thermal-imaging survey, where the leaks are. In Australia, whole-of-house pressure testing is not universally mandated for detached housing, but it is increasingly specified by clients, energy consultants and green building rating tools, and it is normal practice on projects targeting very high performance. The practical lesson for the window package is that sealing should be inspected and photographed before linings close, because the most important defects are the ones that become invisible.

Ventilation: Deliberate Air Movement in a Tight Envelope

Once a building is airtight, ventilation must be designed rather than left to leakage. Passive design prefers natural ventilation where climate and site allow, because it uses no fan energy, and it relies on two driving forces: wind pressure on the façade and the buoyancy of warm air rising. Cross ventilation, where openings on opposite or adjacent sides allow air to pass through a room or a dwelling, is far more effective than a single opening, and it depends on the window schedule as much as on the plan.

Operable types and how they support airflow

Different operable types suit different ventilation tasks. Awning windows open outward from the bottom and can remain open in light rain, which makes them useful for bathrooms and for rooms occupied during wet weather. Casement windows open outward on a side hinge and can catch breeze from a particular direction. Double hung windows allow controlled opening at the top and bottom simultaneously, which supports stack ventilation within a room. Sliding doors and stacker doors provide large openings for cross ventilation and for connecting living areas to outdoor space, while tilt and turn units offer a restricted opening for secure night ventilation and a full opening for cleaning and access. Meichen’s MC100 series covers awning, fixed, tilt and turn, and double hung configurations, and its sliding and bi-fold ranges include the MC140 sliding door, the MA73 no-mullion bi-fold door and the Ultra Slim Coastal SD205-AS960 sliding and stacker doors.

Night purge, security and the shoulder seasons

Night purge ventilation uses cooler night air to remove heat stored in the building fabric during the day, and it is most effective when openings are large, secure and protected from rain and insects. It also requires thought about security: a fully open window on a ground floor at night is a risk, which is why restricted openings, lockable stays and screened openings matter. In the shoulder seasons, when neither heating nor cooling is running, operable windows and doors are often the only conditioning the building needs, and a passive-design plan that provides generous, well-placed openings in living areas can substantially extend the period in which the house runs on natural ventilation alone.

Condensation: The Visible Symptom of a Thermal Problem

Condensation forms when moist air meets a surface cold enough that the air can no longer hold its moisture. In a window assembly it appears in two places, and the two have different causes and different remedies.

Surface condensation on glass and frames

Surface condensation on the room-side of glass or frame is a comfort and durability problem. It indicates that the internal surface is colder than the dew point of the indoor air, which in turn points to either a poor thermal specification or a moisture load that is too high for the ventilation rate. Better glazing and a thermally broken frame raise the internal surface temperature and reduce the risk. Reducing internal moisture from bathrooms, kitchens and laundry, and providing consistent ventilation, addresses the other half of the equation. It is important to understand that a better window does not eliminate condensation if the building is humid and under-ventilated; it simply moves the threshold.

Interstitial condensation and sealed cavities

Condensation inside the glazing cavity or within the wall assembly is more serious because it is hidden. Sealed insulating glass units are factory-sealed and should remain dry; visible internal fogging indicates a failed seal, and the unit should be replaced rather than cleaned. Within the wall, moisture carried by leaking air or by diffusion can condense on cold surfaces such as lintels, flashings or the back of the frame, and the resulting damage may not appear for years. The prevention is a continuous air barrier, correct placement of vapour control layers for the climate, and detailing that allows any incidental moisture to drain and dry.

Frames and Reveals: The Detail That Decides the Outcome

The frame is the visible structure of the window and the hidden structure of its performance. Frame depth, profile width, thermal break construction and the way the frame sits within the wall all affect how much glass area is available, how much heat crosses the junction and how the building looks from inside and out.

