Conditioned façades
Operable openings where insulated glazing and thermally broken framing are required as part of the wider façade and H1 design.
Thermally Broken Glass Louvre System
BT90 Thermally Broken Glass Louvre System
A German-manufactured, centre-pivoting operable glass louvre system with thermally broken perimeter and blade framing for double-, triple- and selected single-glazed configurations.
BT90 uses individually framed horizontal glass blades within a 90 mm thermally broken perimeter frame. Each blade pivots through its centre, providing controlled ventilation while maintaining a framed insulated-glass appearance when closed.
The system uses a heavy-duty rack-and-pinion operating mechanism concealed within the side framing. It can be integrated with 24 V DC drives, window control panels, local switches, environmental sensors, BMS controls and project-specific ventilation sequences. Manual operation is also available for selected applications.
EBSA supports system selection, glass and façade coordination, performance evidence under SNZ TS 4211:2022, supply, installation options, automation, programming, commissioning and ongoing technical support.
System overview
Framed insulated-glass blades with centre-pivoting operation
BT90 is a commercial operable glass louvre in which each blade is contained within its own aluminium sash and pivots horizontally within a purpose-designed perimeter frame.
Thermal breaks are incorporated into both the perimeter frame and the individual blade holders. This provides a thermally separated pathway for façades requiring operable ventilation together with double- or triple-glazed glass.
The heavy-duty rack-and-pinion operating mechanism is concealed within the side framing, preserving a clean architectural appearance and allowing the blades to operate together as one coordinated opening.
- Centre-pivoting horizontally framed glass blades
- 90 mm thermally broken perimeter frame
- Thermally broken aluminium blade holders
- Double-, triple- and selected single-glazed configurations
- Concealed heavy-duty rack-and-pinion operating mechanism
- Electric or selected manual operating arrangements
Coordinate the blade holders with the project glazing
BT90 is normally selected where the project requires insulated glazing within an operable louvre system. The proposed glass should be coordinated with the blade holder, louvre dimensions, design pressures, glass weight, safety requirements and the wider façade glazing specification.
| BT90 configuration | Glazing accommodation | Typical application |
|---|---|---|
| BT90 IG32 | Double-glazed insulating glass units from 28–34 mm. | The standard BT90 pathway for H1 design, natural ventilation, mixed-mode ventilation and smoke-control applications. |
| BT90 IG44 | Triple-glazed insulating glass units from 40–44 mm. | Projects requiring a triple-glazed configuration, subject to glass weight and project-specific system assessment. |
| Selected single glazing | Single glazing from 9.52–12.76 mm within the IG32 blade holder. | Selected façade applications where a framed single-glazed blade is appropriate to the project design. |
| Frame finish | Anodised or powder-coated aluminium profiles. | Selected to coordinate with the surrounding façade and project finish specification. |
The final glass makeup is project-specific. Glass weight, pane makeup, safety treatment, coatings, edge conditions, dimensions, wind pressures and installation details are coordinated together with the nominal glass thickness.
Support the project’s H1 assessment with the selected configuration
The thermally broken frame and insulated-glass options make BT90 suitable for consideration within conditioned façades and other projects where thermal performance is important.
The project-specific thermal performance is calculated using the selected glass, overall louvre dimensions, frame-to-glass proportion, perimeter interfaces and installation arrangement.
BT90’s thermally broken framing and insulated-glass options can support the project’s H1 design. The selected louvre configuration should be included in the project thermal assessment to establish its contribution to the complete façade.
Tested under SNZ TS 4211:2022 using AS/NZS 4420.1 procedures
The current BT90 evidence is ift Rosenheim Test Report 26-001425-PR09, dated 23 June 2026. The testing was completed to SNZ TS 4211:2022, Specification for performance of windows, using the procedures in AS/NZS 4420.1:2016, Windows, external glazed, timber and composite doors — Methods of test — Part 1: Test sequence, sampling and test methods, including Amendment 1:2019.
The report records no deviations from the test method. The tested BT90 specimen measured 1500 mm wide × 2800 mm high.
The BT90 was tested to ±2500 Pa at serviceability limit state (SLS) and passed ultimate-strength testing at +6000 Pa and −4000 Pa at ultimate limit state (ULS).
