A Comprehensive Guide to Double Glazed Windows for Homeowners

Double glazing has become a popular choice for homeowners in recent years. Its benefits, from saving on energy costs to reducing noise pollution, make it a smart investment. If you're contemplating an upgrade to your windows, this guide will provide you with all the essential information on double-glazed windows. By the end, you will be equipped to make an informed decision.

What is Double Glazing?

Double glazing uses two panes of glass with a space between them filled with gas or air. This design creates an effective thermal barrier, preventing heat loss in the winter and minimising heat gain in the summer. A report published by RMIT states that windows are associated with up to 87% of heat gain, and up to 40% of heat loss in Australian housing.

The main goal of double glazing is to enhance thermal efficiency, ensuring your home remains comfortable year-round.

Benefits of Double Glazing

1. Improved Energy Efficiency

Double-glazed windows are champions of energy efficiency. By significantly cutting down on heat loss, you can maintain a stable indoor temperature. According to studies, homeowners can save as much as 20% on heating and cooling costs by switching to double glazing. This means that if your monthly energy bill is $200, you could save around $40 each month.

This adds up to enormous savings on energy, especially since our energy bills keep rising, which is six times the average pay increase. With no long-term solution to every increasing power prices, consumers need to look for ways to offset household energy costs. One way to do this is to install double glazed windows which in turn means dramatically reducing your power bill.

2. Noise Reduction

Living near a busy street or in a noisy area can be frustrating. Double glazing can reduce outside noise by up to 60%. The two layers of glass paired with the gas-filled space create a strong sound barrier, allowing for a much quieter and more peaceful home environment.

3. Increased Security

Another significant advantage of double-glazed windows is enhanced security. These windows are much tougher to break than single-pane options. Many homeowners report feeling safer and more secure knowing their double-glazed windows offer better protection against intruders.

4. Reduced Condensation

Condensation can lead to mold growth and damage your home. Double glazing helps to keep the inner pane warmer than a single pane would, which minimises the chances of condensation forming. This is especially important in areas with high humidity, as it can help prevent mold and maintain air quality.

5. Enhanced Aesthetics

Double-glazed windows come in various styles, colors, and finishes. Whether you're renovating or building, these windows can complement your home's aesthetic. For example, traditional wood frames can add a cozy touch to a vintage home, while sleek aluminum frames fit well in modern designs.

Disadvantages of Double glazing

1. Cost

The main disadvantage of a double glazed window is the added expense. There is no denying that they cost more than single glazing, which is why builders prefer single glazing as it keeps their outlay lower. The price difference between single and double glazed windows is perhaps 20-30% higher.

2. Upfront and retrofitting

If you consider the cost of replacing single glazed windows with double at a later date, the cost becomes almost double what the original cost would be.

Choosing the Right Double Glazed Windows

1. Frame Material Options

When picking double-glazed windows, consider different frame materials:

• Timber - Possibly the most expensive material to use, but very thermally efficient. They also have the highest ongoing maintenance due to timber rotting if it’s not maintained well. However, Timber aluminium cladding frames require minimal maintenance compared to traditional timber frames. The aluminium exterior protects the timber from external elements such as rain, wind, and UV rays, significantly extending the lifespan of the windows.

• Aluminium - Aluminium frames are possibly the strongest and most robust of all the different frames available, but they have the major disadvantage of conducting heat or cold straight through the frame. Aluminium frames with a thermal break are basically two frames that have been joined by an inert joiner that effectively reduces heat transfer across the frame. For this reason they are more expensive than normal aluminium frames, but the advantages of strength and thermal efficiency greatly out way the disadvantages.  
  

• uPVC - Usually, the lowest cost material to make frames out of, they have been used in the northern hemisphere for over 40 years. uPVC frames are thermally efficient. However, they usually require an additive here in Australia to combat high UV levels and internal aluminium or steel reinforcements for added strength. uPVC frames are effectively plastic and don’t perform well in bushfire zones. They also give off toxic gases in a fire situation.

  
  

2. Glass Types and Treatments

The type of glass in windows influences their performance. Homeowners may want to explore:

• Triple glazing: Whether it is necessary to choose triple glazing or not, it comes down to what is important to you. If you want a home with a 9 or 10 star energy report or you are building a passive house or you are really trying to reduce your energy bills to as low as possible, or you live in the high countries or near the coastline, then triple glazing is certainly worth considering.

