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Window Energy Efficiency

Natural ventilation

Altair® Louvre Windows provide energy-efficient control of natural light and fresh air in a building. Increasing natural ventilation can improve the health and productivity of building occupants whilst reducing the reliance on air conditioning.

By adjusting the angle of the Breezway Louvre Blades, inhabitants can regulate the amount of air that enters their living space, while simultaneously maximising their views of the surrounding landscape. View project.

Maximum Ventilation

Altair Louvres are considered to be the most energy-efficient window on the market, due to their unique ability to provide close to 100% ventilation, which sets them apart from other window systems.

Altair Louvre Window

Altair Louvre Window

Awning Window
Awning Window
Sliding Window
Sliding Window
Fixed Window
Fixed Window
Breezway tinted green louvre blades

Solar Control

Controlling the amount of heat entering a home from the sun is important for comfort and energy efficiency. Clear windows let in a lot of heat, but tinted windows can reduce this heat gain. In hot climates and on western-facing windows, a low solar heat gain coefficient (SHGC) is desirable. In colder climates and on northern-facing windows, a higher SHGC is desirable.

Altair Louvre Windows:

  • Have a Solar Heat Gain Coefficient (SHGC) between 0.1 and 0.72 using glass blades and tinted low-e glass.
  • Block out sunlight and allow ventilation with timber or aluminum louvre blades.
  • Prevent Solar Heat Gain by angling blades while maintaining ventilation.
  • Reduce Solar Heat Gain with metal mesh screens that are WERS rated.
Breezway Living Hinge

Sealing

Altair Louvre Windows provide tight sealing significantly better than the standard required for residential windows due to:

  • A living hinge design that prevents water and air penetration.
  • An over-center locking mechanism for strong closure.
  • Double-glazed IGLU blades with rubber seals for superior sealing.
Breezway IGLU Insulation

Insulation

U-values measure a window’s thermal conductivity, or how quickly heat transfers through it. Lower U-values mean slow heat transfer and higher U-values indicate fast transfer. The importance of U-values depends on the outdoor temperature difference.

Altair Louvre Windows have U-values ranging from 2.4 to 6.9 (see table below) and can outperform some double-glazed windows when using low e coatings.

Note: In extremely cold climates, louvre/fixed/louvre combination windows are a good way to achieve good ventilation and very low U-values.

Cross Flow Ventilation

The importance of window placement.

Good

Good

Better

Better

best

Best

Excellent

Excellent

Internal Ventilation

Ventilation openings are often needed in internal walls.

Internal ventilation

The drawing above illustrates how a ventilation adjustable louvre window between rooms is more efficient than just having external louvre windows alone.

Thermal Chimney Effect

Installing windows up high.

Breezway Thermal Chimney Effect
Another good way to naturally cool a room is to place some Altair Powerlouvre Windows up high. This is effective because rising hot air is able to escape the room through the high up louvres, helping to keep the room cool.

Australian Climate Zones

There are a variety of Altair Louvre Window design principles that can achieve a comfortable indoor climate, save energy used for heating and cooling and meet the energy efficiency requirements of the National Construction Code.

Climate Zone 123

Climate Zone 1, 2 & 3

Hot Summers & Mild/Warm Winters

OBJECTIVES

  1. Maximise cooling natural ventilation with Altair Louvre Windows.
  2. Reduce solar heat gain on East, West and South orientations by using toned glazing, glazing with low e coatings, timber or aluminium louvre blades. Increase solar heat gain on Northern orientation.
  3. Reduce conducted heat gain by using windows with lower U-values.

Read the Guide To Ideal Altair Louvre Windows in Climate Zones 1, 2 & 3

Climate Zone 45

Climate Zone 4 & 5

Hot Summers & Cool Winters

OBJECTIVES

  1. Maximise cooling natural ventilation with Altair Louvre Windows.
  2. Reduce solar heat gain on East, West and South orientations. Increase beneficial solar heat gain on Northern orientation (i.e. Northern windows should have clear glazing to allow high SHGC and shading that allows solar exposure in winter).
  3. Reduce conducted heat gain and loss by using windows with lower U-values.

