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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

Compliance with Clause H1

As stated by the New Zealand Building Code (NZBC), “Buildings must be constructed to achieve an adequate degree of energy efficiency when energy is used for modifying temperature or humidity, or both;..”

The NZBC Clause H1 offers a variety of compliance options to which Altair Louvre Windows can meet the mimimum energy requirements. For example:

  • Using the Schedule Method – Altair Louvre Windows can be used with a low e coating in a timber frame.
  • Using the Calculation or Modelling Method – Any Altair Louvre can be used provided other building elements compensate.

Altair Louvres also offer other benefits that are not measured in the energy ratings, including:

  • Health benefits of ventilation
  • Ability to precisely control ventilation
  • Stylish aesthetics
  • Customising opportunities
Breezway Living Hinge


In winter, the last thing that you want is windows that don’t seal tight and let in cold draughts. Altair Louvre Windows provide tight sealing due to:

  • A living hinge design that prevents water and air penetration.
  • An over-center locking mechanism for strong closure.
NZ Climate Zone Map

New Zealand Climate Zones

There are a variety of good Altair Louvre Window design principles that can achieve a comfortable indoor climate and save energy used for heating and cooling across all New Zealand climate zones.

Consider installing a number of clear windows in the northern orientation of the home with low window system R-values (this can be achieved through framing or low e glazing). By incorporating Altair Louvre Windows next to fixed lite panels, a beautiful view can be framed while still gaining natural ventilation to improve the indoor air quality and reduce the build-up of mould or condensation.

Climate Zone 1
Auckland, North
Climate Zone 2
Balance North Island, except Central Plateau
Climate Zone 3
South Island & Central Plateau

Cross Flow Ventilation

The importance of window placement.









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.

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 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
View Residential ratings.
View Commercial ratings.

Blade TypeWERS Windows IDWERS Glazing CodeWERS Cooling Stars6WERS Heating Stars6Uw3SHGC4Tvw5

Breezway Altair Louvre Components in a timber frame - Single Glazed1

Breezway Altair Louvre Components in a 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

Breezway Altair IGLU Louvre Components in a Timber Frame – Double Glazed

5mm Planibel G (#2)10 / 12mm Argon / 5mm Planibel G (#3)10BZW-012-015PbG/12Ar/5PbG2.60.40.43

  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. Uw is the whole window U-value.
  4. SHGCw is the whole windows solar heat gain co-efficient.
  5. Tvw is the whole window visible (light) transmittance.
  6. Star ratings calculated using Nationwide House Energy Rating Software (AccuRate) according to procedures of WERS 2008.

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


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.