If you are building or renovating your home, it will only be a matter of time before you will face a decision whether to buy single or double glazed windows. Most of us understand that double glazed windows provide better insulation than standard windows. We also know they cost more. Are double glazed windows worth the extra cost? When you know how double glazed windows work, you'll be in a better position to decide whether or not they are the best choice for you.

How Do Double Glazed Windows Work?

The secret to double glazed windows is in the space between the two panes of glass that make up a double glazed window. The trapped air in this space serves three important functions:

1. It acts as insulation, helping reduce the passage of hot or cold air between the inside and the outside of the house.
   
   
2. Double glazing helps prevent condensation from occurring inside the house when it is cold outside and warm inside.
   
   
3. Double glazed windows help reduce noise pollution by reducing the ability of outside noises to pass through the glass.

While double glazed windows do provide insulation from hot air temperatures, they do not provide insulation from radiant heat. If direct sunlight strikes the window, its heat passes through unobstructed. To help reducethis, special ultraviolet (UV) light blocking window tinting is required. This works equally effectively on both single and double glazed windows.

All Double Glazed Windows Are Not Alike

What is inside the air cavity between window panes makes a difference to their performance. Standard windows simply trap natural air between the panes. This is highly effective, but other glazing techniques are said to be even more effective:

• Nitrogen gas filled cavities are said to increase insulation properties.
  
  
• Argon is another gas that is used in manufacturing double glazed windows. Manufacturers of these windows claim argon is even more effective than nitrogen.
  
  
• Laminated glass windows consist of a thin plastic membrane sandwiched between two layers of glass. Most often used in commercial structures, they are also available for home use and provide greater insulation as well as being shatterproof.
  
  
• Thermal glass also has a thin membrane designed specifically to cut UV radiation and prevent radiant heat from passing through. This type of glass is used in manufacturing skylights.

Your choice of windows will depend on the amount of insulation you require and whether or not nor windows are exposed to direct sunlight. If part of your problem is radiant heat from direct sunlight, installing awnings in addition to double glazed windows will greatly increase their effectiveness. Where this is not possible, choose tinted or thermal glass.