A guide to energy ratings

Window energy ratings: what builders and energy raters need to know.

This quick, easy-to-follow guide outlines some basic information around energy efficiency compliance requirements for windows.

Learn about the ratings systems for product performance and how you can avoid lost time or money due to inaccurate or non-compliant energy reports.

The background

At A&L, we take compliance, standards, and regulation seriously.

We work hard to ensure our products offer the highest quality, comfort, and performance.

As part of that, we’re committed to creating simple guidelines to help builders and energy raters quickly understand nationally-regulated technical benchmarks relating to those categories; how A&L products measure up against those standards; and what you need to do when recording or reporting A&L product performance in energy reports.

Learn what to do as a builder
Learn what to do as an energy rater

You can also read on to understand a basic overview of energy efficiency reporting requirements, terms, and conventions.

Understanding the general requirements

Energy efficiency performance requirements are outlined in accordance with various sections of the National Construction Code, which is maintained by the Australian Building Codes Board (ABCB) on behalf of the Australian Government and each State and Territory Government.

The National Construction Code has provisions that relate to energy efficiency for all classes of buildings. It may also contain State and Territory-specific variations to those requirements, to accommodate differences in climate and various other factors which can impact product performance.

Regardless of your location or the style of your building, energy reports must meet the requirements of the National Construction Code to be compliant.

There are a range of performance-based simulation tools—including AccuRate, FirstRate, BERS PRO and BASIX—which are commonly used to gauge compliance and generate energy reports. It is worth noting that recent changes to these software platforms mean accurate product information is more important than ever before.

For window products, energy reports must specify performance using two main values:

  1. SHGC values: Solar Heat Gain Coefficient (SHGC) values indicate how well a window product blocks heat caused by sunlight. A product’s SHGC value is expressed as a decimal number between 0 and 1; the lower a window’s SHGC value, the less solar heat it transmits.
  2. U values: The U value measures how well a window product prevents heat from passing through. The lower the U value, the greater a window’s resistance to heat flow, and therefore the better its insulating value.

These values—along with other product performance information—are recorded in an industry database referred to as the Window Energy Rating Scheme (commonly referred to as WERS). WERS codes are typically used in the creation of energy reports.

Frequently used A&L WERS codes

The importance of product-specific WERS codes

There are two varieties of WERS codes:

  1. Generic WERS codes: these codes are neither product nor supplier specific, and as a result, may not be as accurate as their product-specific counterparts. Using generic WERS codes may result in non-compliant energy reports, and as a result, costly upgrades.
  2. Product-specific WERS codes: Created by independent, certified laboratories from design data provided by the product manufacturers, these codes offer highly specific SHGC and U values based on a product’s exact materials and specifications for frame, glazing, and other components. Although they are typically more accurate, product-specific WERS codes can only be accessed by an energy rater who has completed an additional Australian Window Association online accreditation course.

Product-specific WERS codes ensure builders receive the best possible price from suppliers, as well as greater assurance of compliance with energy efficiency regulations as mandated by the National Construction Code.

What to do as a builder

To ensure you get an accurate energy report, compliant window products, and the cheapest possible price for your windows, you should:

  1. Ensure your energy rater is NatHERS accredited (certificates from non-accredited raters are not valid in many states) and in addition has completed the AWA qualification to be able to use custom (manufacturer specific) ratings. This means the energy rater will be able to access A&L product-specific WERS codes and provide highly specified energy reports based on the exact materials and product components used in the building(s), rather than using generic—and potentially less accurate or non-compliant—product and performance information.
  2. When you are using A&L products in your homes, ensure that all energy raters—and therefore the energy reports they create—use A&L product-specific WERS codes.
  3. Ensure that all products ordered match the product-specific codes used in the energy report. For example, if an energy report is completed with one supplier’s specific codes and then similar windows are ordered through a different supplier, this will not be compliant.

What to do as an energy rater

  1. Complete the Australian Window Association‘s online training course, if you have not already, which provides access to A&L product-specific WERS codes.
  2. Ensure you use A&L product-specific WERS codes when creating any future energy reports.
  3. If required, familiarise yourself with the recent changes to tolerance leeway for performance-based simulation tools. These changes require that any windows supplied remain within 5% of the listed SHGC value when generic codes are used on the energy report, which when combined with minimum U value requirements, is either impossible to meet or can result in costly product upgrades for your customer.

***Disclaimer: This article contains information that is correct at the time of publication but may be subject to change by other parties. It should not be viewed as a definitive guide and should be read in conjunction with the National Construction Code and any relevant state and territory regulations.