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Thermal performance is ingrained as a core concept of the AliClad suite with all designs optimised to improve energy efficiency and reduce thermal transfer whilst still maintaining a durable low maintenance exterior.

The Miglas AliClad suite can achieve U-values as low as 1.7, which coupled with exceptionally low air-infiltration provides a complete solution in the one suite.

In Australia, Energy Ratings are generalised by the Australian Window Association (AWA) with the Window Energy Rating Scheme (WERS). WERS rates windows with independent third-party simulations (and partly physical), to provide information as to how a well a window insulates, prevents solar heat gain, and how effective a window seals.

It is important to understand your design objectives when comparing WERS figures. A lower U-value and a lower Air Infiltration (AI) rating is always better, regardless of climate. Solar Heat Gain is dependent upon design principles and climate, in some applications a high solar heat gain is an objective to allow passive heating.

The window star ratings for heating and cooling rank the window against alternatives, using a scale based on 17 'generic' window types. The generic windows range from very low performance to very high performance in heating or cooling. The ratings apply to the effect of the whole window including the relative contributions of glass and frame.


WERS ratings provide a level comparison of different systems, but it is important to note in real-world applications the sizing will vary compared to the standardised tests and as a result, will change true figures. 


Important WERS Values

  1. The U-Value measures how well a product prevents heat from escaping a home/building in winter and entering it in summer. The lower the U-Value (Uw), the better the thermal efficiency product. U-Value (Uw) ratings generally fall between 2.00 and 2.95 for good quality double glazed products.

  2. Solar Heat Gain Coefficient (SHGC) measures how well a product blocks heat from the sun's rays. SHGC is expressed as a number between 0 and 1. The lower the SHGC, the better a product is at blocking unwanted heat gain.

  3. Visible Light Transmittance (VLT) measures how much light comes through a window. T is expressed as a number between 0 and 1. The higher the VLT, the greater the amount of daylight in your rooms. Everything over 0.25 is fine.

  4. Air Infiltration (AI) measures how much outside air comes into a home or building through a product. The lower the AI the better. With an AI of 0.07 Miglas provides the best performance of all WERS tested opening windows. AI of 0 is only achieved with fixed windows.

  5. Condensation Resistance (CR) measures how well a product resists the formation of condensation. CR is expressed as a number between 1 and 100. The higher the number, the better a product is able to resist condensation.

Certified Performance Data

In support of the rating labels, the window manufacturer can issue a certificate for that window type, spelling out in clear detail its energy performance

Certified Sticker

Certified Accreditation

You should also look for this label to certify that your window manufacturer is WERS accredited.


The labels ensure compliance with the WER Scheme, the BCA, and Australian Standard 2047.

WERS Accreditation Sticker

WERS Labels

The WERS sticker summarizes the values achieved. It shows the heating and cooling improvement as concise values with the specific data on the bottom. The concept of it is comparable to the rating you find on refrigerators. Sometimes the sticker is smaller or just the bottom part is used.

Thermal Window Simulation

≠ Not all U-Values are the same ≠

There are various ways that U-values are assessed globally, and it is important to ensure you are comparing apples with apples.


In Australia, derived from the NFRC (National Fenestration Rating Council [USA]), we test to "NFRC100" conditions, with a metric conversion. In Europe, The same value is produced under different conditions (CEN / ISO10077).


What does this mean? Surprisingly the NFRC100 conditions are 'harsher' with the temperature differentials almost double that of CEN / ISO10077. As a result, the U value figures vary in general by 10% 'better' for European produced values dependant upon frame material, but can also vary by up to 25% in some cases.

It is vital to ensure when looking at U-values, to make sure they are assessed to the Australian requirements of NFRC100 as per WERS.

Window Comparison and Evaluation

As a result of the WERS rating and the comparison with a standard aluminium frame single-glazed window, every product gets stars for heating improvement and cooling improvement.
Every additional star means you help the environment and you save money on your heating and cooling bills, all year round. All Miglas products get a minimum of 3.5 stars for cooling and heating. From this level, Miglas are able to match the requirements for your project and increase the star rating for cooling or heating depending on project demands.

The balance in both sections gives you comfort and energy savings all year round – not only when it is cold or hot.

How does Miglas rate?

WERS Chart

How do the ratings work?

Star Ratings

What do I save

Always look for a high and balanced rating for heating and cooling. That is the way to have comfort and savings all year round.

Ratings Chart
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