EFA BASELINE DESIGNS ACOUSTICS STRATEGY. Acoustic Design of Schools

Transcription

1 EFA BASELINE DESIGNS ACOUSTICS STRATEGY Acoustic Design of Schools

2 Contents 1. Introduction The Baselinee Design Solutions Control of reverberation Classbases Dining/atrium and multi-storey circulation Main hall Sports halls (secondary schools) ) Single storey circulation space/corridors Environmental Noise and Ventilation Sound Insulation Rain Noise Alternative Performancee Standardss (APS) and Refurbishment Baseline Secondary school (superblock) section through dining hall... 7 Baseline Secondary school (finger r block) section through teachingg spaces Page 2 of 8

3 1. Introduction The baselinee designs are in line withh Acoustic Design of Schools Performance Standards for Schools, to be published by EFA andd included as part of the Output Specification for the Priority Schools Building Programme (PSBP). A panel of industry experts have been involved in the preparation of this document which iss essentially a revision of Building Bulletin (BB) 93, with amendments made to reflect changes in school design since the early 2000s (e.g. trends in open plan, refurbishment) and the experience of the panel in relation to performance targets. Acoustic Design of Schools Performance Standards for Schools is to supersede Section 1 of Building Bulletin 93 (BB93). Section 2 of the document will bee published at a later date with the aim of demonstrating good practice in thee implementation of the PerformanceP e Standards. This report is to be read in conjunction with other related text on the EFA website which sets out Key Principals of acoustic design, relating to the Baseline Designs. Page 3 of 8

4 2. The Baselinee Design Solutions 2.1 Control of reverberation The Baseline designs demonstrate methods of reverberation control that work in harmony with other environmental control factors (e.g. daylighting, ventilation, thermal mass etc.). Approaches vary depending on the type of spaces. Types T of spaces are discussed below Classbases Reverberation in classbases is controlled predominantly by absorptive panels suspended horizontally from the soffit, interspersed between light fittings; panels are highly acoustically efficient (Class A) andd light reflective. In orderr to not compromise the thermal benefit of the exposed soffit, thee area of suspended absorbers is approximately 40% of the floor area. a Depending on the size of room, floor finish and age of pupils being taught, these absorbers are supplemented by Class A wall panels.. Furniture acts constructively to diffuse the sound that could otherwisee reflect between parallel hard surfaces Dining/ /atrium andd multi-storey circulation Reverberation in these large-volume, high occupancy, spaces is controlled by a combination of perforated roof liner (Class C or better), absorbent finishes to the underside of walkways (Class A) and significant coveragee of wall panels (absorption Class dependant on coverage area) Main hall Unlike many other spaces, reverberation needs to be controlled to achieve a minimum, in additionn to maximum, levels. This is to facilitate speech and support a variety of activities. Reverberation is controlled by an absorbent liner (Class C or better), absorbent panels (Class( C or better) to the rear wall and absorbent panels (Class C or better) to side walls. The coverage and type of panels/materialss will vary according to their type, coverage and location. It may be advantageous to allow for a reflectivee section of ceiling towards the front and centree of the soffitt or ceiling in order to facilitate reflection off speech to the rear section, althoughh this may not always be practicable. Page 4 of 8

5 Sports halls (secondary schools) It is important to provide both absorption andd diffusion, not just at high level but in the listener plane. Due to the activities carried out in these spaces, all materials must be highly durable. Absorption is provided by means of a perforated roof liner (Class C or better) and fair-faced, Class D absorptive blockwork fromm finished floor level to at least 3 m above. The fair-faced blockworkk and profiless of the roof line also act to provide significant amounts of diffusion Single storey circulation space/corridors Corridors and similar spaces willl be installed with demountable ceilings having Class C sound absorption or better, to control sound andd provide good access to services. 2.2 Environmental Noise and Ventilation Double sided ventilation is used in the secondary school classrooms in order to maintain acceptable concentrations off carbon dioxide in spaces, whereverr possible. Air inlets are in the t form of opening windows or louvres in the external façade, with highventilation. level attenuated ventilators or chimneys to corridors and a atria, allowing stack Windows and non-acoustic louvres can be used where the external noise level does not exceed the required Indoor Ambient Noise Level by more m than 133 db(a); if external noise levels are higher, then attenuated forms of ventilationn would be required. Ventilators to corridors are attenuated such that they meet the requirements of the Outputt Specification and minimise cross-talk attenuation. Where spaces are mechanically ventilated then appropriate controls of noise level and cross-talk will be required to maintain Indoor Ambient Noise Levels and sound insulation targets. 2.3 Sound Insulation Sound insulationn between classroom and office areass is providedd by metal stud partitioning systems with gypsum board lining and insulation as appropriate a to meet performance targets. Where glazed screens are used then these meet composite performance requirements of the partition they are installed within. Similarly, door sets are acoustically rated to either Page 5 of 8

6 meet single figure criteria forr the type of room or composite values of the overall partition they are installed within. Floors are of concrete construction to facilitate passive cooling viaa thermal mass. This provides levels of vertical sound insulation appropriate for most adjacencies, requiring additional attenuation in the form of floating floors or mass barrierr ceilings where adjacencies demand additional attenuation. Impact sound s insulation is controlled by floor finishes. 2.4 Rain Noise Concrete roofs control noisee generated by heavy rainn on roofs in many areas. Lightweigh roofs incorporate compressed mineral fibre insulationn under the top liner sheet in order to suppress impact-generated noise. 2.5 Alternative Performan ce Standards (APS) and Refurbishment Where it is not possible to comply with the new-build criteria of the Output Specification for operational or health & safety reasons, and this non-compliance is sanctioned by the EFA and their Technical Advisors, then a relaxation in performance targets is permissible, but only to the extent set out in performance tables for refurbishment t standards. Page 6 of 8

7 3. Baseline Secondary school (superblock) section through dining halll Sound absorption to soffit Absorbent panels to walls Sound absorption to underside of balconies Acoustically rated doors to teaching spaces Page 7 of 8

8 4. Baseline Secondary school (finger block) section through teaching spaces Sound absorption to circulation space Concrete roof provides rain noise control Suspended Class A absorbers Class A absorbent wall panels Attenuated high level ventilators either side of glazed panel Page 8 of 8

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