Read the Guide To Ideal Altair Louvre Windows in Climate Zones 4 & 5

Climate Zone 678

Climate Zones 6, 7 & 8

Warm/Hot Summers & Cool/Cold Winters

OBJECTIVES

  1. Maximise cooling natural ventilation with Altair Louvre Windows.
  2. Increase solar heat gain on Northern orientation. Reduce solar heat gain on East, West and South orientations (Adding or enlarging Northern windows can improve a home’s energy rating).
  3. Reduce conducted heat loss by using windows with lower U-values.

Read the Guide To Ideal Altair Louvre Windows in Climate Zones 6, 7 & 8

Energy Efficiency

Altair Louvre Windows by Breezway are an energy efficient way to control natural light and fresh air into your home or office environment.

The video explains the benefits of Altair Louvre Windows that maximise natural ventilation as well as sealing tightly.

Ventilation Rates & Energy Efficiency

Ventilation is essential to create a naturally comfortable home. This short video compares the ventilation rates of different window types.

Natural Ventilation in Offices Case Study

The new Breezway Head Office displays a spectacular showcase of Breezway Altair Louvre Windows, in particular the Altair Powerlouvre Window that has been integrated into a building management system to achieve a cost efficient, environmentally sustainable commercial building design.

WERS Ratings

For mobile devices: Use your finger to scroll table horizontally.

Altair Louvres meet U-value requirements for energy efficiency in all climate zones.

WERS Certified Products Directory – AFRC
Residential ratings available here.
Commercial ratings available here.

Blade TypeWERS Windows IDWERS Glazing CodeWERS Cooling Stars9WERS Heating Stars9Uw6SHGC7Tvw8

Easyscreen Louvre Single Glaze1

6mm SolTech NeutralBRZ-006-116SolT Ntl4.50.410.48
6mm thick clear glassBRZ-006-016Clr6.20.640.68
6mm thick grey tinted glassBRZ-006-076Gy6.20.510.49
6mm thick bronze tinted glassBRZ-006-026Bz6.20.480.39
6mm thick green tinted glassBRZ-006-066Gn6.20.460.57
6mm thick super green tinted glassBRZ-006-056SG6.20.40.5
6mm thick clear low E glass2BRZ-006-086LE4.40.470.66
6mm thick E-Vantage clear glass2BRZ-006-036EVan4.80.480.5
6mm thick E-Vantage grey tinted glass2BRZ-006-046EVanGy4.80.320.21

Easyscreen Louvre Single Glazed - Crimsafe Security Screen 3

6mm thick clear glassBRZ-990-016Clr4.60.30.27
6mm thick grey tinted glassBRZ-990-076Gy4.60.240.13
6mm thick bronze tinted glassBRZ-990-026Brz4.60.250.15
6mm thick green tinted glassBRZ-990-066Gn4.60.250.23
6mm thick super green tinted glassBRZ-990-056SpGn4.60.230.2
6mm thick clear low E glass2BRZ-990-086ET3.60.250.25
6mm thick E-Vantage clear glass2BRZ-990-036EVClr3.70.230.21
6mm thick E-Vantage grey tinted glass2BRZ-990-046EVGrey3.70.20.1

Easyscreen Louvre Single Glazed - Invisigard Security Screen3

6mm thick clear glassBRZ-991-016Clr4.50.310.28
6mm thick grey tinted glassBRZ-991-076Gy4.50.260.13
6mm thick bronze tinted glassBRZ-991-026Brz4.50.270.16
6mm thick green tinted glassBRZ-991-066Gn4.50.260.24
6mm thick super green tinted glassBRZ-991-056SpGn4.50.250.21
6mm thick clear low E glass2BRZ-991-086ET3.60.260.26
6mm thick E-Vantage clear glass2BRZ-991-036EVClr3.70.250.22
6mm thick E-Vantage grey tinted glass2BRZ-991-046EVGrey3.70.210.1

