Selectaglaze has been the leading designer of acoustic secondary glazing systems since 1966 and has been working on a Framework agreement with Crossrail and Network Rail since 2011 to provide sound insulation in line with statutory requirements.
Huge investment in rail infrastructure and station upgrades generates significant noise levels both from the construction works and day to day operations. Major stations are also an attractive location for Hotels and Offices. Intrusive noise is a real problem and failure to deal with it can lead to sleep loss, lapses in concentration and increased levels of stress that can affect general health. Noise needs to be carefully managed to ensure that it does not have an adverse impact on peoples living and working environments.
Noise Mitigation: Acoustically, windows are often the weakest point in a building with most single glazed windows reducing noise by just 25-30dB - less if they are ill fitting. Even modern double glazed windows only achieve 30-35dB. Set against potential external noise levels of 70-80dB, significant additional insulation is required to meet best practice guidelines from the World Health Organisation of 30dB for bedrooms or living rooms and 35dB for meeting rooms.
Secondary Glazing offers a very practical solution. A fully independent tailor made window system is set 100mm or more from the existing window and the sizeable air gap decouples the two panes of glass to reduce resonance. High performance frame seals will limit airborne sound. Noise reduction in the range 40-45dB is achievable using standard glazing materials and up to 50dB with heavier acoustic laminates.
Selectaglaze secondary glazing systems are designed for high performance and this is backed up by test data from Taywood laboratories in accordance with BS EN ISO 140-3:1995.
Besides acoustic benefits Secondary Glazing can also improve security and energy performance
Enhanced Security: Major stations form an important part of the National Infrastructure and security is a key consideration. Windows in critical locations need to be protected both against forced entry and the effects of blast. Selectaglaze has developed and tested a range of high security frames suitable for retrofitting. These have resisted physical attack up to level 3 of Loss Prevention Standard LPS1175 and blast to level EXV15 of standard ISO16933 (100Kg of TNT equivalent at a distance of 15M)
Energy Saving: Windows lose energy through draughts and by conduction of heat across the glass and frames. Bespoke secondary glazing with high performance seals will significantly reduce air leakage and the inclusion of low emissivity glass can cut heat loss by about 60% compared to traditional single glazed window frames. As a result the building will use less energy for heating and achieve a higher rated Energy Performance Certificate.
Selectaglaze has recently cooperated with English Heritage on a programme of research including the Bolsover Test House where a secondary window glazed with Pilkington’s Spacia sealed units recorded a centre of pane U-value of 0.8. The use of this technology, in conjunction with air tightness measures and mechanical ventilation using heat recovery, could allow a refurbished listed building to get close to EnerPHit standards.
Window Styles: Secondary glazing is available in a wide range of styles including horizontal sliding, balanced vertical sliding, hinged and fixed. The preferred frame material is aluminium, a strong versatile metal that can be extruded into complex shapes and readily formed to deal with the curved windows often found in traditional buildings. Framing sections are powder coated to provide a permanent finish, normally white but almost any colour can be accommodated.
Listed Buildings: Many station buildings are listed or have special architectural merit and the windows need to be retained. Purpose designed secondary glazing can be sympathetic to the character of a building and as a reversible adaptation will generally receive Listed Building Consent.
Professional delivery: As with all elements of upgrade or refurbishment a successful outcome needs careful up-front design and close project management. Selectaglaze’s Secondary windows are purpose made to precisely fit each window opening. Full off-site fabrication allows installation to be rapidly completed with minimal disruption to buildings in occupation. The use of lean processing methods and flexible programming will support the very tight programmes that clients often need.
The company works to consistently high quality standards and has been a Royal Warrant holder since 2004.
Advice and training: Selectaglaze offers a free technical advisory service and a RIBA approved CPD seminar entitled:“Understanding and Specifying Secondary Glazing”. This will be relevant to architects, designers and contractors working on refurbishment and up-grade schemes, particularly those involving traditional or listed buildings. Energy performance, environmental noise problems and enhanced security issues are all fully covered and a Q and A session allows for more detailed discussions.