The benefits of secondary glazing!

Clients may want the convenience of a hotel which is close to transport networks and to the pubs, clubs and theatres of city centres, but they also want a good night’s sleep in a warm and comfortable room. It is essential, therefore, to deal with local noise problems and also ensure that heating costs don’t get out of hand.

Buildings account for 40% of the UK’s total carbon emissions and a survey undertaken by The Carbon Trust has shown that hotels use nearly half their energy supplies for heating.This is both expensive and wasteful and with growing emphasis on climate change, building owners everywhere will need to consider ways of reducing usage. A current benchmark for a building’s energy conservation performance is Part L of the Building Regulations, but this only applies to new buildings and those undergoing major reconstruction or change of use. However, it is possible to raise the energy efficiency of existing buildings to meet the standard without affecting occupancy. Payback is made through reduced energy bills, the value of an enhanced Energy Performance Certificate and a visibly proactive policy on the Environment. With sustainability and green issues becoming more important to many clients, this could be an important factor in their choice of hotel.

Single glazed windows are found in many existing and historic buildings and are a major factor in energy loss, both because glass is a poor insulator, and because the windows can be ill fitting and draughty. A simple and cost effective solution is to introduce secondary glazing. This is not a new concept, since some 19th century houses were constructed with a second double hung sash window designed to provide better insulation. Today’s high performance secondary glazing involves a fully independent window system fitted to the room side of the existing window, which remains unaltered and in its original state. It is purpose made and discretely fitted with minimal disruption to the day to day running of a business and the building’s occupants. It is recommended by Heritage bodies for use in Listed buildings and those in conservation areas, but is equally applicable to almost any building type.

Secondary glazing traps an insulating layer of air between the windows and efficient seals will exclude draughts over the whole frame. The use of low emissivity glass will allow the U-value, a measure of the rate of heat loss through the window, to fall below 2.0 from typically 5.7 in a single glazed window, a figure that is better than the requirements of Part L. Noise is also a major problem, whether it originates from traffic flow, aircraft, trains, music from a nightclub or pub, or simply the wind whipping round the headland. Not only is unwanted noise intensely aggravating and disturbing, but it is a major source of stress and can ruin a good night’s sleep.

Disturbance levels will depend on the type of noise, the loudness, duration, the time of day and the ability to control it. Noise levels need to be carefully managed to provide an acceptable living and working environment, whether it is keeping noise out or noise in.

Sound is measured as a pressure and is expressed in decibels. The scale is logarithmic and an increase in Sound Pressure Level (SPL) of 10dB approximates to a doubling of loudness, whereas a change of 3dB is just about noticeable. Heavy street traffic will register 80dB and a pop concert 100dB, whereas a reasonable internal level for a bedroom at night is 30-35dB and 35-40dB for a day time meeting room.

Most existing single glazed windows will reduce noise levels by 25-30dB and even modern double glazed windows will normally only achieve 30-35dB, often not enough to create a comfortable environment. Secondary windows can reduce noise levels by  5-50dB and really make a difference. The internal window is set with a minimum air gap of 100mm and this decouples the two glass panes and reduces noise transmission. The greater the cavity the better the  dampening effect. Royal Warrant holder Selectaglaze Ltd, offers a wide choice of styles including horizontal sliding, balanced vertical sliding, hinged and fixed. The framing sections are aluminium, a strong versatile material that can be extruded into complex shapes and readily formed to deal with the curved windows found in traditional buildings. The sections are powder coated to provide a permanent finish in almost any colour.

Systems are rigorously tested and assessed for performance. Acoustic tests at the Taywood Laboratories in accordance with BS EN ISO 140-3:1995 (Laboratory measurement of airborne sound insulation of building elements) demonstrates that 45-50dB noise reduction is achievable and even higher levels if the external window is also enhanced. Thermal insulation is assessed through ‘The Centre for Window Cladding and Technology’.

Using a hard coat, low emissivity glass, the Uvalue of the combination window falls to between 1.8 and 1.95 and this further reduces to 1.6-1.7 if the external window is double glazed.

Secondary windows are unobtrusive and can be designed to be as sympathetic as possible to the character of the building.The windows arrive fully glazed and can be fitted with minimum interference to the hotel operation and can even be installed during handover periods if a hotel is in full occupancy, ensuring no loss of revenue.

Article courtesy of Selectaglaze Ltd.
More information and literature is available on: 01727 837271
e-mail: enquiries@selectaglaze.co.uk or visit: www.selectaglaze.co.uk