Both matter.

A high-performing glass unit can still lose effectiveness when fitted into a poorly insulated frame. Likewise, a thermally broken frame will not reach its potential when paired with unsuitable glazing.

Window performance should therefore be assessed as a complete system that includes:

• The glass
• The frame
• The spacer between the panes
• Opening sections
• Seals and gaskets
• The installation around the window

New Zealand’s Window Energy Efficiency Rating System also assesses the combination of glass and frame rather than treating them separately.

Brass can be used in coastal environments, but the level of exposure needs to be considered carefully.

Salt carried through the air may settle on the frames, fittings and glass. This can accelerate surface changes and increase cleaning requirements, particularly on exposed sites close to the water.

For coastal projects, it is worth discussing:

• • Distance from the shoreline
  • Prevailing wind direction
  • Frame and hardware specifications
  • Recommended protective finishes
  • Cleaning frequency
  • Access for maintenance

A sheltered coastal property will have different requirements from a home directly exposed to sea spray.

Insulated glazing commonly uses two or more panes of glass separated by a sealed space.

The gap between the panes helps slow heat transfer. Depending on the specification, it may contain dry air or an insulating gas such as argon. Low-emissivity glass coatings can also be used to reduce radiant heat transfer.

A typical system may include:

• Double or triple glazing
• A sealed air or gas-filled cavity
• A warm-edge spacer
• Low-emissivity glass
• Laminated or toughened panes where required

The correct glass specification will depend on the building’s location, orientation, window size and required thermal, acoustic and safety performance.

Most new homes and additions in New Zealand require double glazing to meet Building Code requirements. Appropriate glazing and frame selection can reduce heat loss and improve comfort.

R-values and U-values describe thermal performance in different ways.

R-value measures resistance to heat flow. A higher R-value generally means better insulation.

U-value measures how readily heat passes through a building element. A lower U-value generally indicates better thermal performance.

It is important to confirm whether a quoted figure applies to:

• The glass alone
• The centre of the glazing unit
• The frame
• The complete window

A glass-only figure does not represent the performance of the entire installed system.

New Zealand Building Code Clause H1 addresses the energy efficiency of the wider building envelope, which includes windows and doors. The current H1 compliance documents use calculation and modelling pathways rather than relying on one standard window specification for every project.

They can help, but no window system can guarantee that condensation will never occur.

Condensation develops when warm, moisture-laden indoor air meets a surface that is cold enough for water vapour to form droplets.

A thermal break can keep the internal frame surface warmer, while insulated glazing can raise the temperature of the inside glass pane. Together, these features reduce the likelihood of the window becoming the coldest surface in the room.

Condensation also depends on:

• Indoor humidity
• Heating
• Ventilation
• Outdoor temperature
• Curtains and blinds
• Building insulation
• How the room is used

MBIE advises that improving the thermal performance of both the glazing and frame, while keeping the home warm and well ventilated, is the most effective approach to reducing window condensation.

Triple glazing can improve insulation, but it is not automatically the best option for every project.

Additional panes make the glazing unit thicker and heavier. This may affect frame selection, hardware, opening sizes and cost.

Triple glazing may be worth considering for:

• Colder parts of New Zealand
• Highly exposed sites
• Large glazed areas
• Projects with demanding energy targets
• Rooms where acoustic performance is important

In milder conditions, a well-designed thermally broken frame with high-quality double glazing may provide the right balance of comfort, weight and cost.

The decision should be based on the performance of the whole building rather than the number of glass panes alone.

Good insulation does not prevent a room from overheating when too much direct sunlight passes through the glass.

Solar heat gain describes how much heat from the sun enters through a window. It can be useful during winter, but excessive solar gain may make north and west-facing rooms uncomfortable during warmer months.

The glass specification may need to balance:

• Winter heat retention
• Useful solar warmth
• Summer overheating
• Natural light
• Glare
• Views
• Exterior shading

BRANZ recommends considering the solar heat gain coefficient when selecting glazing, particularly as overheating becomes a growing concern in New Zealand homes.

Yes. A well-specified window can still underperform if gaps around the frame allow uncontrolled air movement.

Installation details should address:

• Insulation around the opening
• Air sealing
• Weather sealing
• Flashings and drainage
• Frame alignment
• Junctions with the surrounding wall
• Compatibility with cladding and interior linings

Even small gaps can allow air movement and reduce the effectiveness of insulation around a building element.

The right specification should consider the frame and glazing together.

Before selecting a brass window system, discuss:

• The local climate
• Window size and orientation
• Required R-value or U-value
• Double or triple glazing
• Low-emissivity coatings
• Solar heat gain
• Condensation risk
• Acoustic and safety requirements
• Opening style
• Building Code compliance

2K supplies thermally broken brass window systems for residential and commercial projects across New Zealand. Speak with the team about the glazing, frame profile and performance requirements for your project.