Everything you need to know about double glazing

Double glazing windowsAre you renovating or building a new home? When it comes to choosing windows and doors, it’s important to understand your options, writes Chris Godden.

Windows are no longer all made in standard one-size fits-all options – today, buildings are designed with entire walls of glass, glass ceilings and internal windows. But the energy bills to keep these homes warm must cost a fortune, right? Wrong. With the technology of double glazing, the options for larger, uniquely shaped and positioned windows are now endless. Below is your complete guide to double glazing before you jump into choosing your new windows and doors.

What is double glazing?

All windows were once made with a single pane of glass. Glass is typically a poor insulator because it is only a few millimetres thick. This means it’s easy for hot and cold air to pass right through, making climate control in the home difficult. Double glazing is a solution designed to combat this, by using two panes of glass with an air gap in between. The combination of glass and the air gap makes the windows stronger insulators, keeping the temperature inside more regulated. This saves you money on heating in winter and cooling costs in the warmer months.

How does it work?

Whenever there is a difference in temperature between the outside and inside, heat flows through the weakest points of your home. This is usually the windows, doors, or cracks in floorboards or uninsulated ceilings. In summer, heat flows from the outside in, while in winter heat leaks out.

Double glazing is designed to slow heat flow, making your home more energy efficient. Two panes of glass make the window more insulated, as the thicker the glass is, the more difficult for heat to pass through it. Similarly, having the air gap between the two panes of glass provides a barrier to block the heat. When a material (take glass for instance) is hot, its molecules move quickly, spreading heat fast. Because air molecules are spread out they cannot spread heat as quickly as a solid mass like timber or bricks. Having the air gap therefore stops the movement of heat through the window.

Is all double glazing the same?

There are variations of double glazing, suited to different climates and weather conditions:

  • Standard double glazing, which is simply two panes of standard glass and is suitable for most climate conditions.
  • Smart Glass is a low-e glass that has a protective anti-glare film to reflect harsh sunlight and reduce heat gain in warmer months. When used in a double glazing unit, this greatly increases the insulation of the window.
  • Thermal glazing is ideal for extreme climates and climates with highly variable temperatures. Thermal glazing uses smart glass in either double or triple glazing units and can increase the insulation of a window by up to 68%.

Can I double glaze existing windows?

Many windows can be retrofitted with double glazing. This means a second pane of glass is fitted to the outside of your existing window. This can, however, be a costly process and changes the look of your facade. Most glaziers will recommend replacing the entire window unit including the frame with a new double glazed unit. In many cases the cost will be similar, and results in a brand new, longer lasting window.

Do double glazed windows get condensation?

The change of temperature between night and day, as well as the difference between inside and out, can cause a build-up of moisture on your windows. This prevents your windows from fogging up, as double glazing units are usually fitted with an absorbent desiccant (absorbent spacer in between the panes of glass). While this will prevent most condensation, depending on your climate and the position of the windows, you may notice small amounts of condensation between the glass from time to time. This is nothing to worry about.

Cleaning your double glazed windows is no different from cleaning any other glass windows and doors. Regular cleaning of dust and dirt, combined with periodic spray and wipe of the glass with a glass cleaner, will keep your windows clear and clean.

How much does double glazing cost?

The cost of double glazing varies, depending on the type of glazing you choose, the frames and the quality of the product. When calculating the cost of double glazing it is important to consider how much you will save in energy bills by choosing double glazing over single glazing. Perhaps even calculating how long it will take to pay off with the savings gained. Some factors that will influence the cost of double glazing include:

  • Type of glass: Plain glass or smart glass.
  • Thickness of the glass.
  • Double or triple glazing unit.
  • Aluminium or timber frames.
  • Any other glass treatments (e.g. frosted, tinted, anti-graffiti film).

When building a new home or refurbishing your current abode, ensuring you choose the best technology and fittings for your lifestyle is important. By choosing double glazing, you can guarantee your home will be more energy efficient and comfortable for years to come. An investment in your new home, double glazing will save you money and minimise your eco footprint.

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