The NZS 3604 wind-zone scale identifies Low, Medium, High, Very High and Extra High, with Extra High corresponding to a basic pressure of approximately 1.82 kPa. The BT90 SLS test pressure of 2.50 kPa is therefore above Extra High and falls within specific engineering design territory.
For specifically engineered projects, the calculated positive and negative SLS and ULS façade pressures can be compared directly with the corresponding tested pressures, together with the proposed louvre size, glass, support and installation arrangement.
Wind-load and deflection performance
| Performance measure | Tested pressure | NZ wind-zone classification | Recorded result |
|---|---|---|---|
| SLS — positive pressure | +2500 Pa |
Specific design — above Extra High Extra High corresponds to a basic pressure of approximately 1.82 kPa. |
Maximum deflection of 2.54 mm, equivalent to approximately L/558. |
| SLS — negative pressure | −2500 Pa |
Specific design — above Extra High Extra High corresponds to a basic pressure of approximately 1.82 kPa. |
Maximum deflection of 2.64 mm, equivalent to approximately L/537. |
| ULS — positive pressure | +6000 Pa | Specific engineering design | Passed. |
| ULS — negative pressure | −4000 Pa | Specific engineering design | Passed. |
The measured deflection was substantially better than the permitted limit. SNZ TS 4211:2022 limits deflection to span ÷ 250. For the tested span, this allowed approximately 5.7 mm of movement.
The BT90 moved only 2.54 mm under positive pressure and 2.64 mm under negative pressure — less than half the permitted movement.
The results are expressed as approximately L/558 and L/537, compared with the minimum requirement of L/250. In this measurement, the larger denominator is better: L/558 means less movement and greater stiffness than L/250.
Air and water performance
| Test | Test pressure | Recorded result |
|---|---|---|
| Air infiltration | +75 Pa | 0.61 L/s/m² |
| Air infiltration | −75 Pa | 0.65 L/s/m² |
| Air infiltration | +150 Pa | 0.99 L/s/m² |
| Air infiltration | −150 Pa | 1.02 L/s/m² |
| Water penetration resistance | 650 Pa for 15 minutes | No water penetration detected. |
Water-test results should be compared using the complete test method, not the pressure figure alone. The AS/NZS 4420 procedure used for this assessment applies continuous water while each nominated static pressure is maintained for 15 minutes. European test results may provide supplementary product information but use different procedures and are not directly interchangeable.
These results provide project teams with tested performance data for a 1500 mm wide × 2800 mm high BT90.
Where BT90 is typically considered
Mixed-mode ventilation
Automated natural ventilation coordinated with mechanical building services, temperature and carbon-dioxide sensors, weather inputs, operating schedules and BMS commands.
Education and civic buildings
Schools, universities, libraries, community buildings and other public facilities requiring robust operable façade openings and coordinated controls.
Smoke-control applications
Smoke relief, make-up air or natural smoke exhaust where the selected louvre, drive, control panel, wiring and interfaces are coordinated as part of the project fire-engineered design.
BT90 is particularly well suited to mixed-mode ventilation strategies and project-specific smoke-control applications because the louvres, drives, control panels, sensors and building interfaces can be coordinated as one operating system.
Automation and integration
Coordinate the louvres, drives and controls as one system
The normal automated BT90 arrangement uses a concealed 24 V DC drive. The drive operates the blades through the coordinated heavy-duty rack-and-pinion mechanism, while the blade system provides positive closing and locking as part of the complete assembly.
BT90 can be supplied with the D+H LDJ drive. The LDJ incorporates D+H ACB technology, allowing a compatible control system to provide real-time monitoring, fault and status reporting, remote programming and remote technical support, subject to the selected control-panel configuration and remote-connectivity arrangements.
EBSA can coordinate the complete system with local controls, environmental sensors, window control panels, BMS commands, mixed-mode ventilation logic and smoke-control operating sequences.
- D+H LDJ 24 V DC drive option
- ACB real-time actuator monitoring
- Fault and operating-status reporting
- Remote programming and technical support where configured
- Local open and close switches
- Room-temperature and carbon-dioxide sensors
- Rain and wind protection inputs
- Mixed-mode and night-ventilation strategies
- BMS enable, command and status interfaces
- Fire alarm and smoke-control interfaces where applicable
- Drive and control-panel programming
- Operational testing and commissioning
Resolve the complete opening before manufacture
BT90 is configured for the individual project. The louvre arrangement is coordinated with the façade, glazing, structure, controls and installation methodology before production information is released.
