What is double glazing?
Double glazing has become a familiar sight in most homes across the UK due to it’s many benefits. Cutting utility bills and reducing noise pollution are some of the many reasons that double glazing has become a popular choice for consumers 1. But do you know what double glazing is and how it works? We’ve put together some handy information explaining the mains benefits, what to look out for when buying double glazing and exactly what double glazing is.
What is double glazing?
Double glazing is created when you trap gas in between two panes of glass. Generally, these panes of glass will be of the same width, ranging from 3mm to 10mm in thickness. The gas filled space in between the panes of glass is the main reason for the reduction of heat transfer from a building, resulting in a more energy efficient window. The two panes of glass will be separated by a spacer bar and sealed in place creating an airtight unit.
Where did double glazing develop from?
Double hung and storm windows are an older form of glazing where double glazing is said to have evolved from. This older form of technology consisted of a single pane of glass separating interior and exterior spaces. To keep insects and animals out in the summer, a window screen would be hung, with a storm window being added in winter to create a double layered effect for insulation.
Types of glazing
Double glazing can be achieved using many different types of glass. Safety glass is one of the more important types of glass and is mandatory in many building types including schools and roof windows to avoid injury 2. There are also areas around the home, known as critical areas where safety glass must be used. Doors and panels adjacent to doors within 1.5m from floor level as well as low level glazing such as windows that are within 0.8m from floor level must be glazed in safety glass 3.
Laminated glass is a form of safety glass which is stronger and more durable than standard glass 4. It is constructed of two sheets of glass surrounding a plastic interlay sandwiched in between. This manufacturing process produces a pane of glass that, if broken, would continue to stick to the interior plastic layer reducing the risk of injury.
Five times stronger than standard glass, tempered glass is a form of safety glass which adds extra security and safety when used in specific areas 5. Tempered glass is subjected to intense heat followed by being rapidly cooled during its manufacturing process to produce it’s strength. To cause less injury, tempered glass is manufactured to shatter into hundreds of tiny pieces if broken.
How does double glazing help reduce heat loss?
The gas trapped between the two panes of glass in a double glazed window is key to the insulating properties that it produces. The gas typically used to create this insulation is Argon, which uses around 65% of the thermal conductivity of air, resulting in it being extremely inefficient at conducting heat trapping it inside the property. Energy efficiency of the property is also increased by the spacer bar used in the constriction of the unit. Our spacer bar for example, is 1000 times more energy efficient than standard aluminium, adding to the energy efficiency of the window and reducing heat loss in the property.
The importance of choosing the right double glazing
There are a few areas you have to look at when considering double glazing to ensure you are getting the most energy efficient glazing to keep your home warm and your energy bills down.
Ranging from poor (G) to excellent (A), windows are labelled with an energy efficiency rating set by the regulating body who have over 100 years of experience setting the expectations of products and companies across the UK.
There are a few specific numbers which are represented by the letters U, G and L which are awarded due to the overall properties of a window, not just the individual components. When considering double glazing, it is important to look at all the factors to make the right decision.
The U value of a window is the way in which heat loss is measured. When considering double glazing, the lower the U value is, the more thermal efficient your window will be.
The G value rating of a window is the scale which determines the windows solar gain. This scale ranges between 0 and 1 and indicates how much heat is let in by the window.
Air Leakage is the final factor to consider. Indicated by the L value, air leakage occurs if there is a weakness in the glazing unit. Most modern window units are air tight and should therefore have a L value of zero.
What types of double glazing frames are available?
Unplasticized polyvinyl chloride or uPVC, is the most popular type of window frame used for double glazing. With white being the most desirable, a variety of colours are available in uPVC window and door frames. Being anywhere up to three times cheaper than wooden frames 6, other benefits of uPVC include energy efficiency, durability and recyclability. Alternative options include aluminium and wooden frames. Wooden frames are more expensive and require more maintenance, which is why more people opt for the cheaper, longer lasting uPVC fames.
Further benefits of double glazing
Keeping homes warm and reducing energy bills are two of the main benefits o upgrading to double glazing. 44% of people surveyed by Which 7 upgraded to double glazing to keep their home warm, with 40% looking to reduce their energy bills. Having two panes of glass rather than one has other added benefits such as noise insulating. The second pane of glass in a double glazing unit acts as a noise barrier, keeping the property insulated from outside noise. Security is also another benefit as double glazed glass is more difficult to break than single glazed 8.