Glass is glass, isn't it ?

When it comes to glass there are two main issues to consider, namely the appearance of the glass and the performance of the glass.

The appearance of the glass can be altered extensively and be used to add to the character of a property.  Features such as Georgian bars and lead can be added to glazing panels to match the period styling of the property.  Other ornamental features can be added, including bevelled and colour glass, to give the look of a classic "stained glass" window.  All of these features are increasingly common, in a wider variety of styles and are no longer as costly as they once were.

The performance of the glass is a more complicated issue, with the different types of glass all looking the same to the untrained eye.  There are really four main aspects of glass performance that you need to be aware of.  These are:

• Low emissivity glass - The use of "low-e" glass has become almost mandatory since changes to the Building Regulation in April 2006.  This type of glass has a microscopic metal or organic coating, which results in up to 30% less heat being lost through the window, by reflecting it back into the room. An energy rating scheme for windows has been developed using the A-G catagorisation commonly seen on white goods - www.bfrc.org.
  
  
• Toughened glass - This type of glass is up to seven times stronger than normal glass and is created using a special cooling process.  Another advantage of toughened glass, is that in the unlikely event of it being broken, the pane will shatter into tiny, blunt pieces (similar to a car window), rather than the large razor-sharp shards ordinary glass breaks into.  It is also worthwhile considering using toughened glass anywhere that the young or infirm may be able to reach.
  
  
• Laminated glass - This type of glass consists of a sheet of film sandwiched between two panes of glass.  Because the film remains intact once the glass has been broken, similar to a car windscreen, it can help to prevent opportunistic burglars from climbing through without a lot of noise and wasted time.
  

• Acoustic performance - For many people this will be one of the main reasons for have replacement windows fitted in the first place.  Most people know that double-glazing keeps out more noise than ordinary single-glazing, however, not so many people know that the effectiveness of the double-glazing depends on the size of the air gap between the two panes of glass.  Simply, the larger the gap the more sound it will keep out.