If you live in an area where winters are particularly long, you may find it to your advantage to trade in traditional windows for double-glazed units. There are many benefits associated with the latter: double-glazed windows are more energy efficient and harder to break. They also do a better job of reducing noise.

So how exactly does double glazing work? Contrary to what many people think, the principle behind the technology is quite simple, but it pays to understand the science to help you make better decisions about which features are worth your time and which are just marketing gimmicks.

First, two glass panels are held together in a frame. The glass panels used in double glazing are usually tinted, although clear varieties do exist. The tint helps absorb solar radiation so that during the hot summer months, your home doesn’t feel like an oven.

The most common tints are bronze, grey, blue and green. High-end glass panels may employ a combination of reflective, anti-glare, and heat-absorbing technologies.

Second, an air or gas barrier is maintained between the two window panes. Called a spacer, this space is key to reducing heat loss and noise. Heat will always move from a higher temperature to a lower one. In solids (such as glass), this happens very quickly because the particles are packed so tightly together.

Heat transfer is much slower in gases (such as air or argon trapped in the spacer) because the particles are not only free-moving but also located far apart from each other. The effect is improved insulation. The heat does not easily escape through the window. Your home stays warmer for longer.

Sound travels slower through the air and explains how double glazing can keep noise levels down. Additionally, some spacers come with foam padding designed to absorb echo and dampen sound. This is a great way to host late night parties without disturbing the neighbors.

Finally, the barrier is sealed to prevent the entry of outside air and to prevent the accumulation of moisture on the interior windows. Conventional spacers contain desiccant as an added precaution against condensation.

There are several factors that can affect the overall efficiency of double-glazed windows. These include the type of window frame used, the thickness of the glass, and the space between them.

Regardless of the variables, all double-glazed windows work on the same basic principle. Traditional windows use only one pane of glass, while double glazing uses two. Between the two glass panels is an air or gas filled barrier that works to reduce heat loss and regulate heat gain.