Parts of Australia enjoy some of the sunniest conditions in the world. In areas of Western Australia and the Northern Territories, Australians enjoy more than 9 hours of daily sunshine, but this can take its toll on your air conditioning bills. Keeping your house cool in sunny weather isn't always easy, but energy-efficient window coatings can certainly help. Learn more about these coatings, and find out how this type of glazing could help you.
How window design affects your home
Energy-efficient windows can cut heating, cooling and lighting costs, but homeowners must consider several factors when choosing glazing. The type of window you choose is important, but so is the house's position and the part of Australia you live in.
For example, if you live in a part of the country where you need to keep the house warm, you should try to maximise glazing in south-facing walls. In the winter, the sun is lower, so large, south-facing windows will make the best use of daily sunshine.
You can also look for various efficiency statistics to help you understand the energy performance of your windows. Things to consider include:
- U-factor, which describes how much non-solar heat passes through the glass. The lower the U-factor, the more energy efficient the glass is.
- Air leakage, which shows how much air you lose around the window. A low air leakage rating indicates that the glass is more energy-efficient.
- Solar heat gain coefficient (SHGC), which shows how much solar radiation can pass through the glass. A low SHGC means that the glass transmits less heat and will help you keep your house cool.
- Visible transmittance (VT) relates to how much visible light can pass through the glass.
Window coatings can improve the energy efficiency of your windows. These coatings can affect the U-factor, the SHGC and the VT of your windows.
Types of coating
Homeowners can generally choose from three types of coating.
A low-emissivity coating can help control heat transfer. You would normally buy glass with the coating, although a few manufacturers now offer DIY films that you can apply at home. Manufacturers use a very thin coating of metal or metallic oxide, which cuts the glass's U-factor, and you may also experience a lower VT.
Reflective coatings block out light. These thin, metallic coatings will dramatically cut VT and SHGC, but you may experience less natural light in the room. As such, you may offset some of the savings in heating and cooling with increased lighting bills.
Spectrally-selective coatings filter out 40 to 70 percent of the heat without cutting the level of light permitted through the glass. These coatings reflect certain light wavelengths, so you can keep the house cool without affecting the brightness of your rooms. A specialist supplier can normally apply this type of coating to any type of tinted window.
Cost of coating
The cost of a window coating varies according to several factors. Aside from the size of the window and the type of coating you choose, the cost of the work will increase if:
- You have smaller window panes (as you would find on a French door)
- You need the supplier to remove old film
- You have odd-shaped windows
- You need the supplier to remove putty, paint and other contaminants on the glass
In most cases, a window coating will increase the cost of new or replacement glazing, but the savings you make in reduced energy bills will normally offset the investment.
Choosing the right product
It's a good idea to compare multiple work estimates before you make a final decision. Make sure your supplier explains the benefits of different coatings, and ask him or her to confirm the energy efficiency that each product type can offer.
If you plan to use a DIY coating, confirm with a glazing specialist that the product is suitable for your windows. In some cases, you could void the manufacturer's warranty on your windows because some types of glass cannot cope with the effect of the coating. For example, if the glass heats up too much, you could break the factory seal or even the pane itself.
Window coatings can boost energy efficiency in your home, but it's important to choose the right product for your home. If you have any questions, contact a local glazier.