Glazing

Did you know that Up to 40% of a home’s heating energy can be lost through windows.

Windows are complex and interesting elements in the fabric of a home. They let in light and fresh air and offer views that connect interior living spaces with the outdoors. However, windows can be a major source of unwanted heat gain in summer and significant heat loss in winter.

Energy efficient windows make your home more comfortable, dramatically reduce your energy costs and help to create a brighter, cleaner and healthier environment.

Windows can severely impact on the heating and cooling loads of a building. Up to 40% of a home’s heating energy can be lost and up to 87% of its heat gained through windows. Improving windows’ thermal performance reduces energy costs and greenhouse gas emissions.


Thermal properties of glazing

There are literally thousands of types of glass and frames to choose from. Selecting the right ones is critical to improving the energy efficiency of your home. Specific products have been designed to keep heat in or out and have varying impacts on daytime lighting, noise control, maintenance and security.

Types of glazing

A wide variety of glass products are available. The thickness of glass has negligible impact on its U-value and SHGC. However, it does have a significant effect on noise transmission and the strength and safety of the glazing.

Low-emissivity glass (or low-e glass as it is commonly known) is a type of energy efficient (insulating) glass designed to reduce the transfer of heat or cold through the glass.  That means in the winter your house stays warmer, and in the summer – cooler.

Low-e glass is essential for rooms with a high proportion of windows or glass doors. 

By replacing your existing glass (which in older houses is only 3mm thick) with low-e glass you will make the windows considerably more thermally insulated hence improving the energy efficiency of your home and helping to save money on your heating bills.

Laminated glass has a plastic glazing layer, called an interlayer, to improve impact resistance. This interlayer is placed between two sheets of glass in order to reduce the danger of the glass breaking and forming long dangerous shards. Typical applications include areas in the home most prone to injury from human impact such as bathrooms, doors, around staircases and in areas close to the floor. Careful selection of different interlayer types has the added advantage of addressing specific noise and energy efficiency requirements.

Insulated glass units (IGUs (Double glazing)) are the combination of two or more glazing layers sealed with a gap between the layers. Multiple layers of glass can be assembled with sealed cavities between each sheet. The performance of IGUs depends on the properties of each layer of glass and the width of the cavity, seal type and content of the cavities between the glass layers.

It is often wrongly assumed that insulated glazing is only for cold climates when in fact it achieves the best performance levels in both U-value and SHGC in all climates.

Secondary glazing allows single-glazed windows to be retrofitted with a transparent acrylic or glass sheet attached to the inside of the frame or operable sash via a secondary frame or magnetic strips. This creates an air space between the glass and the acrylic layer which reduces the U-value and air infiltration. It does not deliver quite as good performance as a manufactured IGU but does provide good noise control.


(information provided by The Australian Government - Your Home)

For further information please visit their web-site

www.yourhome.gov.au/passive-design/glazing?temp-new-window-replacement

Interesting Information -

www.washingtonpost.com/wp-srv/artsandliving/homeandgarden/daily/graphics/escape_routes_012507.pdf?temp-new-window-replacement