If you’ve been shopping for new windows lately, you’ve probably noticed those star-rating labels. They look a bit like the stickers on your fridge or washing machine. But what do they actually tell you about how a window will perform in your Perth home?

The Window Energy Rating Scheme (WERS) is a credible system that enables homeowners to understand window energy and overall energy performance. It provides a standardised way to compare different window products and their impact on whole-house energy efficiency.

The Window Energy Rating Scheme (WERS) is Australia’s way of helping you compare windows based on their energy performance. It’s managed by the Australian Fenestration Rating Council, and it gives every window a score from zero to ten stars.

For Perth homeowners, understanding these ratings can make a real difference to your energy costs, energy consumption, and comfort levels. WERS-rated windows also help reduce greenhouse gas emissions by improving energy efficiency across your home.

What Is the Window Energy Rating Scheme (WERS)?

WERS is a voluntary program, but it’s also recognised under the National Construction Code.

Think of it as a credible system that lets you compare different windows side by side. Instead of relying on vague marketing claims, you get standardised energy ratings based on actual performance testing. The scheme covers all window components, including frames, sashes, and glazing, to give a holistic view of energy efficiency.

Smart manufacturers offer WERS-rated windows because they know informed buyers want proof. The scheme measures whole window energy performance, not just the glass. That means that the window frame, window sashes, and every other window component get factored into the final WERS rating.

It’s a two-stage process involving computer simulation and, sometimes, physical testing to verify performance claims.

What Does the Window Energy Rating Tell You?

A WERS label shows several metrics, but three matter most for Perth homes.

• U-value (Uw): This tells you how well your window keeps heat in or out. The lower the number, the better the insulation your home has. Such windows with low U-values improve overall energy efficiency and reduce energy consumption for both heating and cooling.
• Solar Heat Gain Coefficient (SHGC or SHGCw): This indicates how much solar heat passes through your window. North-facing windows benefit from a moderate SHGC (around 0.30 to 0.45) to let in winter warmth, while east- and west-facing windows should have lower numbers to block harsh sun (0.30 or less).
• Visible Transmittance (Tvw): This measures natural light. Higher numbers mean more daylight, which reduces your need for artificial lighting during the day. Most high-quality windows sit between 0.4 and 0.7.

Why the Window Energy Rating Scheme Matters in Perth’s Climate

Most of Perth’s urban area sits in Climate Zone 5, which can be quite challenging. We get brutal summer heat, but winter mornings can drop to single digits. Your windows need to work both ways: keeping heat out when it’s 38 degrees, and keeping warm air inside when it’s 8 degrees.

WERS enables windows to be rated based on annual energy impact, helping homeowners make informed choices about reducing greenhouse gas emissions and energy consumption.

Data shows that up to 87% of summer heat gain comes through windows, with about 40% of heat loss in winter. That’s why the National Construction Code now requires new homes to meet a 7-star energy rating. Windows play a huge role in hitting that target. Obtaining energy ratings through WERS allows builders and homeowners to verify compliance with the NCC and demonstrate the performance of their window products.

The Real Benefits Beyond WERS

Energy ratings matter, but they’re not the whole story. When clients come to our Malaga showroom, they often mention comfort first, bills second. Better windows create more even temperatures throughout your home. No more cold spots near windows in winter or that oppressive radiant heat in summer.

Then, there’s also the financial side you need to consider. With electricity prices going up, investing in mid-range double-glazed windows now can pay for itself in around 6-8 years through lower energy costs. After that, you’re essentially saving money every year.

On top of that, having energy-efficient windows can make your home more attractive to buyers, which is important in Perth’s competitive property market. WERS-rated windows also improve home resale value by showing buyers the certified performance and sustainability of your home.

UV protection is another bonus. Low-E coatings block most ultraviolet rays, which means your furniture, carpets, and artwork won’t fade as quickly. And if you live near a busy road, double glazing significantly reduces outside noise.

How WERS Ratings Are Actually Created

Window makers submit their products to a rating organisation that is approved by the Australian Fenestration Rating Council (AFRC). The process starts with computer modelling software that simulates basic thermal behaviour. Engineers input every detail: glass specifications, the material of the window frames, seal types, spacer bars, and even the cavity width in double-glazed units.

For standard products, simulation is usually enough. But unusual or complex products might require physical testing in a lab to verify the computer predictions. All testing happens on a commercial-in-confidence basis, which protects manufacturers’ designs while ensuring the ratings are accurate. Energy raters then generate ratings that reflect both the heating and cooling performance for real windows in typical conditions.

Once approved, the window gets a tamper-proof label from the rating agency, showing its star rating and performance metrics. That label is your guarantee. If you need custom energy ratings for a non-standard size or configuration, they may arrange project-specific certificates.

It takes a bit longer, but it’s worth it for peace of mind, especially on large renovations. WERS enables windows to provide reliable information on energy consumption and performance of appliances, ensuring energy efficiency is maximised.

Choosing Windows That Help with Energy Efficiency

So, how do you actually pick the right windows? Start with the orientation.

• North-facing: These get consistent sun in winter. You want a decent SHGC (around 0.4) and good insulation (indicated by Uw below 3.5). This combination lets winter warmth in while keeping summer solar heat manageable.
• East and west: Harsh low-angle sun. Prioritise low SHGC (0.30 or less) so that less solar heat enters. Insulation still matters, but solar control is your main concern.
• South: Minimal direct sun. Focus entirely on insulation (aim for Uw below 3.0). SHGC is less critical here.

Additionally, the material of the window frames makes a big difference. Unplasticised Polyvinyl Chloride (uPVC) and composite frames naturally insulate better than aluminium. If you prefer the look of aluminium, make sure it’s thermally broken. That means there’s an insulating barrier inside the frame that stops heat transfer. Standard aluminium frames without this feature can’t achieve good U-values, no matter how fancy the glass is.

Finally, double glazing is becoming the norm for new builds and serious renovations. The gap between the two panes (usually 12 to 16 millimetres) acts as an insulator. If you add a Low-E coating to one glass surface, you’re looking at a significant upgrade in energy efficiency for both heating and cooling.

Meeting NCC Standards for Energy Efficiency

The National Construction Code sets minimum energy performance standards for new homes. As of 2022, most Class 1 buildings (that’s houses) need to achieve a 7-star rating in the Nationwide House Energy Rating Scheme (NatHERS). WERS-rated windows simplify the compliance process because the ratings feed directly into NatHERS calculations.

There’s also an alternative solution path if you’re doing something unconventional. This involves more detailed computer simulation and might require custom WERS certificates. We work with energy raters, so we understand what’s needed to keep projects moving.

For renovations, you’re not always bound by the same rules as new buildings. But upgrading to WERS-rated windows often makes sense anyway, especially if you’re planning to sell within five to ten years. The market increasingly values energy performance, and buyers notice the difference.

Transform Your Home with Perth Window and Door

Perth’s climate demands thoughtful window selection. Get it right, and you’ll enjoy lower energy costs, better comfort, reduced greenhouse gas emissions, and a more valuable property. Get it wrong, and you’re fighting a losing battle against the elements every summer and winter.

We can’t wait to help you find the perfect energy-efficient windows for your home. Book a free consultation where we’ll assess your specific needs and provide tailored recommendations. With WERS-rated windows and expert installation, you’re investing in comfort that lasts while reducing energy consumption and improving whole-house energy efficiency.