Choosing the right ‘performance glazing’ or energy-efficient glass and frame combination will determine how much heat enters or escapes the home.
It has become more apparent in recent years that regular, single clear glass windows will not be adequate to meet the increased building regulations set by the National Construction Code (NCC) for new and current home designs. Single clear windows are notorious for unwanted heat gain and heat loss as they only have one ‘single’ pane of glass allowing heat to enter or escape very quickly.
Understanding Windows
There are a number of glass attributes that affect a window’s efficiency.
- The number of (glazes) panes of glass
- The thickness of the glass
- Coatings on the glass
- Space between the glass
- The material separating the glass (spacers)
- The gas between the glass
- The frame holding the glass in place.
There’s a little more involved than most people are aware and that is why House Energy Ratings, such as NatHERS are so important. They are the only standardised unbiased measurement (tested and measured by a neutral authority) available to help consumers make an honest comparison between windows.
“Glazing is a significant investment in the quality of your home. Studies show that a home can achieve an increase of 2 to 2.5 stars by simply going from the worst-performing windows to the best-performing windows.”
However, there is no ‘one size fits all’ solution.
No single window can claim to ‘make’ a house achieve 6-stars. What works well in Cairns will not necessarily be suited to a home in Hobart, and this is where thermal performance modelling software such as FirstRate 5, HERO, AccuRate, or BERS pro is assisting the building design industry to not only specify high performance glass and window types, but also educating consumers on factors such as orientation, eave placement and whether to have 90% openable louvers or fully fixed windows.
Note: It is also important to note that two identical homes, located in the same climate zone, for example Cairns, may require different windows or glazing to achieve a given star rating due to their different orientations.
For many years, the effect of glazing on energy performance, home comfort and safety has been greatly under-utilised in Australia. Poorly designed windows and inefficient glass has made many a home too hot in summer or too cold in winter, increasing demand to use artificial heating and cooling systems. – Australian Window Association
Well-chosen window glass will help you maintain year-round comfort and even reduce your power bills as well as making your home safe and secure. There are literally thousands of glass types available to use in your home windows. The choice in glazing options has grown dramatically in recent years.
Factors to consider when building a new home:
Before moving onto what window glazing is best suited to hotter V cooler climates, there are many factors to consider when designing or building a new home including:
- The climate zone your new build or renovation is located.
- What are the building materials that interact with the windows?
- Including insulation, cladding or other building materials.
- The design of the building.
- Including the orientation, layout window position and size, roofing, or shading.
- Glass type being used.
- Integrated glass units and the types of glass and coatings also play critical role in manipulating SHGC.
Discuss the above factors with your Building Designer during the concept stage of your new build or renovation and/or engage an expert in either Passive Design or Residential Energy Efficiency.
Tip: If you want coatings on your windows, make sure they are factory installed and come with a warranty.
