The Role of Vacuum Insulated Glazing to Make Homes Highly Energy Efficient

We previously talked about a variety of home improvements that can help improve energy efficiency. Some of them receive more attention, because they can have a huge effect. However, some of them are worth investing in, even if they don’t get the same amount of discussion. A great example is using vacuum insulated glazing.

Since most homes and buildings regulate their indoor temperature through heating systems, it is imperative that there is no heat loss toward the exterior of the building. Unfortunately, most of this heat loss is through the windows, something that can now be prevented far well than ever before.

Today, most buildings are designed to be aesthetically pleasing and large areas are covered with glass rather than brick walls. This means that there are even larger areas from where the heat created on the inside can escape to the exterior.

The technology of vacuum insulated glazing helps buildings and homes meet the needs for creating net-zero energy windows, reducing their thermal transmittance value. This prevents any energy loss from within, making the area highly energy efficient.

These glass units are also effective in preventing heat from the outside heating of the buildings during the hot summer months. This is both good for the environment and your wallet.

What is vacuum insulated glazing?

The idea for developing a vacuum within sheets of glass was first born in 1913, but it was many years later before it was perfected enough to hit the markets in the mid-1990s, starting from Japan. The inspiration for the idea came from the development of vacuum-sealed flasks for keeping drinks hot or cold. By creating a vacuum between two or even three rigid panes of glass, thermal efficiency is maximized, while sound insulation is also created. The higher the insulation provided the lower the U value is.

Usually, sheets of 3-4 mm thick glass are hermetically sealed together with a seal, and the evacuated cavity between them has less than 0.1 Pa. The glass is separated by 0.13 mm high and 0.3 mm in diameter support pillars made from stainless steel. The inter-pane cavity is the key element for these glass units because there is no medium to transmit heat and sound between the panes. This is achieved by the reduced pressure and the low thermal conductivity spacers absorb it. Triple vacuum insulated glazing has a U value of less than 0.1 W/m²K.

Research has shown that homes that had conventional glazing that was retrofitted with triple vacuum glazing, dramatically minimize their annual heating costs by 15.31% and the heat loss from their dwelling falls by 10.23%.

Why is it recommended: Why not gas insulated?

Until recently, glazing systems that were filled argon, xenon or krypton, all inert gasses, were widely used. Because these gases are denser than air, they reduce the transfer of heat. Argon has a thermal conductivity of 67% of the air, Krypton has 35%, and Xenon 22%.

However, in areas with lots of windows, especially commercial buildings, it is far more practical to prevent the solar heat radiation from entering and this is one thing that these windows aren’t efficient at doing. There is also the risk of a gas leak, because of pressure differences between the inside and outside and these gases escape naturally, at a rate of 1% a year, even when the window is perfectly constructed. This is caused by daily and seasonal temperature changes that cause the gas to expand and contract alternately. The insulating gas is squeezed through the seals, and with time, these fail.

As the gas escapes, the insulated windows lose their insulating performance and there is also the chance that the center glass in a triple glazing unit might collapse. This ends up looking unsightly, and there is a possibility that the glass could break. There is also the consideration that Krypton and Xenon are very expensive, pushing up the price of making these types of windows. Even though Argon is cheaper, again the cost of using it for making windows increases because of the time needed to fabricate them with the gas.

With vacuum glass systems there is no fear of anything escaping as there is no gas. This is the reason for them being more efficient and are fast replacing gas filled glazing as the chosen window type. They can be fitted into many types of frames, but with wooden ones, they reach an even higher level of efficiency.

How this type of window works for energy efficiency

• A vacuum is by far a better insulator because there is no air or gas molecule to transfer any heat transfer.
• The thin vacuumed gap ensures that there is nothing to conduct the transfer of heat and it is only a fraction of a millimeter wide.
• The completed units have half the thickness of conventional double-glazed glass.
• The windows are waterproof and airtight and cannot absorb moisture between the panes thanks to the inorganic seals that are used to seal the edges of the units. These thermally separate the inner and outer panes and form a continuous thermal short circuit.
• E-coatings also help to slow the transmission of external radiant heat.
• The panes are kept from touching each other by a series of fine beads that are arranged in a grid pattern and they take up a minimal amount of space to ensure that hardly any heat loss is allowed.

Is it safe enough to use?

Not only does vacuum insulated glazing maximize thermal efficiency, but also it has no gas between the spaces of the glass panes. There are other additional benefits, and besides the fact that there is no danger of any gases escaping, which will cause the glass to look unsightly or even to break, they are much thinner and suitable for many applications and façade designs.

Custom sizing this type of glazing is easy, and these can be made available for many building projects. They are ideal as replacement windows in any building where renovations are being made and are ideal as retrofits in older buildings. Even historic buildings can now consider changing their windows safely while also making them more energy efficient.

Therefore, vacuum insulated glazing has less weight and bulk, and provides the energy efficiency that regulations require, helping people achieve their desire to preserve the planet and its resources.