Easyscreen Louvre Single Glazed - Prowler Proof ForceField Security Screen 3

6mm thick clear glassBRZ-992-016Clr4.50.310.28
6mm thick grey tinted glassBRZ-992-076Gy4.50.250.13
6mm thick bronze tinted glassBRZ-992-026Brz4.50.260.16
6mm thick green tinted glassBRZ-992-066Gn4.50.260.24
6mm thick super green tinted glassBRZ-992-056SpGn4.50.240.21
6mm thick clear low E glass2BRZ-992-086ET3.60.260.26
6mm thick E-Vantage clear glass2BRZ-992-036EVClr3.70.240.22
6mm thick E-Vantage grey tinted glass2BRZ-992-046EVGrey3.70.200.10

Easyscreen Fixed Lite Single Glazed1

6mm thick clear glassBRZ-007-016Clr6.20.720.76
6mm thick grey tinted glassBRZ-007-076Gy6.20.560.55
6mm thick bronze tinted glassBRZ-007-026Bz6.20.530.43
6mm thick green tinted glassBRZ-007-066Gn6.20.510.64
6mm thick super green tinted glassBRZ-007-056SG6.20.440.56
6mm thick clear low E glass2BRZ-007-086LE4.10.530.74
6mm thick E-Vantage clear glass2BRZ-007-036EVan4.50.530.56
6mm thick E-Vantage grey tinted glass2BRZ-007-046EVanGy4.50.350.27

SL2 Louvre Single Glazed1

6mm thick clear glassBRZ-003-016Clr60.720.52
6mm thick grey tinted glassBRZ-003-026Gy60.50.26
6mm thick super grey tinted glassBRZ-003-066SpGy60.310.05
6mm thick bronze tinted glassBRZ-003-036Bz60.540.32
6mm thick evergreen tinted glassBRZ-003-046EG60.460.39
6mm thick arctic blue tinted glassBRZ-003-056AB60.460.33
6mm thick clear low E glass2BRZ-003-136LE4.10.620.48

Innoscreen Louvre Single Glazed1

6mm thick clear glassBRZ-009-016Clr6.90.630.63
6mm thick grey tinted glassBRZ-009-026GyN/A6.90.500.46
6mm thick green tinted glassBRZ-009-086GnN/A6.90.450.54
6mm thick ever green tinted glassBRZ-009-096EGN/A6.90.400.47
6mm thick E-Vantage clear glass2BRZ-009-046EVanClr5.70.480.48
6mm thick E-Vantage grey glass2BRZ-009-106EVanGy5.70.320.23
6mm thick EnergyTech clear glass2BRZ-009-036ET5.50.530.58
6mm thick EnergyTech grey glass2BRZ-009-076ETGy5.60.370.28
6mm thick SolTech Neutral glass2BRZ-009-056SolTNtl5.60.410.45
6mm thick Sunergy glass2BRZ-009-066Sn5.80.460.48

Innoscreen Fixed Lite Single Glazed1

6mm thick clear glassBRZ-008-016Clr6.30.730.76
6mm thick grey tinted glassBRZ-008-026Gy6.30.580.55
6mm thick green tinted glassBRZ-008-086Gn6.30.520.64
6mm thick ever green tinted glassBRZ-008-096EG6.30.460.56
6mm thick E-Vantage clear glass2BRZ-008-046EVanClr4.70.550.58
6mm thick E-Vantage grey glass2BRZ-008-106EVanGy4.70.360.27
6mm thick EnergyTech clear glass2BRZ-008-036ET4.50.610.69
6mm thick EnergyTech grey glass2BRZ-008-076ETGy4.60.410.34
6mm thick SolTech Neutral glass2BRZ-008-056SolTNtl4.50.470.54
6mm thick Sunergy glass2BRZ-008-066Sn4.90.520.58

Altair Louvre Components in Timber Frame Single Glazed1

6mm thick clear glassBRZ-005-016Clr4.90.580.62
6mm thick grey tinted glassBRZ-005-026Gy4.90.410.29
6mm thick super grey tinted glassBRZ-005-066SoGy4.90.250.06
6mm thick bronze tinted glassBRZ-005-036Bz4.90.440.34
6mm thick evergreen tinted glassBRZ-005-046EG4.90.370.47
6mm thick arctic blue tinted glassBRZ-005-056AB4.90.370.37
6mm thick clear low E glass2BRZ-005-136LE3.40.490.57
6mm thick Sunergy glass2BRZ-005-146Sn3.70.420.48

