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

Awning Window

Sliding Window

Fixed Window

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 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.

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.

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

Better

Best

Excellent

Internal Ventilation

Ventilation openings are often needed in internal walls.

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.

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 1, 2 & 3

Hot Summers & Mild/Warm Winters

OBJECTIVES

Maximise cooling natural ventilation with Altair Louvre Windows.
Reduce solar heat gain on East, West and South orientations by using toned glazing, glazing with low e coatings, or aluminium louvre blades. Increase solar heat gain on Northern orientation.
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 4 & 5

Hot Summers & Cool Winters

OBJECTIVES

Maximise cooling natural ventilation with Altair Louvre Windows.
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).
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 Zones 6, 7 & 8

Warm/Hot Summers & Cool/Cold Winters

OBJECTIVES

Maximise cooling natural ventilation with Altair Louvre Windows.
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).
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 Type	WERS Windows ID	WERS Glazing Code	WERS Heating Stars⁹	Uw⁶	SHGC⁷	Tvw⁸
Easyscreen Louvre Single Glaze¹
6mm SolTech Neutral	BRZ-006-11	6SolT Ntl		4.5	0.41	0.48
6mm thick clear glass	BRZ-006-01	6Clr		6.2	0.64	0.68
6mm thick grey tinted glass	BRZ-006-07	6Gy		6.2	0.51	0.49
6mm thick bronze tinted glass	BRZ-006-02	6Bz		6.2	0.48	0.39
6mm thick green tinted glass	BRZ-006-06	6Gn		6.2	0.46	0.57
6mm thick super green tinted glass	BRZ-006-05	6SG		6.2	0.4	0.5
6mm thick clear low E glass²	BRZ-006-08	6LE		4.4	0.47	0.66
6mm thick E-Vantage clear glass²	BRZ-006-03	6EVan		4.8	0.48	0.5
6mm thick E-Vantage grey tinted glass²	BRZ-006-04	6EVanGy		4.8	0.32	0.21
Easyscreen Louvre Single Glazed - Crimsafe Security Screen ³
6mm thick clear glass	BRZ-990-01	6Clr		4.6	0.3	0.27
6mm thick grey tinted glass	BRZ-990-07	6Gy		4.6	0.24	0.13
6mm thick bronze tinted glass	BRZ-990-02	6Brz		4.6	0.25	0.15
6mm thick green tinted glass	BRZ-990-06	6Gn		4.6	0.25	0.23
6mm thick super green tinted glass	BRZ-990-05	6SpGn		4.6	0.23	0.2
6mm thick clear low E glass²	BRZ-990-08	6ET		3.6	0.25	0.25
6mm thick E-Vantage clear glass²	BRZ-990-03	6EVClr		3.7	0.23	0.21
6mm thick E-Vantage grey tinted glass²	BRZ-990-04	6EVGrey		3.7	0.2	0.1
Easyscreen Louvre Single Glazed - Invisigard Security Screen³
6mm thick clear glass	BRZ-991-01	6Clr		4.5	0.31	0.28
6mm thick grey tinted glass	BRZ-991-07	6Gy		4.5	0.26	0.13
6mm thick bronze tinted glass	BRZ-991-02	6Brz		4.5	0.27	0.16
6mm thick green tinted glass	BRZ-991-06	6Gn		4.5	0.26	0.24
6mm thick super green tinted glass	BRZ-991-05	6SpGn		4.5	0.25	0.21
6mm thick clear low E glass²	BRZ-991-08	6ET		3.6	0.26	0.26
6mm thick E-Vantage clear glass²	BRZ-991-03	6EVClr		3.7	0.25	0.22
6mm thick E-Vantage grey tinted glass²	BRZ-991-04	6EVGrey		3.7	0.21	0.1
Easyscreen Louvre Single Glazed - Prowler Proof ForceField Security Screen ³
6mm thick clear glass	BRZ-992-01	6Clr		4.5	0.31	0.28
6mm thick grey tinted glass	BRZ-992-07	6Gy		4.5	0.25	0.13
6mm thick bronze tinted glass	BRZ-992-02	6Brz		4.5	0.26	0.16
6mm thick green tinted glass	BRZ-992-06	6Gn		4.5	0.26	0.24
