It is better to install efficient windows than to rely on heating, ventilation and air conditioning (HVAC) systems to solve thermal comfort problems. Not only do HVAC systems create non-uniform interior conditions, only partly relieving thermal discomfort, but power outages on peak days can lead to extremely uncomfortable conditions.
Ordinary windows can represent a major source of unwanted heat gain in summer and significant heat loss in winter. Up to 40% of a home’s heating energy is lost and up to 87% of its heat is gained through windows. Installing energy efficient windows will improve the thermal performance and comfort of your home along with reducing energy costs and greenhouse gas emissions.
There are literally hundreds of glass and window types to choose from but selecting the correct one is critical to improving the energy efficiency of your home and reducing your energy costs.
With the Building Code of Australia (BCA) now stipulating regulations on energy efficiency, your window selection along with other factors determine the star rating for your home. Each state is slightly different due to their individual climate, and it’s important to understand what is best for your climate when selecting your windows.
The Window Energy Rating Scheme
So how do you compare the energy efficiency of different windows? The simplest way to do this is using the Window Energy Rating Scheme (WERS). WERS rates the energy impact of residential and commercial windows throughout Australia. Useful performance figures such as U-value and SHGC as well as air infiltration, condensation, fading and visible transmittance are provided. (Explanations of terms are detailed below)
How does the rating system work?
WERS-rated windows, skylights and glazed doors are accompanied by a label which certifies that the window has been tested by an independent accredited simulator and approved by a WERS auditor.