ACOUSTIC VENTILATION SYSTEMS FOR NEW HOUSING

Transcription

1 CI/SfB (57) (P2) Uniclass L7513:N3721 March 2002 SYSTEMS FOR NEW HOUSING

2 ... VENTILATION AND NOISE The noise problem Noise pollution is becoming an increasing problem as transport systems develop and there are fewer greenfield sites available for newbuild housing. The need for ventilation Ventilation is essential, and required by building regulations, but it can provide paths for noise to penetrate. Noise levels and planning In PPG24 the DETR recommends that planning authorities considering planning applications for new housing take into account the noise exposure category (NEC) of the site as shown in the table below. Protection against noise may be made a condition of planning permission. Passivent solutions In noisy locations, acoustically treated ventilators and systems will often enable planning conditions to be met, making developments possible that would otherwise be refused planning permission. Passivent systems can provide the solutions to suit the needs of noisy sites. Noise exposure category (from PPG24) Comments A Noise need not be considered as a determining factor in granting planning permission, although the noise level at the high end of the category should not be regarded as a desirable level. Housing at the high end of A may require acoustically treated wall or window vents in habitable rooms. B Noise should be taken into account when determining planning applications and, where appropriate, conditions imposed to ensure an adequate level of protection against noise. In B it would normally be recommended that ventilation is designed to avoid the need to open windows. In the past, treatment has meant the use of large unsightly acoustic boxes for input and extract, drawing attention to the problem of noise. PPG24 now recommends wholehouse systems as an alternative, because these operate continuously, unlike input/extract acoustic boxes which are normally switched off. C Planning permission should not normally be granted. Where it is considered that permission should be given, for example because there are no alternative quieter sites available, conditions should be imposed to ensure a commensurate level of protection against noise. In C further acoustic treatment to ventilation will be required to avoid the need to open windows. D Planning permission should normally be refused.

3 ... PASSIVENT SOLUTIONS Passivent PSV (passive stack ventilation) and AV (assisted ventilation) systems with acoustic treatment are an effective, energyefficient means of ventilation. This is supported by BRE Digest 338 which states that It may be more economical to provide mechanical ventilation on the basis of the whole building, rather than room by room. Passivent acoustic systems provide wholehouse ventilation meeting the Building Regulations Approved Document F1 requirements for both background and extract ventilation. Passivent systems are BBA Certificated to meet Building Regulations with inlets as small as 4000mm 2 per habitable room, compared with the Approved Document F1 requirement for 8000mm 2 (equivalent to a hole in the wall over 100mm in diameter allowing noise in). Case studies demonstrating a proven track record are given in separate leaflets. More detailed information on Passivent wholehouse systems is given in a separate brochure. Passivent Limited offer a free, comprehensive design service to satisfy DETR PPG24 for noise control and Approved Document F1 for ventilation. Passivent Solutions Passivent PSV: for Categories A - B Passivent PSV (passive stack ventilation) is a nonelectrical stack-effect system which provides continuous gentle extraction from kitchens and bathrooms. It is preferable to wall fans because ducted extraction through the roof means no noise from outside and no fan noise. Acoustically treated wall or window vents in habitable rooms replace the extracted air. Automatic control related to room humidity is also possible. Certificate No. 96/3273 Passivent AV: for Categories B - C Passivent AV (assisted ventilation) whole-house systems provide a discreet alternative to acoustic boxes; in many cases there is no visible acoustic treatment. This is a fan-assisted system developed from PSV, and typically includes: - Acoustically treated wall or window inlets in habitable rooms - A ducted extraction system from the kitchen and bathroom to a roof terminal, via a single low-energy continuously-running fan in the roof space. Certificate No. 96/3273 Passivent AV+: for C Passivent AV+ systems are similar to Passivent AV with additional acoustic treatment, possibly including: - Acoustic wall inlets in wet rooms (kitchen and bathroom) - Extracts in habitable rooms adjacent to noise source - Acoustically treated ductwork with boosted extraction. Passivent Limited offer a free comprehensive design service...

