17-4-2013 LECTURE N° 5 ES -E D U - Acoustical comfort - Lecture contributions Coordinator of the lecture: Pavla Dvořáková, Faculty of Civil Engineering, CTU in Prague, pavla.dvorakova@fsv.cvut.cz, http://tzb.fsv.cvut.cz/ ID • Contributors: • • Nathalie Geebelen, N.Geebelen@chri.nl Pavla Dvořáková, Faculty of Civil Engineering, CTU in Prague, pavla.dvorakova@fsv.cvut.cz, http://tzb.fsv.cvut.cz/ 2 1 17-4-2013 Sound -E D U Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations. Sinusoidal waves of various frequencies; the bottom waves have higher frequencies than those above. The horizontal axis represents time. ID ES 3 http://educypedia.karadimov.info/electronics/dataaudio.htm 4 2 17-4-2013 unwanted sound environmental pollutant a waste product undesired physiological or psychological effect 5 ES Bluyssen 2009 -E D • • • • U Noise Sources of noise ID Sources in a building • Sounds produced inside -from service equipment (elevators, sanitary installations, HVAC systems), from other users • Sound produced outside – traffic, .. Bluyssen 2009 6 3 17-4-2013 Sound Pressure Level Noise = unwanted sound Threshold of Hearing U Threshold of Pain Sound at 155 decibels can burn the skin. -E D Sound at 180 decibels can kill. http://www.abqenvironmentalst ory.org/city/energypollution/s5noise.html ES 7 Acoustical Comfort ID Room acoustical quality -> reverberation time -> undesirable echo’s and reflections Sound insulation between rooms -> air-borne sound insulation -> structure-borne sound insulation Background noise levels -> technical installations -> environmental noise 8 4 17-4-2013 Acoustical Comfort in relation to… 9 ES -E D U Room acoustical quality -> reverberation time <-> concrete core activation -> undesirable echo’s and reflections <-> room shapes Sound insulation between rooms -> air-borne sound insulation <-> circulation sound -> structure-borne sound insulation <-> floor constructions Background noise levels -> technical installations <-> location of technical rooms -> environmental noise <-> building site layout Room acoustical quality ID -> reverberation time The time necessary, after switching off the source, for the sound pressure level to drop 60 dB. 10 5 17-4-2013 Room acoustical quality -> reverberation time Sound absorbing space U Sound reflecting space Long reverberation time ES -E D Short reverberation time 11 Room acoustical quality -> reverberation time: target values Reverberation time Furnished room Office space Landscape office Classroom Music room Theatre Chamber music hall Opera Concerthall Church (organ music) T = ca. 0,5 s T = 0,5 – 0,7 s T = 0,7 – 0,9 s T = 0,6 – 0,8 s T = 0,8 – 1,2 s T = 0,9 – 1,3 s T = 1,2 – 1,5 s T = 1,2 – 1,6 s T = 1,7 – 2,3 s T = 1,5 – 2,5 s ID Type of room 12 6 17-4-2013 Room acoustical quality -> reverberation time in seconds T= 1/6 x (V/A) Room volume in m3 Total absorption in the room in m2 U The larger the room, the longer the reverberation time! 13 ES -E D The more absorbing materials present in the room, the shorter the reverberation time! Room acoustical quality ID -> total absorption in m2 Surface area in m2 of the material A = α1 x S1 + α2 x S2 + α3 x S3 + … Absorption coefficient of the material 0 < α < 1 totally reflecting totally absorbing An open window has an absorption coefficient α equal to 1 (all of the sound will disappear outside through the open window). If the surface area of the open window equals 1 m2, then the total absorption of this window is equal to A = 1 x 1 = 1 m2 14 7 17-4-2013 Room acoustical quality 15 ES -E D U -> sound absorbing materials = acoustically ‘soft + open’ materials or perforated materials with an acoustically ‘soft + open’ material behind the perforations Room acoustical quality ID -> sound absorbing materials = acoustically ‘soft + open’ materials or perforated materials with an acoustically ‘soft + open’ material behind the perforations [Source: Schallschutz + Raumakustik in der Praxis – Planungsbeispiele und konstruktive Lösungen, W. Fasold / E. Veres, Verlag für Bauwesen – Berlin, 1998] 16 8 17-4-2013 Room acoustical quality -> calculation of reverberation time 3.0m 3.0m S [m2] 0<α<1 α x S [m2] Ceiling Floor Window Door Walls 9 9 1 2 33 0,79 0,04 0,03 0,08 0,02 7,11 0,36 0,03 0,16 0,66 Total A [m2] 8,32 U 3.0m Surface 17 ES -E D A = a1 x S1 + a2 x S2 + a3 x S3+…. [m2] T= 1/6 x (V/A) = 0,167 x (27/8,32) = 0,54 s Room acoustical quality ID -> problem: classroom 15 x 8 x 3 m3, door 2 m2, window 12 m2 target value reverberation time T = 0,7 seconds Surface 0<α<1 Floor Window Door Walls 0,04 0,03 0,08 0,02 [Source: Schallschutz + Raumakustik in der Praxis – Planungsbeispiele und konstruktive Lösungen, W. Fasold / E. Veres, Verlag für Bauwesen – Berlin, 1998] Which absorption coefficient is necessary for the ceiling to achieve a reverberation time equal to 0,7 seconds? 18 9 17-4-2013 Room acoustical quality -> solution: T= 1/6 x (V/A) A = 1/6 x (V/T) = 0,167 x (360/0,7) = 86 m2 S [m2] 0<α<1 α x S [m2] Ceiling Floor Window Door Walls 120 120 12 2 124 ? 0,04 0,03 0,08 0,02 ? 4,8 0,36 0,16 2,48 ? + 7,8 -E D Total A [m2] U Surface α = A/S = 78,2/120 = 0,65 19 ES 86 – 7,8 = 78,2 m2 Room acoustical quality ID -> Regular office room with concrete core activition target value reverberation time T < 0,8 s Solution: Add sound absorbing materials to the upper part of the walls 20 10 17-4-2013 Room acoustical quality -> Landscape office with concrete core activition target value reverberation time T < 0,5 s (furnished room) upper part of the walls = not sufficient 21 ES -E D Ceiling islands or baffles U Alternative solutions Room acoustical quality ID -> undesirable echo’s and reflections -> reflectogram! 22 11 17-4-2013 Room acoustical quality -> undesirable echo’s and reflections -> reflectogram! - direct sound: source receiver + pseudo-direct sound: reflections within 20 ms => speech intelligibility and localisation of the source - reverberation: after 100 ms positive effect speech intelligibilty negative effect speech intelligibilty positive effect music negative effect speech intelligibilty effect music depends on music type U - reflections: within 50 ms 50 ms – 80 ms -E D - flutterecho: back-to-back refelctions on opposite (parallel) acoustically hard walls - focussing: cocentrated sound through bundling of reflected sound rays ES 23 Room acoustical quality ID -> undesirable echo’s and reflections -> effected by room shape and location of sound absorbing materials 24 12 17-4-2013 Sound insulation between rooms structure-borne sound insulation 25 ES -E D U air-borne sound insulation Sound insulation between rooms ID -> air-borne sound insulation Sound transmission -1 direct -2 flanking -3 circulation 26 13 17-4-2013 Sound insulation between rooms 27 ES -E D U -> circulation sound = sound that reaches the destination room through an adjacent space or room, for example a plenum Solution? Sound barriers Sound insulation between rooms ID -> flanking sound = sound that reaches the destination room through adjacent constructions 28 14 17-4-2013 Sound insulation between rooms 29 ES -E D U -> sound leaks, for example with pore seam sealing, through cable trays, duct transits, etc. Sound insulation between rooms -> structure-borne sound insulation ID • sliding chairs • walking sounds • falling objects •… Direct <<excitation>> of the building Lots of energy injected into the buidling structure! FLOOR MASS = UNSUFFICIENT 30 15 17-4-2013 Sound insulation between rooms 31 ES -E D U -> improving structure-borne sound insulation floating floors structures! Sound insulation between rooms ID -> floating floors structures = very sensitive to construction details on site - levelling ducts - border strips - flexibel layer - covering foil 32 16 17-4-2013 Background noise levels 33 ES -E D U -> Installation noise = background noise coming from the operation of all the necessary technical installations in a building such as airconditioning units, elevators, sanitary installations, etc. Background noise levels -> technical installations ID Energy efficiency / Comfort Ventilation system (incl. cooling) Technical installations larger and larger Project enough technical rooms Where?? 