Double glazing is formed from two panels of glass sealed together, with some space left between them. The air or inert gas (usually argon) trapped between the panels creates a pocket of insulation that keeps heat in or the cold out.
Double glazed windows offer nearly twice the insulation single units have. Reducing heat loss, noise, and condensation. Once sealed, the unit becomes airtight and the glass is then fitted into wider window frames that can accommodate the two panes.
For all their advantages, however, you should note that these windows cost at least 25% more than single glazed windows. It may take 5 years or more to recoup the extra cost but on the long term, you can save approximately 25% on your total energy consumption bills.
Another disadvantage is that the heat trapped by the panes can be uncomfortable and stuffy in the summer. This can be tackled by tinting the windows to keep out the heat, which attracts an extra cost.
Double glazed windows usually have a lifespan of 20 years. Yet poorly-installed windows can still fail much sooner. Though double glazed windows can be repaired, the cost involved is usually restrictive since the frames may need to be replaced as well.
When the glass inside the windows becomes foggy or misted, it is a sure sign that the glass or the seal is broken. A broken seal is usually caused by cleaning material agents used on the seals.
Benefits of double glazing
- Saving energy costs - Double glazed windows help to create thermal insulation. This helps in keeping the heat out in the summer and the warmth in during winter.
- The double glazed windows allow natural sunlight in while preventing the room from overheating.
- Safety - Double glazed windows are tougher to break therefore increasing the security in the building.
- It ensures a quieter home - Double glazing helps reduce the noise that may enter from outdoors.
- Reduces condensation - Condensation can result in the harmful formation of mould. The air between the two glass panes and the airtight seal prevents the buildup of condensation by blocking moisture in cold weather.
- Reduces furniture damage and interior fading - Double glazed windows made from UV resistant glass reduce the damaging effects of UV light on drapes, carpet and furniture. This also the advantage of minimizing the need for thermal drapes that can block the view outside.
- Enhances the resale value of your home: Double glazing is an excellent investment that increases the resale value of your home. Double glazed windows aid in ensuring that your home has a high Star Energy rating. A study by the Australian Bureau of Statistics showed a positive correlation between higher star ratings and higher resale prices for homes.
- Reduce your carbon footprint-Double glazed windows can reduce the greenhouse gas emissions produced when heating and cooling the house.
Type of glass and material used
The frames of double glazed windows can be made from 3 materials. These are:
- Timber- it is a good sound and thermal insulator. Yet timber frames often have gaps between them which can cause draughts Timber frames are also expensive to buy and maintain and degrade easily.
- Aluminum- this is the cheapest material for window framing. These frames are strong, durable and light. Unfortunately, aluminum is a very good conductor of heat and cold and can potentially decrease the energy values of your windows.
- PVC- windows made from PVC have the best acoustic and thermal qualities. They are also easy to clean, last long, and have the lowest maintenance.
A wide range of glass types can be used in double glazing units to further increase energy efficiency and noise control. These include low-emissivity or low-E and laminated glasses that are commonly used.
Low-E glass will reduce the amount of heat escaping as it has a transparent metallic coating that economises heating energy. Laminated panes are a thicker option that aid to disrupt sounds waves and improve noise reduction efficiency.
Window energy ratings
The main goal of double-glazed windows is to keep unwanted heat out, minimise the need for air conditioning, and reduce overall energy usage.
The rate of non-solar heat loss or gain through a window is measured by the U-value. Both the frame and glass panels are taken into consideration. A lower U-value indicates that the window has a greater resistance to heat flow and offers better insulation.
Windows and doors which offer good solar protection and can also minimise solar heat gain are said to have a low SHGC value.
With the rising cost of energy and the government tightening stringent building regulations, building owners are left with no choice but to choose the most effective thermal insulation glass[
Check the energy ratings for a particular state before choosing which window panes to install in order to meet the set out standards.
In addition to choosing the type of glass to use, energy ratings can be further enhanced by the spacing used between the glass panes.