Dualair Louvre in Alspec Hunter EVO 150mm Acoustic Frame Secondary Glazed11

6mm Clear / 101mm Air Gap / 6mm Clear
BRZ-010-01
6Clr/101/6Clr
3.80.460.48
6mm LowE (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-010-02
6LE/101/6Clr
3.20.150.14
6mm LowE (#2)10 / 101mm Air Gap / 6mm LowE (#2)10
BRZ-010-03
6LE/101/6LE
2.90.110.05
6mm EnergyTech (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-010-04
6ET/101/6Clr
3.40.400.44
6mm EVantage Clear (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-010-05
6EVanClr/101/6Clr
3.40.370.38

Dualair Louvre in Alspec McArthur EVO 150mm Centre Pocket Frame Secondary Glazed11

6mm Clear / 101mm Air Gap / 6mm Clear
BRZ-011-01
6Clr/101/6Clr
3.40.470.49
6mm LowE (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-011-02
6LE/101/6Clr
2.80.140.14
6mm LowE (#2)10 / 101mm Air Gap / 6mm LowE (#2)10
BRZ-011-03
6LE/101/6LE
2.40.100.05
6mm EnergyTech (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-011-04
6ET/101/6Clr
3.00.400.45
6mm EVantage Clear (#2)10 / 101mm Air Gap / 6mm Clear
BRZ-011-05
6EVClr/101/6Clr
3.00.370.39

IGLU Louvre Components in Timber Frame Double Glazed

5mm Planibel G (#2)10 / 12mm Argon / 5mm Planibel G (#3)10BZW-012-01 5PbG/12Ar/5PbG2.60.40.43

Easyscreen IGLU Louvre Double Glazed

5mm Planibel G (#2)10 / 12mm Argon / 5mm Planibel G (#3)10BZW-014-01 5PbG/12Ar/5PbG3.60.410.44

