High Performance Windows for New Builds: What the Specification Requires

Specifying high performance windows for a new build is one of the most impactful decisions in the design and construction process. Windows are responsible for a disproportionate share of a home’s heat loss and heat gain relative to their area, and the performance of the window system determines whether a home achieves its energy rating, stays comfortable across Melbourne’s full climate range, and delivers the running cost savings that energy-efficient construction promises. This guide covers what high performance windows require technically and what Astellite offers for new build projects.

What High Performance Actually Means in a Window

The term high performance is used broadly in the window industry, and it is worth being specific about what it means technically. A genuinely high performance window system addresses thermal transmittance, solar heat gain, airtightness, and acoustic performance simultaneously, and each element is verified through independent testing rather than claimed by the manufacturer alone.

Thermal Transmittance

The U-value of the whole window system, including frame and glazing, measures how quickly heat transfers through the window from inside to outside. For new builds targeting 7 star NatHERS ratings or higher, U-values well below 2.0 W/m²K are typically required. Achieving this requires double or triple glazed units combined with uPVC frames of multi-chamber construction. Aluminium frames, even with thermal breaks, introduce thermal bridges that limit the achievable U-value of the system.

Solar Heat Gain

The solar heat gain coefficient determines how much solar radiation passes through the glass. For high performance windows in a new build, the SHGC needs to be managed by orientation. North-facing windows in Melbourne should allow useful winter solar gains while east and west-facing windows should limit summer overheating. This orientation-specific approach is part of the NatHERS modelling process and needs to be addressed in the window specification.

Airtightness

High performance new builds target low whole-building air leakage rates. Windows contribute to this through the sealing performance of the frame-to-opening junction and through the compression seal quality of the operating sash. Multi-point locking systems that engage at multiple points around the full frame perimeter are essential for achieving the low infiltration rates that high performance buildings require.

Independent Verification

High performance windows for a new build need to carry independently verified performance data. WERS ratings provide U-values, SHGC values, and air infiltration figures in a format that NatHERS assessors can use directly. Products without WERS certification cannot be modelled accurately in NatHERS and create compliance uncertainty for the project.

What Astellite Offers for High Performance New Builds

Astellite manufactures high performance windows for new builds using German-engineered Aluplast uPVC profiles and high-performance Lightbridge double and triple glazing. Products are WERS-rated and accredited by AGWA. Every unit is custom manufactured to the exact dimensions of the opening and installed by Astellite’s own team.

The full range includes tilt and turn windows, awning windows, sliding windows, bifold windows, fixed windows, bay windows, corner windows, and custom windows. Triple glazing is available across the range for passive house and near-passive applications. All products meet Australian building and safety standards and are backed by a 10-year warranty.

Astellite services new build projects in Melbourne, Geelong, Melton, and the Mornington Peninsula.