Understanding Energy Efficient Window Terms

When it comes to choosing windows for your home or project, understanding the technical terms can be quite challenging, especially when energy efficiency is involved!

In this article, we’ll explain some common window terms and their relationship to energy efficient windows, making it easier for you to make informed decisions. 

What are U-values?

U-values, or thermal transmittance, measure the rate at which heat passes through a material. In window terms, U-values indicate the amount of heat loss or gain through the glass. When looking at U-values, lower numbers are what you’re after– lower U-values signify better insulation and greater energy efficiency.

Here’s a breakdown of U-values for different types of windows:

• Single glazed windows: These have the highest U-values among all window types. With only one pane of glass, they offer minimal insulation, which means a lot of heat escapes. Typically, U-values for single glazed windows range from 4.0 to 6.0.
• Double glazed windows: This type of window consists of two panes of glass separated by a spacer filled with air or gas. This provides much better insulation compared to single glazed windows, which leads to lower U-values. You’ll generally see U-values for double glazed windows ranging from 1.2 to 3.0.

Opting for windows with lower U-values helps in reducing energy consumption, enhancing comfort, and minimising heating and cooling costs over time. So, when selecting windows for your property, consider your climate zone, orientation, and energy efficiency goals.

Read this next: How to Achieve a 7-Star Energy Efficient Home with the NCC Changes in Mind 

What is SHGC?

SHGC, or Solar Heat Gain Coefficient, tells you how much of the sun's heat comes through a window.  When you see a SHGC, it’ll be shown as a number between 0 and 1.

Here’s how SHGC works:

• If a window has a SHGC of 0.6, it means that 60% of the solar heat hitting the window passes through to the inside.
• If a window has an SHGC of 0.2, only 20% of the solar heat hitting the window is transmitted.

The best SHGC rating for your home is determined by various factors, including the placement of windows (east vs. west), Low E coatings, and the climate you live in. For example, in hot climates, windows with a low SHGC are beneficial to keep cooling costs down, while in colder climates, a higher SHGC can help reduce heating costs. 

Understanding and optimising SHGC can lead to significant energy and cost savings, improved comfort, and a reduced environmental footprint. So, it’s always beneficial to pay attention to this window term when you’re renovating or building!

Read this next: A Comprehensive Guide to Energy Efficient Glass for Windows and Doors

WERS Ratings

The Window Energy Rating Scheme (WERS) rates the energy impact of windows in housing and commercial applications in Australia. It provides a “star rating” for a window’s energy efficiency performance. The more stars in a WERS rating, the more energy efficient a window is.

Stars on WERS ratings:

• The stars on WERS ratings are a simple way to understand a window’s energy performance. A higher star rating results in a more energy efficient window, which means it will do a better job of keeping your home warm in the winter and cool in the summer, helping reduce your energy bills.

WERS ratings take into account factors like U-values and SHGC to provide an overall energy performance rating. This makes it easier for consumers to compare different window products and choose the best option for their specific needs. For instance, a window with a high WERS rating will have both low U-values and an optimal SHGC for the given climate, ensuring maximum energy efficiency.

Next steps: Choosing energy efficient windows 

Selecting the right windows for your home involves understanding various window terms and how they impact the energy efficiency of your build or project. By familiarising yourself with concepts like what are U-values, what is SHGC, and WERS ratings, you can make more informed decisions that will enhance the comfort and energy efficiency of your home.

For more information on the latest in energy efficient window technology, read the guide linked below.

Read this next: What Are Thermally Broken Windows and Doors? Understanding the Latest in Energy Efficiency

At Stegbar, we’re experts in windows and are here to help you make the right decision about the products you put in your home. With over 75 years of experience, our knowledgeable and inviting staff are ready to assist you. If you have any questions, don’t hesitate to reach out to us or visit your local showroom. We’re here to help!