- Overall frame dimensions and operating arrangement
- Project design pressures and relevant test evidence
- Glass thickness, makeup, weight, coatings and safety treatment
- Supporting structure, frame fixings and construction tolerances
- Perimeter seals, flashings, drainage and adjacent façade interfaces
- Required opening angle, free area and ventilation performance
- Drive position, cable routes and control zones
- BMS, environmental sensor and fire-system interfaces
- Internal guarding or fall protection where required
- Cleaning, inspection and replacement access
Early coordination allows the project team to identify the relevant tested performance, confirm the glass and frame arrangement and resolve the structure, cabling and façade interfaces before manufacture.
Coordinate the louvre glass with the wider glazing package
BT90 can use suitable locally sourced glass. The glass may be supplied through the wider façade or glazing package, or supplied by EBSA as part of the agreed project scope.
Sourcing the louvre glass with the wider glazing package can help coordinate glass colour, coating, appearance and batch across the building. Where the glass is supplied by others, EBSA provides the required glass and blade-holder information and reviews the proposed arrangement within its agreed scope.
From product supply to a full turnkey solution
EBSA can be engaged by the builder, façade contractor, aluminium joiner, glazier, consultant or asset owner. The delivery model can be structured around the project team’s capability and preferred allocation of glazing, installation, controls and commissioning responsibilities.
| Delivery pathway | Typical EBSA role |
|---|---|
| Product supply | Supply of the project-configured BT90 louvre system with agreed product, installation and coordination information. |
| Supported façade delivery | Technical coordination with the builder, façade contractor, aluminium joiner or glazier on opening sizes, glass, support details, installation, drives and control requirements. |
| Supply and installation | Louvre supply and installation, including glazing where included in the agreed scope and using either EBSA-supplied glass or glass supplied through the wider project package. |
| Full turnkey solution | Design coordination, louvre supply, glass coordination, installation, field cabling, control panels, terminations, programming, commissioning, handover and ongoing support within the agreed scope. |
BT90 experience across education and civic façades
These completed Australian installations demonstrate BT90 within commercial, education and civic façades. They are included as product and application references for New Zealand project teams.
Shore School, Sydney
Framed BT90 operable glass louvres integrated into the building’s glazed external envelope.
Brisbane Girls Grammar School
BT90 openings incorporated into an education façade and coordinated natural-ventilation system.
Lady Huntingfield Childcare Centre, Melbourne
Thermally broken framed glass louvres coordinated with the architectural façade and ventilation requirements.
Allow time for coordination and German manufacture
BT90 systems are manufactured in Germany to the approved project configuration. The programme should allow for design coordination, glass confirmation, production information, approvals, manufacture, international freight, customs and local delivery.
- Confirm preliminary sizes and opening requirements
- Review the applicable SNZ TS 4211:2022 evidence
- Confirm project SLS and ULS design pressures and supporting structure
- Coordinate the glass makeup and supply responsibility
- Select the drive and control-panel configuration
- Define sensors, BMS, ACB and building interfaces
- Complete coordinated drawings and project approvals
- Allow for manufacture, freight, customs and local delivery
- Coordinate installation, glazing, cabling and commissioning access
German operable-louvre technology
Schneider Louvres technology supplied and supported by EBSA
BT90 is manufactured in Germany by Schneider Louvres. EBSA provides system selection, technical coordination, supply, automation, installation options, programming, commissioning and ongoing support for the system.
BT90 thermally broken operable glass louvre systems supplied and supported by EBSA.
BT90, MP2 or LF550?
| System | Glazing and operation | Typical selection reason |
|---|---|---|
| BT90 | Thermally broken, centre-pivoting framed double- or triple-glazed blades. | Insulated glazing within a clearly framed, thermally separated louvre system. |
| MP2 | Thermally broken, end-pivoting framed or structurally glazed insulated-glass blades. | Large insulated-glass blades with concealed operation and a framed or frameless external expression. |
| LF550 | Large-format point-fixed single-glazed, end-pivoting blades. | A lighter, highly transparent louvre construction where insulated glazing is not required. |
Compare BT90 with the wider glass louvre range
BT90 is the framed centre-pivoting option within EBSA’s operable glass louvre range. LF550 provides a large-format frameless single-glazed option, while MP2 SGI provides a thermally broken insulated-glass system with a structurally glazed external appearance.