4 ... PASSIVENT COMPONENTS... General Systems comprise air inlets, room extracts, ducting and roof terminals, plus fans for AV systems. Sound insulation is achieved by the use of acoustic inlets, and if necessary acoustic ducting. Apart from fans, units do not require any power supply. Further information is given in other Passivent literature. Note: product codes such as 80dB refer to dimensions not sound reduction. Sound insulation data Weighted normalised level differences (D n,e,w ) for components are given in decibels (db), based on extensive testing to BS EN 20140: Part 10: 1992 (ISO ). BBA Certificate Agrément Certificate No 96/3273 covers Passivent PSV and AV systems. Fresh 90dB wall inlet Ventilation area 6000mm 2 controllable; optional 300mm 2 trickle. Sound reduction 43dB across 300mm wall thickness; can be increased to over 50dB with external cowl. Fresh 80dB wall inlet Ventilation area 4000mm 2 controllable; optional trickle. Sound reduction 50dB across 300mm wall thickness. Fresh 100dB wall inlet Ventilation area 6000mm 2 controllable; optional trickle. Sound reduction 46dB across 300mm wall thickness. Certificate No. 96/3273 Fresh 99HdB wall inlet Ventilation area 6000mm 2, automatically controlled by room humidity. Sound reduction 46dB across 300mm wall thickness; can be increased to over 50dB with external cowl. A101 window inlet/ TVAG4 acoustic grille Ventilation area 4000mm 2, automatically controlled by room humidity. Sound reduction increased to 48dB with TVAG4 external grille. TVOVN overhead window inlet Ventilation area 3200mm 2 per 1.2m length. Sound reduction 34dB. Roof terminals Ridge terminals or tile/slate terminals do not require acoustic treatment. Ducting Performance data for acoustic ducting can be provided on request. Air extracts Extract air from kitchens and bathrooms. Acoustic treatment not necessary. A151 and A160 Acoustic slim fan For AV systems, mounted in the roof space or an enclosed cupboard. Independent tests have shown that the fans are not generally audible in an adjoining room. More information available on request.

5 ... TECHNICAL BACKGROUND The following is given as background information only. Specifiers and designers are advised to seek specialist guidance from Passivent Limited or an acoustic consultant. Acoustic requirement There are no building regulation requirements for sound insulation against noise from outside. Internal noise level criteria are given in the following documents: PPG24 Planning policy guidance: Planning and noise (DETR) This defines four noise exposure categories (NECs) for new dwellings. Planning authorities are recommended to take into account the noise exposure category of a site (see table opposite). Definitions of the categories are complex and depend on standardised measurement of noise from road, rail and air traffic, or from mixed sources, by day and night. PPG24 implies that the maximum internal noise levels (from external transport sources) are 45 LAeq for living rooms in daytime (18 hours), and 35 LAeq for bedrooms at night (6 hours). BS 8233: 1987 Sound insulation and noise reduction for buildings Section 3, 8.1 (design criteria for dwellings) states: Recommended maxima for steady intrusive noises (see BRE Digest 266) are as follows. (a) bedrooms LAeq,T = 30dB to 40dB; (b) living areas (for conversation and listening to radio and television): LAeq,T = 40dB to 45dB. Windows and other construction A partially open window provides a noise reduction (sound level difference) from outside to inside of about 10 to 15dB. Thus no special treatment is necessary if the external noise levels are no more than 10 to 15dB higher than the internal noise level criteria. Where external noise levels exceed these values, openable windows are not acceptable and so there is a need to provide alternative acoustically-attenuated ventilation. A modern sealed window with 6mm single glazing will, when closed, provide sound insulation of about 26dB(A). When assessing the need for acoustic ventilation in noisy areas it is essential to ensure that the building fabric (walls, roof and windows) also provides adequate sound insulation. Fan noise With fan-assisted ventilation systems it is important that the fan itself does not add to internal noise. In Passivent AV systems the fan is located in the roof space or a cupboard rather than in the room itself. Duct noise control Extract ducts may need to be acoustically treated to prevent noise entering habitable rooms, especially in noisy areas, and to control noise transfer between separate dwellings served by common ductwork. Ventilation requirements Houses are required to have adequate means of ventilation. Approved Document F1 defines three types: - Rapid ventilation eg by opening windows, in all rooms - Background ventilation by wall or window ventilators in all rooms - Extract ventilation by PSV (passive stack ventilation) or fans - in wet rooms. Background ventilation required for domestic buildings: - Habitable room (living rooms, bedrooms): 8000mm 2 - Kitchen, utility room, bathroom ( wet rooms): 4000mm 2 - Separate sanitary accommodation: 4000mm 2 Alternative 1: average of 6000mm 2 per room with a minimum of 4000mm 2 in each room. Alternative 2: the ventilation system can be third-party assessed. Passivent PSV and AV systems are BBA certificated.

6 ... FURTHER INFORMATION References PPG24 Planning policy guidance: Planning and noise (DETR) BS 8233: 1987 Sound insulation and noise reduction for buildings BS EN : 1992 Acoustics. Measurement of sound insulation in buildings and of building elements. Laboratory measurement of airborne sound insulation of small building elements (= ISO ) BRE Digest Insulation against external noise Building Regulations Approved Document F1 (1995 as amended 2000) Means of ventilation Passivent products Passivent product ranges also include: Passivent natural and energy-efficient ventilation systems for domestic buildings Passivent Tricklevents Passivent Fresh wall ventilators Passivent natural ventilation systems - commercial Passivent Aircool wall ventilators Passivent Airscoop roof-mounted ventilators Passivent high capacity ventilation terminals for commercial buildings Separate literature is available for these on request. PASSIVENT LIMITED 2 Brooklands Road, Sale, Cheshire M33 3SS Tel: Fax: info@passivent.com Web: Passivent Limited maintains a policy of continuous development and reserves the right to amend product specifications without notice. A member of the Building Product Design Group Produced by Ted Hastings/Rackley Design......