uPVC Window Facts
Windows play a vital role in regulating temperatures of buildings and their overall energy efficiency, whatever the climate. Energy efficiency is not just about preserving heating in homes in winter; it is also about preserving artificial cooling in summer.
Today, high-performance windows are increasingly gaining acceptance in Australia as rising energy costs are prompting homeowners to consider the role of windows in their homes.
Why Choose uPVC windows in Australia
uPVC (unplasticised PVC, or vinyl-framed) double-glazed windows not only perform well in keeping cold out of a building and heat within; they also work to keep summer heat out and the cool air inside.
Well-established in Europe, the UK and the US where they are the dominant window type used, a key benefit of uPVC high performance windows is their ability to balance optimisation of heating and cooling loads with consumers’ desire for greater natural light.
The excellent thermal insulation of the uPVC frames combined with insulated glass units and airtight sealing means less energy is needed to maintain an ambient temperature within the home, which is reflected in cost savings, lower energy bills and improved levels of comfort. This makes them an ideal energy-efficient and cost-effective solution for Australian homes where homeowners like large areas of glazing and plenty of natural light.
Research by the CRC for Low Carbon Living reveals that 87% of consumers want a home filled with natural light and 85% want a cool home in summer and a warm home in winter.
Research conducted by Climate Works for a report, Built to Perform: An Industry Led Pathway to a Zero Carbon Ready Building Code, published by the Australian Built Environment Council (ASBEC) found that double-glazed windows are one of a number of simple measures to improve building performance that would be cost-effective to meet proposed stronger energy efficiency requirements of Australia’s National Construction Code. The analysis found that upfront costs of such measures would be more than offset by the energy bill savings, reduced spend on heating, cooling and ventilation equipment, and electricity network savings.
Modern uPVC windows are made from a rigid and dense material that is used worldwide for a variety of building products. The multiple chamber construction of uPVC windows gives them excellent thermal performance and strength, plus the frame’s low conductivity limits the transfer of heat and cold. uPVC is roughly 1,000 times less conductive of heat than aluminium. Thermal performance is further enhanced by a typical 16mm Argon Gas filled gap in the insulated glazing unit commonly found in uPVC windows.
Argon between glass panels is super important. It helps with noise because argon is more dense than air, it also helps with temperature control for the same reason.
But the biggest reason argon gas between glass panels is so important is that argon eliminates the risk of condensation between the glass panels.
Advances in PVC formulations, including a ‘tropical’ version for extreme heat and UV, have improved resistance to environmental conditions, such as heavy rain, warping, cracking or splitting, making uPVC windows a sound choice for Australian and New Zealand climates. With high resistance to weathering, salt-corrosion and termites, low-maintenance uPVC windows are also an excellent choice for coastal locations.
Today’s uPVC windows not only perform well, they look good, are available in a range of colours and offer superior security, thanks to advances in hardware and locking systems. Commonly used in Europe, the tilt-and-turn opening system provides great versatility for ventilating the house and ease of cleaning from inside the building. For example, in tilt mode, the top of the window tilts forward into the room venting hot air outside while preventing cool air nearer the floor from escaping. The tilt function allows ventilation at night with the peace of mind of security.
Moving the handle into the next position enables the window to be fully opened like a hinge door, allowing for cleaning or additional ventilation. Also available is a tilt-and-slide system with similar sealing properties to the tilt-and-turn versions, but better than standard sliding windows which rely on brush seals (which keep bugs out, but not air).
Quality uPVC windows have a lifespan comparable to that of aluminium and are recyclable at end-of-life. With their in-built thermal-efficiency, they are up to 40 per cent more efficient than a standard aluminium window, making them a worthwhile investment in today’s energy-conscious world.
With more window companies offering uPVC windows in Australia amid a growing market, they are becoming an affordable and sustainable fenestration choice for 21st century living.
In testing, based on an average house containing 8% area of glazing in the entire building fabric (windows, walls, floor and roof), as much as 49% of the heat lost during winter and as much as 87% of the heat gained during summer can come from the windows.
The U-Value or Uw is a measure of conductivity of the whole window (glass and frame included). It is a number calculated to return an amount of energy flowing through the product at a given temperature difference per meter squared of window. The Uw is a number that indicates how well a window or door will retain heat in the winter and reject heat during summer. The lower the Uw the better the energy efficiency of the product.
The Uw can be affected by the frame material and the glazing type. For example, aluminium conducts energy more readily than timber or uPVC and as a result aluminium products will have a higher Uw than timber or uPVC with the same glass. High performance glass can also have an impact on the Uw of the product. When a frame is fitted with higher performance glass like double glazing or low emmisivity glass, the Uw will fall making the product more energy efficient.
The SHGC or Solar Heat Gain Coefficient is a measure of the amount of heat that can be gained through your windows at times of direct solar contact. The SHGC is important as during summer the SHGC can add large amounts of unwanted heat to your house. Equally in winter, the SHGC can be utilised to provide cost and pollution free heat from the sun. The solar heat gain is measured as a coefficient and indicates the amount of direct solar heat that will penetrate your house.
The SHGC is mainly affected by the glazing type. Products like tinted glass and applied films can help to reduce the SHGC. It is important when selecting windows and doors that the orientation, location and house design are all considered to achieve the best outcomes. In cooler climates it is often advantageous to have a higher SHGC and in hotter climates a lower SHGC is better.
Cost of Running Ducted Air Conditioning In an Average House in Australia
|Hours per day||Summer cooling costs||Winter heating costs|
Calculations assume cooling costs of $3/hour and heating costs of $1.80/hour, based on an electricity usage rate of 35c/kWh. Calculations assume stated usage per day for 90 days.
According to research, an average Australian house uses 9 hours of ducted air-condition cooling or heating per day.
So, according to the above table, an average Australian home with ducted air-con will consume $3,888 per annum for heating and cooling with standard aluminium single glazed windows.
Considering the uPVC double glaze windows are up to 70% more efficient than the standard domestic aluminium single 3mm float glass, we can assume the savings will be as follows:
$3,888-70%=$1,166: that is a saving of $2,722 per annum on the energy bill at the current prices, and we all know that the energy prices are on the rise annually, so the longer the time of the uPVC double glazed window use, the more you save on the energy bills.
* The above calculations are an example only and it is not tailored to any individual needs, nor should it be used as a standard for any existing or new energy saving calculations. All clients should do their own research and calculations to determine the savings on their energy bills using uPVC double glazing windows.