Slim profiles without a performance penalty

Narrow sightlines are a design priority on many projects because they maximise glass and view, particularly in coastal and landscape settings. The concern is that slim profiles are sometimes assumed to be weaker or less thermally efficient. In practice, modern extrusion design allows a narrow visible face while retaining a deep structural section and a thermal break behind it. Meichen’s Ultra Slim Coastal SD205-AS960 sliding and stacker doors and the SLMA100-20 slim sliding window are examples of this approach within a range that also includes the deeper MC100 and MC140 systems. The right choice depends on span, wind load, glass weight and the required thermal performance, all of which are confirmed against the project’s structural and energy documentation.

Reveals, sills and insulation continuity

The reveal is the return surface between the window frame and the inner face of the wall. It is a small area with a large effect, because it is where the insulation, the air barrier, the frame and the internal lining must all meet. Common defects include insulation stopping short at the frame, a gap between the frame and the stud that is bridged only by plaster, and a sill that is not sloped or drained. A good reveal detail continues the insulation to the frame, seals the air barrier to the frame with a compatible flexible sealant or membrane, provides a drained and ventilated cavity where the cladding system requires one, and leaves a clean, paintable or plasterable surface inside. On thermally broken systems the reveal is also where the benefit of the break is preserved; if the frame is surrounded by uninsulated structure, the break is bypassed.

Installation Interfaces: Where Design Performance Is Won or Lost

Installation is the point at which a tested product becomes a building element, and it is where most performance failures originate. The interface between window and wall involves tolerances, structural fixing, weather sealing, air sealing and finish, and each of those is owned by a different trade on most sites.

The opening, the tolerance and the fixing

Structural openings are built to tolerances, and frames are manufactured to tolerances, and the two do not always agree. The design must allow for the realistic variation in the opening, for the frame to be set plumb, level and square, and for the fixing to transfer wind load to the structure without distorting the frame. Packing and shimming must be placed at fixing points rather than at mid-span, and fixings must be appropriate to the substrate and protected against corrosion in coastal environments. Distortion of a frame during installation is a common cause of poor sash operation and seal leakage, and it is entirely avoidable with a documented installation sequence.

Flashing, sealants and the air barrier

Weather sealing at the perimeter is a layered system, not a single bead of sealant. Flashing at the head, sill and jambs must shed water outward and integrate with the wall’s drainage plane. The air barrier must be continuous from wall to frame, which usually means a flexible membrane or sealant joint that accommodates movement rather than a rigid connection that cracks. Sealant joints must be correctly sized, with the right backing and the right bond breaker, and they must be compatible with the frame finish and the adjacent materials. Sealant is a movement-accommodating weather seal, not a structural adhesive and not a substitute for flashing.

AS 4666 and the discipline of documented installation

AS 4666 addresses the installation of windows and doors in buildings and provides the framework for installation that preserves the performance established under AS 2047. For a passive-design project, the practical value of working to a recognised installation standard is that it makes the interface inspectable: the sequencing, the fixings, the flashing and the sealing are defined, so they can be checked before they are covered up. Installation should be recorded with photographs at each stage, because the evidence is needed if a leak or a draught appears later.

Compliance: NCC, ABCB and the Standards Framework

In Australia, the National Construction Code sets the minimum regulatory requirements for buildings, and it is maintained by the Australian Building Codes Board. The NCC’s energy efficiency provisions for commercial buildings are commonly known as Section J, while residential energy efficiency requirements sit in the residential volumes and are assessed through tools such as NatHERS or deemed-to-satisfy provisions. The NCC does not specify a particular window product; it sets performance outcomes and references standards and rating methods that demonstrate compliance, and the project’s building surveyor or certifier confirms the pathway.

The Australian standards that govern the product

AS 2047 is the product standard for windows and external glazed doors in buildings, and it defines the performance characteristics that a window or door must satisfy for its application, including structural performance, water resistance and air infiltration. AS 4284 is the test method used to establish water penetration performance for façades and window assemblies, and testing under it produces the performance levels quoted for a system. Meichen’s products are tested for water tightness under AS 4284 with performance of up to 960 Pa, which the company describes as setting an industry benchmark. That figure is a test result for the tested configuration, and the appropriate rating for a given project still depends on its wind loading, height and exposure.

