Meeting the new 7 Star Energy Rating requirements with windows

Staying well-informed with industry requirements for design and construction projects can be challenging for specifiers. ArchiPro speaks with aluplast, a global window system manufacturer and supplier, about the effect windows have on thermal efficiency and the benefits of uPVC windows.

Established four decades ago in Germany, family-owned aluplast designs and produces window systems with suppliers Australia-wide. “With a global business turnover of around 750 million euros annually, we are in more than 100 countries assisting specifiers and homeowners," says Ben Webster, Managing Director of aluplast.

The new minimum 7 Star Energy Rating (NatHERS) applies to all new Australian homes as adopted by all states and territories in May 2023. Although several states have further delayed some requirements, the updated energy efficiency provisions are now in effect in New South Wales and Victoria. According to Webster, the concern about meeting the new NatHERS requirements can be alleviated with thermal windows. 

“uPVC windows have a much higher energy rating, making it a lot easier to meet seven-star standards. The projects our systems are being utilised on are sometimes reaching 8.5 to even 10-star energy ratings. So, with our high-performance systems you can meet standards now and well into the future.”

Webster further explains, "uPVC frames have a low rate of conduction. This means the transference of hot or cold through the profile is greatly reduced. And that's one of the main differences."

Aluplast recently worked with ESD consultants EcoResults to demonstrate how to add 1.5 stars or more to a new home build. EcoResults simulated the impact of using standard double-glazed aluminium windows versus aluplast double-glazed uPVC-framed windows with upgraded underfloor, internal wall, and roof insulation on a development of 10 townhouses.

The results showed that using standard double-glazed aluminium windows, the average NatHERS rating was modest at 5.8 stars. However, when switched to aluplast double-glazed uPVC-framed windows, the rating increased to 1 and 1.3 stars across the ten townhouses, with an average rating of just under the new 7-star requirements. 

After combining the aluplast uPVC windows along with R2.5 underfloor and internal wall insulation and a slight upgrade in roof insulation (from R4.0 to R5.0), the average rating increased to 7.5 stars. 

“This improvement highlights the significant energy efficiency gains achievable with the right materials, particularly windows,” says Webster.

This finding confirms that upgrading windows and insulation is the most direct and effective strategy to enhance a home's energy performance.

Located in Victoria's southwest, Tower Hill House is a model for sustainable progress. Designed by architect and certified Passivhaus designer Fiona Golding, Tower Hill House captures stunning views across the lake formed within an extinct volcano crater and out towards Port Fairy. 

The project brief was to create a home that is exemplary in comfort and sustainability and takes full advantage of expansive views and radiant northern sunlight. The layout cleverly divides the structure into two separate entities—the main dwelling and an upper-floor guest apartment over the garage—each subtly angled to maximise views while ensuring privacy.

The home's materiality included recycled timber posts, rendered hempcrete, bluestone and timber board and batten. Made from hemp fibre and lime, hempcrete is naturally fire- and pest-resistant, forming walls and insulation in one piece.

The dwelling's design achieved high thermal efficiency with an impressive 8.3-star energy rating, significantly above the then-minimum requirement of 6 stars. Integrating the hempcrete walls with Aluplast's DEAL 4000 uPVC windows and doors manufactured by Thermosmart was pivotal. Golding explains, "Given the high performance of the hempcrete walls, it was imperative to pair them with windows and doors of equal calibre." She notes that the decision to opt for triple glazing provided a substantial performance upgrade for less than an additional 10 per cent cost.

Golding says the owners' preference for uPVC for the window and door system was influenced by its widespread use and proven performance in Europe. "The clients chose uPVC for its high performance, durability, low maintenance, and value," says Golding. The clients opted for aluplast’s Turner Oak Malt frames, which have a timber-like appearance that complements the home's organic palette.

Golding remarks, "Large windows were crucial for making the most of the site's extraordinary views, necessitating high-performance windows to deliver on both the views and energy efficiency."

Tower Hill House’s self-contained guest apartment benefits from the triple glazing system's acoustic privacy and separation, an aspect Golding considers essential for multi-use dwellings.

"While it has taken a while for some clients to come on board, the tide is changing as they discover uPVC's performance, durability and lower maintenance needs," says Golding.

Compliance and beyond

While most of the market wants to tick a box, aluplast sees the Seven Star Energy Rating as a minimum baseline we should try to exceed.

"Slowly but surely, the drive to reduce carbon and energy consumption is going to grow step by step with each code change, and our products will meet and exceed it for years to come,” says Webster. “We’re confident that if you put our product in today, it will still meet the Australian requirements in 10 years' time.”

To learn more or for a supplier list, contact aluplast on ArchiPro today.