34 17 17-4-2013 Background noise levels -> building design ES -E D U • Technical rooms not directly adjacent to work or living spaces • Installations not on the roof, noise disturbance for the environment • Sanitary blocks, elevators, traffic zones not directly adjacent to work or living spaces • Installation noise can also be useful for preserving speech privacy in a landscape office 35 Background noise levels -> building design ID Office or living space Office or Office or living space living space Office or Office or Office or living space living space living space Office or living space Target value background noise max. 30 à 35 dB(A) [Source: Bouwakoestiek, G. Vermeir, Uitgeverij Acco Leuven, 1999] Target value background noise max. 30 à 35 dB(A) 36 18 17-4-2013 Noise radiation -> air-conditioning unit on roof top: - 3 dB with doubling of the distance Sound pressure level 80 à 100 dB(A) 40 à 60 dB(A) U Sound power level -E D 30 m Mesures necessary!! Enclosures, silencers, … ES 37 Background noise levels ID -> Environmental noise = background noise coming from sound sources outside such as traffic (cars, trains, airplanes), industry, bars, etc. [Source: Bouwakoestiek, G. Vermeir, Uitgeverij Acco Leuven, 1999] 38 19 17-4-2013 Background noise levels 39 ES -E D U -> High environmental noise levels solutions through building site layout Background noise levels ID -> High environmental noise levels solutions through building design 40 20 17-4-2013 Background noise levels 41 ES -E D U -> High environmental noise levels solutions through facade design Background noise levels ID -> Facade sound insulation = composed sound insulation 42 21 17-4-2013 Background noise levels 43 ES -E D U -> Weak link in facade sound insulation = seam sealing - ‘deaf’ facade = completely ‘closed’ facade -> windows cannot be opened -> to be used with high sound pressure levels from environmental noise - ventilation through facade openings not possible Background noise levels ID -> Weak link in facade sound insulation = ventilation openings - mechanical balanced ventilation system - ventilation through sound muffled ventilation unit sound absorbing material 44 22 17-4-2013 Standards on acoustics • • • • 45 ES • U • EN 12354 Building acoustics: estimation of acoustic performance of buildings from the performance of elements EN ISO 14257 Acoustics: measurements and parametric description of spatial sound distribution curves in workrooms for evaluating acoustical performance EN ISO 140 Acoustics. Measurement of sound insulation in buildings and of building elements EN ISO 10052 Acoustics: field measurement of airborne and impact sound insulation and of service equipment noise; survey method ISO 9921 Ergonomics. Assesment of speech comunication EN ISO 18233 Acoustics: application of new measurement methods in building and room acoustics ISO 6897, ISO 2631-1, ISO 2631-2 -E D • Literature L. CREMER, M. HECKL, E. UNGAR, Structure-Borne Sound, Springer Verlag, 1973 ID • • • • • • • • L. CREMER, H. MÜLLER, T. SCHULTZ, Principles and Applications of Room Acoustics, Volume 1, Volume 2, Applied Science Publishers, 1982 L.L. Beranek (ed.), Noise and vibration control, Institute of Noise Control Engineering, 1988 W. Fasold, H. Winkler, Bau- und raumakustik, Verlag für Bauwesen, VEB, Berlin, 1987 Bluyssen Philomena M.: The Indoor Environment Handbook, How to Make Buildings Healthy and Comfortable, Earthscan Ltd (United Kingdom), 2009, ISBN-13: 9781844077878 http://educypedia.karadimov.info/electronics/dataaudio.htm http://www.abqenvironmentalstory.org/city/energy-pollution/s5noise.html http://www.freewebs.com/soundwaves-/introduction.htm 46 23