AS 1288, Glass in buildings, governs the selection and installation of glass, including the determination of glass type and thickness for the location, size and loading of each pane. AS 2208 covers safety glazing materials and applies where glass is in a location that presents a human impact risk, such as full-height glazing, doors, sidelights and low-level panels. Because safety glazing requirements depend on the specific application, the glazing schedule must identify which panes require safety glass rather than applying a blanket rule.

New Zealand: SNZ TS 4211:2022 and SNZ 4223

New Zealand projects are governed by the Building Code and by New Zealand standards and specifications for window performance and glazing. SNZ TS 4211:2022 is the technical specification applied to window performance in New Zealand, and SNZ 4223 addresses glazing practice. Together with the project’s consent documentation, they define how a window system is classified, tested and installed for New Zealand conditions, which differ from Australia in climate, wind and regulatory process. Meichen holds certification for 13 product lines under SNZ TS 4211:2022 and SNZ 4223, and for Australian projects it holds certification for 43 product series across the AS/NZS standards relevant to windows and doors, including AS 2047, AS 4284, AS 1288, AS 4666 and AS 2208. The company is actively pursuing CodeMark certification, the highest level of certification in Australia, and works with BV, CSI, NATA, AZUMA and INTERTEK for testing and verification.

Certification establishes that a system has been tested and assessed; it does not by itself guarantee that a particular project satisfies the NCC or the New Zealand Building Code. Compliance is always a project-level determination made by the relevant certifier, taking account of the specific size, configuration, wind load, climate zone and installation of each unit.

Energy Claims: Why They Must Stay Project-Specific

Window marketing is full of numbers, and most of them are true only in a context that the reader cannot see. A U-value quoted for a pane of glass is not the U-value of the whole window, because it excludes the frame, the spacer and the installation. A solar heat gain coefficient measured at normal incidence is not the same as the seasonal solar gain a real window experiences under real sun angles. A whole-house energy saving figure depends on the climate, the building’s geometry, the heating and cooling systems, the occupant behaviour and the baseline it is compared against. None of those can be transferred from one project to another.

For a passive-design project, the defensible approach is to specify performance requirements for the assembly, require test evidence for the specific system, and verify the result through the project’s energy model and, where relevant, post-completion testing. Claims about savings, comfort or acoustic benefit should be presented as project-specific outcomes to be verified, not as generic product attributes. Meichen publishes test-based performance for its systems, including water tightness under AS 4284, and its thermal and acoustic performance depends on the glazing build-up, frame system and installation of each project, all of which are confirmed in the project documentation.

Specifying a Passive-Design Package in Practice

A workable specification sequence follows the physics rather than the catalogue. First, fix the orientation and the shading strategy, because they determine what the glazing has to do. Second, set the glazing area for each façade and room based on daylight, view and thermal modelling. Third, select the glazing build-up, including coating, cavity and pane configuration, for each orientation. Fourth, select the frame system, using a thermally broken system where the thermal target requires it and confirming structural and water performance for the wind load. Fifth, detail the reveal, flashing and air barrier so the frame’s performance is not bypassed. Sixth, specify the installation standard and the inspection and recording regime. Seventh, commission the building and verify airtightness where the project targets require it.

Meichen’s role in that sequence is at steps three and four, and increasingly at step five, because the frame and reveal detail depends on the profile depth and fixing method. With 18 to 19 years of industry experience, a 20,000 sq m facility, aluminium sourced from AAG and glass from CSG, and hardware developed for Australian and New Zealand requirements, the company is set up to supply coordinated systems rather than isolated products. Its range covers ultra slim sliding and stacker doors, thermally broken sliding doors and awning, fixed, tilt and turn and double hung windows, no-mullion bi-fold doors, non-thermal-break systems, curtain walls in the BA150 series, and louvres, balustrades and shower enclosures for projects that need them.