Frequently asked questions
What makes the BT90 thermally broken?
Thermal breaks are incorporated into both the 90 mm perimeter frame and the individual aluminium blade holders. This reduces direct aluminium conduction through the louvre framing compared with a non-thermally broken system.
What glazing thicknesses can BT90 accept?
BT90 IG32 accepts double-glazed insulating glass units from 28–34 mm. BT90 IGU44 accepts triple-glazed units from 40–44 mm.
For selected applications, the IG32 blade holder can also accommodate single glazing from 9.52–12.76 mm.
Has BT90 been tested to New Zealand window performance standards?
Yes. A BT90 performance size of 1500 mm wide × 2800 mm high was tested against SNZ TS 4211:2022 using AS/NZS 4420.1:2016, including Amendment 1:2019.
How did BT90 perform in the SNZ TS 4211 deflection test?
SNZ TS 4211:2022 permitted approximately 5.7 mm of deflection for the tested span at ±2500 Pa. The measured deflection was only 2.54 mm under positive pressure and 2.64 mm under negative pressure.
These results equate to approximately L/558 and L/537, compared with the minimum pass level of L/250. The larger denominator indicates less movement, so L/558 represents substantially better stiffness than L/250.
What BT90 widths and heights are available?
BT90 dimensions are selected against the proposed glazing, glass weight, positive and negative design pressures, frame arrangement, fixing and supporting structure.
The current SNZ TS 4211:2022 performance size is 1500 mm wide × 2800 mm high.
EBSA can review other proposed dimensions and identify the relevant test evidence and project-specific assessment requirements.
What water-penetration result did BT90 achieve?
The 1500 mm wide × 2800 mm high BT90 tested against SNZ TS 4211:2022 achieved no water penetration at 650 Pa for 15 minutes.
How does BT90 support an H1 design?
BT90 combines thermally broken perimeter and blade framing with double- or triple-glazed blade options. The selected glass, louvre dimensions, frame proportion and installation arrangement can be included in the project thermal assessment to establish the completed system performance.
What does the D+H LDJ drive add to the BT90 system?
The D+H LDJ is a concealed 24 V DC drive developed for the BT90 operating mechanism. It can be supplied with D+H ACB technology for communication between the drive and a compatible control system.
Subject to the selected control-panel configuration and remote-connectivity arrangements, this can provide real-time monitoring, fault and status reporting, remote programming and remote technical support.
Is BT90 suitable for mixed-mode ventilation?
Yes. BT90 can form part of a mixed-mode ventilation strategy combining automated natural ventilation with mechanical building services.
The louvres can be controlled using temperature, carbon-dioxide, rain and wind sensors, operating schedules, local controls and BMS commands, subject to the agreed control strategy.
Can BT90 glass be supplied locally?
Yes. Suitable locally sourced glass can be used, provided the proposed thickness, makeup, weight, safety treatment, coatings, edge conditions and compatibility with the BT90 blade holder are confirmed.
Can BT90 be manually operated?
Yes. Manual operation is available for selected applications. Electric operation is normally preferred where the louvres form part of an automated natural ventilation, BMS or smoke-control system.
Can BT90 form part of a smoke-control system?
Yes, where the selected BT90 arrangement, drive, controls, wiring and interfaces are coordinated with the project fire-engineered design.
EBSA can assist with the louvre, automation and control-system scope and coordinate the required operating sequence with the relevant project consultants.
What finishes are available?
BT90 aluminium profiles can be anodised or powder coated to coordinate with the surrounding façade. Finish availability, colour, coating specification and lead time are confirmed before manufacture.
What access should be allowed for maintenance?
Projects should provide safe access for inspection, cleaning, drainage checks, operational testing, drive adjustment and future glass or drive replacement. Maintenance access is best resolved during façade coordination.
When should EBSA become involved?
Early design development provides the best opportunity to coordinate the louvre dimensions, glass, project pressures, supporting structure, test evidence, drives, controls, approvals and German manufacturing programme.
Discuss a BT90 glass louvre project with EBSA
Contact EBSA to discuss BT90 system selection, evidence under SNZ TS 4211:2022, glazing, wind-load performance, mixed-mode ventilation, smoke control, automation, installation, commissioning or procurement timing.
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