6mm thick super green tinted glass	BRZ-992-05	6SpGn		4.5	0.24	0.21
6mm thick clear low E glass²	BRZ-992-08	6ET		3.6	0.26	0.26
6mm thick E-Vantage clear glass²	BRZ-992-03	6EVClr		3.7	0.24	0.22
6mm thick E-Vantage grey tinted glass²	BRZ-992-04	6EVGrey		3.7	0.20	0.10
Easyscreen Fixed Lite Single Glazed¹
6mm thick clear glass	BRZ-007-01	6Clr		6.2	0.72	0.76
6mm thick grey tinted glass	BRZ-007-07	6Gy		6.2	0.56	0.55
6mm thick bronze tinted glass	BRZ-007-02	6Bz		6.2	0.53	0.43
6mm thick green tinted glass	BRZ-007-06	6Gn		6.2	0.51	0.64
6mm thick super green tinted glass	BRZ-007-05	6SG		6.2	0.44	0.56
6mm thick clear low E glass²	BRZ-007-08	6LE		4.1	0.53	0.74
6mm thick E-Vantage clear glass²	BRZ-007-03	6EVan		4.5	0.53	0.56
6mm thick E-Vantage grey tinted glass²	BRZ-007-04	6EVanGy		4.5	0.35	0.27
SL2 Louvre Single Glazed¹
6mm thick clear glass	BRZ-003-01	6Clr		6	0.72	0.52
6mm thick grey tinted glass	BRZ-003-02	6Gy		6	0.5	0.26
6mm thick super grey tinted glass	BRZ-003-06	6SpGy		6	0.31	0.05
6mm thick bronze tinted glass	BRZ-003-03	6Bz		6	0.54	0.32
6mm thick evergreen tinted glass	BRZ-003-04	6EG		6	0.46	0.39
6mm thick arctic blue tinted glass	BRZ-003-05	6AB		6	0.46	0.33
6mm thick clear low E glass²	BRZ-003-13	6LE		4.1	0.62	0.48
Innoscreen Louvre Single Glazed¹
6mm thick clear glass	BRZ-009-01	6Clr		6.9	0.63	0.63
6mm thick grey tinted glass	BRZ-009-02	6Gy	N/A	6.9	0.50	0.46
6mm thick green tinted glass	BRZ-009-08	6Gn	N/A	6.9	0.45	0.54
6mm thick ever green tinted glass	BRZ-009-09	6EG	N/A	6.9	0.40	0.47
6mm thick E-Vantage clear glass²	BRZ-009-04	6EVanClr		5.7	0.48	0.48
6mm thick E-Vantage grey glass²	BRZ-009-10	6EVanGy		5.7	0.32	0.23
6mm thick EnergyTech clear glass²	BRZ-009-03	6ET		5.5	0.53	0.58
6mm thick EnergyTech grey glass²	BRZ-009-07	6ETGy		5.6	0.37	0.28
6mm thick SolTech Neutral glass²	BRZ-009-05	6SolTNtl		5.6	0.41	0.45
6mm thick Sunergy glass²	BRZ-009-06	6Sn		5.8	0.46	0.48
Innoscreen Fixed Lite Single Glazed¹
6mm thick clear glass	BRZ-008-01	6Clr		6.3	0.73	0.76
6mm thick grey tinted glass	BRZ-008-02	6Gy		6.3	0.58	0.55
6mm thick green tinted glass	BRZ-008-08	6Gn		6.3	0.52	0.64
6mm thick ever green tinted glass	BRZ-008-09	6EG		6.3	0.46	0.56
6mm thick E-Vantage clear glass²	BRZ-008-04	6EVanClr		4.7	0.55	0.58
6mm thick E-Vantage grey glass²	BRZ-008-10	6EVanGy		4.7	0.36	0.27
6mm thick EnergyTech clear glass²	BRZ-008-03	6ET		4.5	0.61	0.69
6mm thick EnergyTech grey glass²	BRZ-008-07	6ETGy		4.6	0.41	0.34
6mm thick SolTech Neutral glass²	BRZ-008-05	6SolTNtl		4.5	0.47	0.54
6mm thick Sunergy glass²	BRZ-008-06	6Sn		4.9	0.52	0.58
Altair Louvre Components in Timber Frame Single Glazed¹
6mm thick clear glass	BRZ-005-01	6Clr		4.9	0.58	0.62
6mm thick grey tinted glass	BRZ-005-02	6Gy		4.9	0.41	0.29
6mm thick super grey tinted glass	BRZ-005-06	6SoGy		4.9	0.25	0.06
6mm thick bronze tinted glass	BRZ-005-03	6Bz		4.9	0.44	0.34
6mm thick evergreen tinted glass	BRZ-005-04	6EG		4.9	0.37	0.47
6mm thick arctic blue tinted glass	BRZ-005-05	6AB		4.9	0.37	0.37
6mm thick clear low E glass²	BRZ-005-13	6LE		3.4	0.49	0.57
6mm thick Sunergy glass²	BRZ-005-14	6Sn		3.7	0.42	0.48
Dualair Louvre in Alspec Hunter EVO 150mm Acoustic Frame Secondary Glazed¹¹
6mm Clear / 101mm Air Gap / 6mm Clear	BRZ-010-01	6Clr/101/6Clr		3.8	0.46	0.48
6mm LowE (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-010-02	6LE/101/6Clr		3.2	0.15	0.14
6mm LowE (#2)¹⁰ / 101mm Air Gap / 6mm LowE (#2)¹⁰	BRZ-010-03	6LE/101/6LE		2.9	0.11	0.05
