WERS Rating Explained: Window Energy Ratings in Adelaide

What is a WERS rating?

A WERS rating is a window energy rating from the Window Energy Rating Scheme, run by the Australian Window Association. It rates a whole window, frame and glass together, with separate star ratings for heating and cooling. For Adelaide homeowners, it is a useful way to compare energy efficient windows on published figures rather than marketing claims.

Window brochures are full of words like “thermal”, “high performance” and “energy saving”. A WERS rating cuts through that by putting tested numbers on the whole window. This guide explains what the stars and figures mean, which ones matter most in Adelaide’s climate, and how to use them when you compare quotes. It is general information: Clearfox Windows isn’t a rating body, and where a product we quote carries published WERS figures, we pass them on with the quote.

How the Window Energy Rating Scheme works

WERS is Australia’s own scheme for rating the energy performance of windows and skylights. Rather than rating the glass on its own, it rates the complete window as it would be installed: frame, glass, seals and spacers together.

Each rated window gets:

• A heating star rating, showing how well the window helps keep a home warm in winter.
• A cooling star rating, showing how well it helps keep a home cool in summer.
• The underlying performance figures, mainly the whole-window U-value and solar heat gain coefficient.

The star ratings run from 0 to 10, and more stars means better performance for that season. A window can rate well for heating and only moderately for cooling, or the other way round, depending on its glass and frame.

U-value: how well the window insulates

The whole-window U-value (Uw) measures how readily heat flows through the window because of a temperature difference between inside and outside.

• Lower U-value = better insulation.
• It matters on cold winter nights, when heat inside is escaping, and on hot days, when outside heat is conducting in.
• Double glazing, Low-E coatings, gas fills and thermally broken or non-metal frames all lower the U-value.

Because it is a whole-window figure, the frame counts. A good glass unit in a frame that conducts heat freely ends up with a higher U-value than the glass alone would suggest. That is one reason thermally broken aluminium windows and uPVC frames perform better on paper.

SHGC: how much solar heat gets through

The solar heat gain coefficient (SHGC) measures how much of the sun’s heat striking the window ends up inside the home. It is a number between 0 and 1.

• Lower SHGC = less solar heat comes through.
• Higher SHGC = more solar heat comes through, which can be welcome in winter on north-facing glass.

In Adelaide, SHGC is often the figure that matters most on west-facing windows, where hot afternoon sun can overheat living areas. A lower SHGC there helps keep rooms cooler. On north-facing glass with good eaves, a moderate SHGC can let in welcome winter sun while the eaves block high summer sun.

Which WERS figures matter most in Adelaide

Adelaide has hot, dry summers and cool, wet winters, so both heating and cooling performance count. A sensible way to use the figures is by orientation:

Orientation	What to look for
West	Lower SHGC and a good cooling star rating to cut afternoon heat
North	Balance: good U-value, moderate SHGC if eaves shade summer sun
East	Good U-value; moderate SHGC to limit morning heat in summer
South	Low U-value and a good heating star rating, as little direct sun reaches it

For colder Adelaide Hills homes, heating performance and U-value carry more weight. For western and northern suburbs living areas with big west-facing glass, cooling performance and SHGC usually matter most. Our guide to Low-E glass for Adelaide’s climate explains how glass coatings shift those figures.

How WERS relates to new homes in South Australia

New homes in South Australia must meet the NCC 2022 energy-efficiency provisions, adopted in SA from 1 October 2024. That includes a minimum 7-star NatHERS rating and a Whole of Home assessment. Window performance figures, such as the U-value and SHGC published through WERS, feed into that energy assessment.

In practice, your energy assessor works out what performance the windows need, and your builder or window supplier provides windows with figures that meet it. If you are building, ask your assessor for the window U-value and SHGC targets before you price windows. Our new build windows page explains how we quote from drawings.

Reading a window energy rating label or data sheet

When you compare windows, look for:

1. The product and configuration the figures apply to: frame system, window style and glass build-up.
2. Whole-window U-value (Uw), not just a glass-only “centre of glass” figure, which will look better.
3. Whole-window SHGC.
4. Heating and cooling star ratings, if shown.
5. Visible light transmittance, if you care about keeping rooms bright; some heavily tinted glass cuts light as well as heat.

Make sure two quotes are comparing the same thing. A sliding window and a fixed window in the same frame system will have different figures, and so will clear double glazing and Low-E double glazing.

Common misunderstandings

• “Double glazed” doesn’t mean a specific rating. Two double-glazed windows can have very different U-values and SHGCs.
• Glass-only figures flatter the window. Ask for whole-window figures.
• More stars isn’t always the right choice. A window with a very high heating rating may let in more solar heat than you want on a west wall.
• Not every window is WERS-rated. Some products publish performance data in other ways; ask how the figures were obtained.

Related services

Clearfox Windows supplies and installs energy-efficient windows, double glazing and new build windows across Adelaide metro and the Adelaide Hills. Where the products we quote carry published WERS figures, we pass them on so you can compare. For a wider view, see our guide to energy-efficient windows, BAL ratings and U-values.

Frequently asked questions

What does WERS stand for?

WERS stands for the Window Energy Rating Scheme, Australia’s scheme for rating the energy performance of windows and skylights. It is run by the Australian Window Association and rates the whole window, frame and glass together.

What is a good U-value for windows in Adelaide?

Lower is better, but the right target depends on the room, the orientation and, for new homes, your energy assessment. Compare whole-window U-values between products, and for new builds ask your energy assessor what the design needs.

What is the difference between U-value and SHGC?

U-value measures how readily heat conducts through the window because of a temperature difference. SHGC measures how much of the sun’s heat striking the window gets inside. In Adelaide, both matter, with SHGC especially important on west-facing glass.

Are WERS ratings required in South Australia?

New homes must meet the NCC 2022 energy-efficiency provisions, adopted in SA from 1 October 2024, and window performance feeds into that assessment. Published WERS figures are a common way to show window performance, and your energy assessor or builder confirms what is needed.

Is Clearfox Windows WERS certified?

We aren’t a rating body and don’t certify windows. Where the products we quote carry published WERS ratings or performance figures, we pass them on with the quote so you can compare like with like.

How many WERS stars should my windows have?

There is no single right number. Look at heating and cooling ratings separately and match them to the orientation: cooling performance matters most on west-facing glass in Adelaide, and heating performance matters most on south-facing glass and in the Hills.

Get an energy-efficient windows quote

Want published figures you can compare? Request a quote or call 0468 038 136. We’ll get back to you within 24–48 hours, measure on site for free, and give you a written, itemised quote listing the glass and frame for every window.