Double Glazing and Energy Efficiency

So what is double glazing? What are the alternatives? And how much do they vary from each other?

The answer is its 2 pieces of glass sealed together with a spacer bar around the boundary. But the description does not end there as not all double glazing is the very same. The glass unit can carry out differently depending upon numerous elements. These are;

  • Overall thickness
  • Specialised coatings
  • Spacer bar
  • Gas filling

Overall thickness of double glazing

The density of double glazed sealed systems have changed over the years. They began at around 12mm thick and, over time, they have got thicker. While the glass panes remain the very same at 4mm per pane (this can also change) the primary distinction in density has originated from the space in between the panes. We know this as the cavity.

Double glazing and its specialised finishings

The glass itself has actually changed over the years too. Double glazed sealed systems started their life using simple plain float glass. With the need for better energy performance came the requirement for much better carrying out glass. The glass sheet producers did this by altering the process used to make the glass. This new low emissivity, or Low E glass quickly became a popular upgrade. Because of the raw material modification, Low E glass had a brown/orange tint, however in more recent years this tint has actually ended up being more neutral.

Hard coat process

To produce difficult coat Low E glass, the glass producer utilizes a pyrolytic procedure (change by heat). With this specialised process they apply a microscopic layer of tin oxide straight to the molten glass. This develops a glass with a long lasting finishing making it easy to make into sealed systems. 

Soft coat procedure

The production approach for soft coat Low E glass is various. A microscopically thin layer of metal oxide is applied to basic float glass inside a vacuum utilizing a ‘sputtering’ process. This soft coat procedure includes a better U Value keeping more heat in your home. Because they apply this coating later on, it can be quickly marked so can be more difficult to deal with when making sealed units.

Other specialised glass

Integrating other types of expert glass can assist you control the temperature level in your house more effectively.

Anti-sun glass 

They can use Anti-sun or solar control glass to help control the temperature in rooms with big glazed locations such as conservatories. Anti-sun glass assists by limiting the sun’s rays while still permitting light in. It is readily available in a variety of tints everyone having different properties depending upon the homeowner’s requirements.

low iron glass 

Low Iron glass is another kind of glass where a modification in basic materials assists us achieve a better performing glass unit. Carefully picked basic materials help develop and ‘additional clear’ glass with a naturally low iron content. This glass has a high light transmission which makes it look clearer than basic glass. It likewise has a high solar heat transmittance implying it can help produce heat for your home from the sun. To actually see the distinction between these two types of glass it’s finest to look at them from the edge. The image reverse reveals the green tint of standard float glass and low iron glass without any (or little) tint.

Self-cleaning glass.

Designed for conservatory roofing and difficult to reach glazing applications, the self- cleaning glass works in 2 phases. Phase one involves a photocatalytic finishing that is applied to the external surface of the glass which responds to daytime and helps break down organic dirt. Stage 2 is hydrophilic. With the aid of the finish, when rain water strikes the glass it spreads out equally and diminishes the glass in a sheet rather than beads. As the water runs off uniformly it takes the loosened dirt with it, cleaning the glass without leaving streaks.

Spacer bar

The spacer bar is another part of the sealed unit that has improved throughout the years. It has actually aided with the energy effectiveness of double glazing while still performing the very same standard function. They bond together the glass panes and spacer bars assisting seal the space in between the panes of glass. The spacer bar is likewise filled with desiccant to help in reducing any residual wetness inside the cavity.


They still use aluminium spacer bars in double glazing, however because of its poor thermal bridging homes, it ended up being a less popular option.

Warm Edge

Warm edge spacer bars aid control thermal bridging between the panes of glass. This assists increase the energy effectiveness of the glass unit and the window or door it is in.

Double glazing and its gas filling

Glass unit manufacturers fill the area in between the glass panes with an inert gas such as Air or Argon. The gas utilized inside the cavity of the double glazed sealed system can affect its performance.

Air and argon gas filling

For a long period of time, air was the gas used to fill the cavity of double glazed sealed units. In the quest for lower U Values less inert gases such as argon gas began to become a popular alternative. Argon gas has a lower thermal conductivity than air (around 34%). 

Other gases

Krypton and Xenon (noticable zen-on) are examples of other gases utilized inside the cavity of a sealed glass system. These gases are not that typical in energy effective sealed units since of their expenditure. When these gases are specified within a sealed system, it is normally for heritage properties where the glass units need to be thin.

The future of glass and double glazing

Glass innovation will continue to advance. The energy efficient finishes applied to the glass will also continue to improve. This will assist your new windows and doors become more effective at keeping your house good and warm. Contact Newham Glass for all your Glazing needs – Check out our Testimonial Page.

Obviously no one outside the system companies understand what they are working on next. What we do know is that glass will significantly become an important product in the building and construction of structures. As homeowners require more light and much better U values the technology used to make glass will advance. So who knows what will be next … Touch screen windows?

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