6mm EnergyTech (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-010-04	6ET/101/6Clr		3.4	0.40	0.44
6mm EVantage Clear (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-010-05	6EVanClr/101/6Clr		3.4	0.37	0.38
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		3.4	0.47	0.49
6mm LowE (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-011-02	6LE/101/6Clr		2.8	0.14	0.14
6mm LowE (#2)¹⁰ / 101mm Air Gap / 6mm LowE (#2)¹⁰	BRZ-011-03	6LE/101/6LE		2.4	0.10	0.05
6mm EnergyTech (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-011-04	6ET/101/6Clr		3.0	0.40	0.45
6mm EVantage Clear (#2)¹⁰ / 101mm Air Gap / 6mm Clear	BRZ-011-05	6EVClr/101/6Clr		3.0	0.37	0.39
IGLU Louvre Components in Timber Frame Double Glazed
5mm Planibel G (#2)¹⁰ / 12mm Argon / 5mm Planibel G (#3)¹⁰	BZW-012-01	5PbG/12Ar/5PbG		2.6	0.4	0.43
Easyscreen IGLU Louvre Double Glazed
5mm Planibel G (#2)¹⁰ / 12mm Argon / 5mm Planibel G (#3)¹⁰	BZW-014-01	5PbG/12Ar/5PbG		3.6	0.41	0.44
Easyscreen IGU Fixed Lite Double Glazed
4mm Clear / 10mm Argon Gap / 4mm Clear	BRZ-015-01	4Clr/10Ar/4Clr		3.4	0.64	0.68
4mm Clear / 10mm Argon Gap / 4mm EnergyTech (#3)¹⁰	BRZ-015-02	4Clr/10Ar/4ET		2.7	0.60	0.63
4mm EnergyTech (#2)¹⁰ / 10mm Argon Gap / 4mm EnergyTech (#3)¹⁰	BRZ-015-03	4ET/10Ar/4ET		2.6	0.52	0.58
4mm Clear / 10mm Argon Gap / 4mm Sunergy (#3)¹⁰	BRZ-015-04	4Clr/10Ar/4Sn		2.9	0.57	0.52
5mm Clear / 8mm Argon Gap / 5mm Clear	BRZ-015-05	5Clr/8Ar/5Clr		3.5	0.61	0.66
5mm Clear / 8mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-06	5Clr/8Ar/5ET		2.8	0.57	0.61
5mm EnergyTech (#2)¹⁰ / 8mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-07	5ET/8Ar/5ET		2.7	0.51	0.57
4mm Clear / 12mm Argon Gap / 4mm Clear	BRZ-015-08	4Clr/12Ar/4Clr		3.4	0.64	0.67
4mm Clear / 12mm Argon Gap / 4mm EnergyTech (#3)¹⁰	BRZ-015-09	4Clr/12Ar/4ET		2.6	0.60	0.63
4mm EnergyTech (#2)¹⁰ / 12mm Argon Gap / 4mm EnergyTech (#3)¹⁰	BRZ-015-10	4ET/12Ar/4ET		2.5	0.52	0.58
4mm Clear / 12mm Argon Gap / 4mm Sunergy (#3)¹⁰	BRZ-015-11	4Clr/12Ar/4Sn		2.8	0.58	0.52
5mm Clear / 10mm Argon Gap / 5mm Clear	BRZ-015-12	5Clr/10Ar/5Clr		3.4	0.61	0.66
5mm Clear / 10mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-13	5Clr/10Ar/5ET		2.7	0.57	0.61
5mm EnergyTech (#2)¹⁰ / 10mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-14	5ET/10Ar/5ET		2.6	0.51	0.57
6mm Clear / 8mm Argon Gap / 6mm Clear	BRZ-015-15	6Clr/8Ar/6Clr		3.5	0.60	0.66
6mm Clear / 8mm Argon Gap / 6mm EnergyTech (#3)¹⁰	BRZ-015-16	6Clr/8Ar/6ET		2.8	0.57	0.61
6mm EnergyTech (#2)¹⁰ / 8mm Argon Gap / 6mm EnergyTech (#3)¹⁰	BRZ-015-17	6ET/8Ar/6ET		2.7	0.50	0.56
6mm Clear / 8mm Argon Gap / 6mm EVantage (#3)¹⁰	BRZ-015-18	6Clr/8Ar/6EV		2.9	0.51	0.52
6mm Clear / 8mm Argon Gap / 6mm Sunergy (#3)¹⁰	BRZ-015-19	6Clr/8Ar/6Sn		3.0	0.55	0.51
5mm Clear / 14mm Argon Gap / 5mm Clear	BRZ-015-20	5Clr/14Ar/5Clr		3.3	0.61	0.66
5mm Clear / 14mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-21	5Clr/14Ar/5ET		2.6	0.58	0.61
5mm EnergyTech (#2)¹⁰ / 14mm Argon Gap / 5mm EnergyTech (#3)¹⁰	BRZ-015-22	5ET/14Ar/5ET		2.5	0.51	0.57
6mm Clear / 12mm Argon Gap / 6mm Clear	BRZ-015-23	6Clr/12Ar/6Clr		3.3	0.60	0.66
6mm Clear / 12mm Argon Gap / 6mm EnergyTech (#3)¹⁰	BRZ-015-24	6Clr/12Ar/6ET		2.6	0.57	0.61
6mm EnergyTech (#2)¹⁰ / 12mm Argon Gap / 6mm EnergyTech (#3)¹⁰	BRZ-015-25	6ET/12Ar/6ET		2.5	0.50	0.57
6mm Clear / 12mm Argon Gap / 6mm EVantage (#3)¹⁰	BRZ-015-26	6Clr/12Ar/6EV		2.7	0.52	0.52
6mm Clear / 12mm Argon Gap / 6mm Sunergy (#3)¹⁰	BRZ-015-27	6Clr/12Ar/6Sn		2.8	0.55	0.51

