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  Secondary Glazing Systems - Selectaglaze Ltd  
 

SECONDARY GLAZING – THE SOUND ALTERNATIVE TO REPLACEMENT WINDOWS

Secondary glazing, not to be confused with double-glazing, involves the installation of an additional internal glazed window. These inner windows offer a number of distinct advantages but the main one is soundproofing.

In addition to noise insulation, secondary glazing provides draught proofing, improved thermal insulation and added security. And, where laminated glass is specified, the damaging affect of UV light is considerably reduced.

Noise is perhaps one of today’s biggest environmental problems. Noise is basically unwanted sound, originating from a multitude of sources, including traffic; aircraft; trains or other people’s work and day-to-day activities - any of which can have an adverse effect, disturbing concentration and creating stress. Sound is measured as a pressure, which is expressed in decibels. 0dB marks the threshold of hearing whilst 120dB is the point at which pain is experienced.  The human ear responds to loudness, which is dependent on both the Sound Pressure Level (SPL) and the frequency of the sound. The ear is more responsive to higher frequencies, which therefore appear louder. Measuring equipment can be weighted to mimic this reaction and the measurements are then defined as “A” weighted – or dBA. As a guide, 20-30dBA relates to a typical bedroom at night; 50-60dBA is a typical office and 70-80dBA represents average traffic. The measurement scale is logarithmic, so an increase of 10dBA approximates to a doubling of the noise level, whereas a change of 3dBA is just about noticeable. At best, a sealed unit constructed from two panes of 4mm glass with a 12mm cavity will provide a sound insulation level of about 30dBA, compared to secondary glazing, set at an air space of 100mm or more, which will improve sound insulation by 37 – 40dBA.

Thermal insulation is also of prime concern. The thermal insulation characteristic of a material is expressed as the U-value. This measures the transfer of energy across the material in W/M2K and a low figure indicates higher insulation capability. Glass with a U-value of 5.4 is a poor thermal insulator and readily conducts heat. A second pane of glass traps an insulating mass of air which then reduces the loss of heat. A typical sealed unit constructed from 2 panes of 4mm glass with a 16mm cavity will have a U-value of 2.65. As the air space increases, convection within the cavity will help transmit the heat from the inside pane to the outside. A secondary window will not, therefore, be quite as efficient but can still achieve a U-value of about 2.9. However, this can be improved upon by specifying a hardcoat low emissivity glass. More importantly, a secondary window with its efficient perimeter seals and brush or compression seals to opening panels markedly reduces heat lost through draught.

Improved Security is achieved with secondary windows creating an additional barrier to entry, even with the simplest of catches. But far higher levels of security can be achieved with the introduction of multi-locking systems and anti-bandit glazing, which can be up to 12mm in thickness.

A wide range of secondary glazing systems are available and can be tailor-made for specific projects, allowing existing site lines to be matched, preserving the original style of buildings undergoing refurbishment and meet the most stringent specifications for environmental upgrade.

Secondary windows are generally constructed from aluminium sections. An extensive range of paint and anodised finishes allows close match to the interior décor and the units will accept a range of thickness and specifications of glazing.

Information courtesy of Royal Warrant Holder Selectaglaze Ltd., the UK’s leading designer, manufacturer and installer of secondary glazing systems. A comprehensive range of literature is available, upon request, from: enquiries@selectaglaze.co.uk, 01727 837271/fax: 01727 844053. Or visit the company’s website: www.selectaglaze.co.uk

 
   
  Tel:    01727837271
Web: http://www.selectaglaze.co.uk
Email: enquiries@selectaglaze.co.uk
 
Fax:   01727844053
   
   





















     
 

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