Easyscreen IGU Fixed Lite Double Glazed

4mm Clear / 10mm Argon Gap / 4mm ClearBRZ-015-014Clr/10Ar/4Clr3.40.640.68
4mm Clear / 10mm Argon Gap / 4mm EnergyTech (#3)10BRZ-015-024Clr/10Ar/4ET2.70.600.63
4mm EnergyTech (#2)10 / 10mm Argon Gap / 4mm EnergyTech (#3)10BRZ-015-034ET/10Ar/4ET2.60.520.58
4mm Clear / 10mm Argon Gap / 4mm Sunergy (#3)10BRZ-015-044Clr/10Ar/4Sn2.90.570.52
5mm Clear / 8mm Argon Gap / 5mm ClearBRZ-015-055Clr/8Ar/5Clr3.50.610.66
5mm Clear / 8mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-065Clr/8Ar/5ET2.80.570.61
5mm EnergyTech (#2)10 / 8mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-075ET/8Ar/5ET2.70.510.57
4mm Clear / 12mm Argon Gap / 4mm ClearBRZ-015-084Clr/12Ar/4Clr3.40.640.67
4mm Clear / 12mm Argon Gap / 4mm EnergyTech (#3)10BRZ-015-094Clr/12Ar/4ET2.60.600.63
4mm EnergyTech (#2)10 / 12mm Argon Gap / 4mm EnergyTech (#3)10BRZ-015-104ET/12Ar/4ET2.50.520.58
4mm Clear / 12mm Argon Gap / 4mm Sunergy (#3)10BRZ-015-114Clr/12Ar/4Sn2.80.580.52
5mm Clear / 10mm Argon Gap / 5mm ClearBRZ-015-125Clr/10Ar/5Clr3.40.610.66
5mm Clear / 10mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-135Clr/10Ar/5ET2.70.570.61
5mm EnergyTech (#2)10 / 10mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-145ET/10Ar/5ET2.60.510.57
6mm Clear / 8mm Argon Gap / 6mm ClearBRZ-015-156Clr/8Ar/6Clr3.50.600.66
6mm Clear / 8mm Argon Gap / 6mm EnergyTech (#3)10BRZ-015-166Clr/8Ar/6ET2.80.570.61
6mm EnergyTech (#2)10 / 8mm Argon Gap / 6mm EnergyTech (#3)10BRZ-015-176ET/8Ar/6ET2.70.500.56
6mm Clear / 8mm Argon Gap / 6mm EVantage (#3)10BRZ-015-186Clr/8Ar/6EV2.90.510.52
6mm Clear / 8mm Argon Gap / 6mm Sunergy (#3)10BRZ-015-196Clr/8Ar/6Sn3.00.550.51
5mm Clear / 14mm Argon Gap / 5mm ClearBRZ-015-205Clr/14Ar/5Clr3.30.610.66
5mm Clear / 14mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-215Clr/14Ar/5ET2.60.580.61
5mm EnergyTech (#2)10 / 14mm Argon Gap / 5mm EnergyTech (#3)10BRZ-015-225ET/14Ar/5ET2.50.510.57
6mm Clear / 12mm Argon Gap / 6mm ClearBRZ-015-236Clr/12Ar/6Clr3.30.600.66
6mm Clear / 12mm Argon Gap / 6mm EnergyTech (#3)10BRZ-015-246Clr/12Ar/6ET2.60.570.61
6mm EnergyTech (#2)10 / 12mm Argon Gap / 6mm EnergyTech (#3)10BRZ-015-256ET/12Ar/6ET2.50.500.57
6mm Clear / 12mm Argon Gap / 6mm EVantage (#3)10BRZ-015-266Clr/12Ar/6EV2.70.520.52
6mm Clear / 12mm Argon Gap / 6mm Sunergy (#3)10BRZ-015-276Clr/12Ar/6Sn2.80.550.51
Ratings by co-principal developer of WERS Dr Peter Lyons
Based on WERS calculation methodology but beyond current AFRC procedures (not available at https://www.awawers.net, only available at www.breezway.com.au)

Blade TypeUwSHGCTvw

Breezway Easyscreen Altair Louvre Window System - Single Glazed4

14mm thick Western Red Cedar timber 54.390.0950
6mm thick hollow extruded aluminium56.550.0760
Notes:

  1. Results disclosed at Australian Fenestration Rating Council (AFRC) regulations.
  2. These blades have a microscopically thin low emissivity coating that is invisible to the naked eye and improves insulation and reduces solar heat gain.
  3. Results disclosed in Standard International Units. Results calculated to the procedures of WERS Screen Rating Methodology, 2012.
  4. These ratings are not authorised WERS ratings and should be regarded as a research report, they have been generated using the WERS calculation methodology but are beyond current AFRC procedures. Calculated performance indices are suitable for comparison with information on the WERS database.
  5. As the optical properties of cedar timber and aluminium are not contained in the International Glazing Databse (IGDB), known, default properties were used.
  6. Uw is the whole window U-value.
  7. SHGCw is the whole windows solar heat gain co-efficient.
  8. Tvw is the whole window visible (light) transmittance.
  9. Star ratings calculated using Nationwide House Energy Rating Software (AccuRate) according to procedures of WERS 2008.
  10. Numeric values next to Low E glasses e.g. (#2) and (#3) refer to the coated surface of the glazing layer. Secondary glazing figures are treated as two individual glass layers with two surfaces each. Double glazed figures are treated as a single unit with four surfaces. Surfaces counted externally to internally.
  11. The glazing is reported in the same orientation as it is simulated so that the outside is always on the left, inside is always on the right.

Static Performance (Uw SHGCw Tvw Tdw) calculated using Window 6.3 and Therm 6.3 software (LBNL), 1999-2010.

BREEZWAY LOUVRES

Benefits of energy efficiency

To learn more about the benefits of energy efficiency, Breezway has produced a number of Technical Bulletins to assist with your building designs.