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)

Energy Ratings of Obscure Glass Blades

Blade Type	Uw	SHGC	Tvw
Breezway Easyscreen Altair Louvre Window System - Single Glazed⁴
6mm thick hollow extruded aluminium⁵	6.55	0.076	0

Notes:

Results disclosed at Australian Fenestration Rating Council (AFRC) regulations.
These blades have a microscopically thin low emissivity coating that is invisible to the naked eye and improves insulation and reduces solar heat gain.
Results disclosed in Standard International Units. Results calculated to the procedures of WERS Screen Rating Methodology, 2012.
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.
As the optical properties of aluminium are not contained in the International Glazing Databse (IGDB), known, default properties were used.
Uw is the whole window U-value.
SHGCw is the whole windows solar heat gain co-efficient.
Tvw is the whole window visible (light) transmittance.
Star ratings calculated using Nationwide House Energy Rating Software (AccuRate) according to procedures of WERS 2008.
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.
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.

Window Energy Efficiency

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.

Maximum Ventilation

Solar Control

Sealing

Insulation

Cross Flow Ventilation

Internal Ventilation

Thermal Chimney Effect

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 1, 2 & 3

Climate Zone 4 & 5

Climate Zones 6, 7 & 8

Energy Efficiency

Ventilation Rates & Energy Efficiency

Natural Ventilation in Offices Case Study

WERS Ratings

BREEZWAY LOUVRES

Benefits of energy efficiency

Downloads

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.