• Low-E Glass: Low E means ‘Low Emissivity’ – emissivity is defined as the amount of radiation emitted or absorbed from a surface.

  The main difference between a Low E glass and an ordinary glass is that Low E glass has a very thin coating applied to one side of the glass. This enables a reduction in the transport of heat or cold through the glass. Think of it as an invisible insulation barrier for your windows. Just as wall and ceiling insulation provides protection to those areas, Low E glass does the same for glass. Coated glass helps provide a more comfortable temperature in a room, more window area can be used as an added bonus, and heating and cooling costs are reduced. Combining better insulated products into our homes makes sense and contributes to reducing greenhouse emissions.

3. Energy Ratings

Pay attention to energy ratings when shopping for double-glazed windows. Opt for windows with high thermal performance ratings. This will lead to ongoing savings and a more comfortable living environment.

• U value: In its most simple form, the U value is a measure of how energy efficient a window and frame are.

  
  

  The heat transfer through a window (or any part of a building) is measured using a “U value.” (measured in Watts / square metre Kelvin), The lower the U value is, the lower the rate of heat transfer.

  
  

  Double glazing typically has a much lower level of heat transfer than a single glazed window. A typical single glazed window has a U value of 5 or 6. While a decent U value for double glazing is around 2, figures of 1.5 are more than achievable.

  
  

  In general, the lower the U value, the more expensive the window will be.

  
  

• SHGC: Solar Heat Gain Coefficient or SHGC is a measure of how much solar radiation passes through the window. In a cool climate, windows which have a high SHGC allow a greater amount of solar radiation to pass through, offering free solar heating for the home. Glass selection as well as Low E coatings have a considerable effect on the SHGC of a window or door.

  SHGC is measured between 0 and 1. With 0 meaning no transmission of solar heat and 1 meaning all the solar heat is transmitted through the glass.

  So what is a good number and what is a bad number? Unfortunately, there is no correct answer to that. You need to determine how much heat do you want to gain from the sun and how much heat do you want to block?

  In a cool climate a higher SHGC will allow more solar heat to pass through the window and help to heat the home, whereas in a warmer climate a lower SHGC will allow less solar heat to pass helping to keep the home cooler.
  

  Glass tints and low-e coatings are some of the options to consider to get the best result for your home.

  Things to consider when choosing your windows are:

  • The climate of your build or renovation location.

  • What are the building materials that interact with the windows? E.g., insulation, cladding or other building materials.

  • The design of the building. E.g., orientation, layout window position and size, roofing or shading.

  • Double or triple glazing, thickness of the glass, types of glass and coatings also play critical role in manipulating SHGC.

Installation

1. Hiring Professionals

To ensure your double-glazed windows perform their best, it’s essential to hire an experienced professional installer. A proper installation maximises efficiency and longevity.

2. Initial Preparations

Prepare your home before installation by clearing the areas around existing windows. This ensures installers have unobstructed access to work.

3. Installation Day

The installers will remove old windows and carefully fit the new double-glazed units. Proper sealing and insulation during this process are vital for achieving the best energy efficiency.

Maintenance of Double Glazed Windows

Double-glazed windows are low-maintenance, but regular care can extend their lifespan:

• Cleaning: Keep the frames, glass, rubber seals / gaskets clean by washing with mild soapy water or non-abrasive cleaners twice a year. If you live close to the beach, clean monthly to prevent salt build-up.
  

  Keep the sliding window and door tracks as clean as possible. Build up debris such as dirt, sand and small stones can damage the track and rollers over time. Vacuum and wipe the track with a damp cloth regularly. 
  

• Check seals: Check the rubber seals / gasket yearly to ensure they are not brittle. Check glass to ensure no moisture between panes.

  
  

Final Thoughts

Double-glazed windows offer homeowners an excellent opportunity to enhance energy efficiency, security, and overall comfort. By understanding the various benefits, selecting the appropriate materials, and ensuring professional installation, you can enjoy the numerous advantages of double glazing.

Considering upgrading to double-glazed windows to improve your home's functionality, comfort, and beauty? Contact us via m@mlwindows.com.au or learn more about ML Windows at https://www.mlwindows.com.au