Frequently Asked Questions

What is passive design in a window context?

Passive design means using the building’s form, orientation, shading, insulation, thermal mass and airtightness to manage comfort with minimal mechanical input. In a window context it means selecting orientation-specific glazing, providing shading that excludes summer sun and admits winter sun, using thermally broken frames, and installing the units so that the envelope is genuinely airtight.

Do passive-design projects always need triple glazing?

No. Triple glazing is most valuable in cold climates where winter heat loss dominates and where external noise is a concern. In milder or cooling-dominated climates, well-selected double glazing with appropriate Low-E coatings and good shading can be the better balance, particularly when the additional frame depth and weight of a triple-glazed unit would complicate the wall detail.

Can I mix different glazing types on the same house?

Yes, and on many passive-design projects you should. West-facing glass usually benefits from stronger solar control, north-facing glass from higher solar admission, and south-facing glass from a specification optimised for insulation. The glazing schedule should record the build-up for each orientation so that the correct unit is installed in the correct opening.

How is airtightness tested?

Airtightness is verified by a whole-building pressure test that measures airflow at a controlled pressure difference, often combined with a smoke or thermal-imaging survey to locate leaks. The test is carried out after the envelope is complete. For the window package, the critical preparatory step is inspecting and recording the perimeter seals before linings are installed.

Why does condensation form on new double-glazed windows?

Surface condensation on the room side means the internal glass or frame surface is below the dew point of the indoor air, which usually indicates high internal moisture, low ventilation, or a cold surface. Improving the thermal performance of the frame and glass raises the surface temperature, but moisture and ventilation must also be managed. Fogging inside the sealed cavity is different: it indicates a failed seal and the unit should be replaced.

What is the difference between AS 2047 and AS 4284?

AS 2047 is the product standard that sets out the performance characteristics windows and external glazed doors must satisfy. AS 4284 is a test method used to establish water penetration performance. A product is classified under AS 2047 on the basis of testing, and AS 4284 testing produces the water resistance result that supports that classification.

Is Meichen certified for Australian and New Zealand projects?

Yes. Meichen holds certification for 43 product series against the Australian standards relevant to windows and doors, including AS 2047, AS 4284, AS 1288, AS 4666 and AS 2208, and for 13 product lines under SNZ TS 4211:2022 and SNZ 4223 in New Zealand. The company is actively pursuing CodeMark certification. Individual project compliance is confirmed with the project’s certifier.

Conclusion

Passive design succeeds or fails at the envelope, and the window and door package is the most demanding part of that envelope. Orientation determines what the glass must do, shading determines how much sun reaches it, the glazing build-up and thermal break determine how much heat crosses it, airtightness determines how much air and moisture leak around it, ventilation determines how the building is refreshed without losing that control, and the frame, reveal and installation details determine whether any of it survives contact with a real wall. Each decision constrains the next, which is why the package should be resolved as a system early in design rather than assembled from a catalogue late in the process.

For Australian and New Zealand projects, that system also has to sit inside a compliance framework: the NCC and the ABCB for regulatory performance, AS 2047, AS 4284, AS 1288, AS 2208 and AS 4666 for products, testing, glass, safety glazing and installation, and SNZ TS 4211:2022 and SNZ 4223 for New Zealand. Certification supports compliance but does not replace project-level verification, and performance claims should always be framed as project-specific outcomes to be tested and confirmed. Meichen International Windows & Doors has built its Australian and New Zealand business since 2017 on that principle, combining thermally broken and ultra slim aluminium systems with double and triple Low-E glazing and test-backed water tightness of up to 960 Pa under AS 4284. To discuss a passive-design window and door package, visit mcwindow.com.au.