Saint-Gobain Insulation acoustical comfort classes

Transcription

1 19 th INTERNATIONAL CONGRESS ON ACOUSTICS MADRID, 2-7 SEPTEMBER 2007 Saint-Gobain Insulation acoustical comfort classes PACS: n Andrew Koster 1 1 Saint-Gobain Insulation, Parallelweg AH Etten-Leur The Netherlands Andrew.Koster@Saint-Gobain.com ABSTRACT Based on the research project "Sound Insulation in Housing Construction" carried out by professor J.Lang, R.Pierrard and W.Schönbäck (TU Wien, Fachbereich Finanzwissenschaft und Infrastrukturpolitik) Saint-Gobain Insulation defined acoustical comfort classes for airborne and structure borne sound insulation inside and between dwellings. This article will describe this study, the European investigation of people annoyed by airborne and structure borne sound, different one figure indexes used. Based on this comfort classes light weight solutions will be described. Finally the extra costs by enhanced sound insulation will be described. INTRODUCTION The compilation of results obtained from environmental surveys in different European countries shows that the second most frequent source of noise pollution are one's neighbours, after road traffic noise which causes the majority of noise complaints. In Austria, for instance, a survey conducted every 3 years as part of the micro census found out that neighbourhood noise - after traffic noise - was the second most frequently indicated cause of strong to very strong noise disturbance until the mid-1980s. As a result of improved sound insulation in housing construction and the strict observance of standard requirements in subsidized housing construction, neighbourly noise is now perceived to be at nearly the same level as industrial noise. It is, however, slightly exceeded by "other sources of noise" (e.g. leisure facilities). In 2003, 7.7 % of the respondents who felt strongly or even extremely disturbed by noise claimed neighbourhood noise was the cause of the disturbance. Table 1: Noise annoyance in Austrian dwellings percentage annoyed In all slight *) *) medium 9.8 strongly *) very 6.2 strongly *) *) Until 1988 the evaluations were performed referring to the households, while the results were evaluated referring to households until 1994; from 1994 referring to people; for the year 1994 both evaluations are stated: the upper number refers to households, the lower number to people.

2 In Germany it was deduced from an inquiry about the experienced noise annoyance that about 17.3 % are annoyed moderately, strongly or extremely by noise from the neighbours. In the U.K. in 1999/2000, a National Survey of Attitudes to Environmental Noise was performed with a detailed questionnaire. 84 % reported hearing road traffic noise, 81 % hearing noise from their neighbours or other people nearby, 58 % hearing the neighbours inside their homes; 40 % reported being annoyed or bothered by road traffic noise, 37 % by the noise of the neighbours or other people nearby. In the Netherlands an investigation found that sound originating from the neighboring flat can be heard in about 75 % of apartments, and heard every day in 40 %. In about 1/3 of all households this sound is found to be annoying, and for 13 % very annoying. In the Netherlands a comprehensive study has been carried out (Gerretsen, 2001) for the appropriate unit to describe sound insulation and the requirements for 5 quality classes. The requirements were deduced from an emission level of 70 db(a) for neighbours radio on regularly loud moments and the difference of 12 db for speech and music, which gives 82 db, and an indoor reference sound level of 25 db(a). That results in a required sound insulation of DnT,w + C = 57 db; the comparison with the results from several social surveys with respect to sound in dwellings lead to the use of 5 classes covering the range from a just acceptable acoustic climate for existing situations (k=5) till the maximum comfort which seems to be practically achievable (k=1). In a study in panel-block-buildings in Lithuania, Slovakia and Eastern Germany it was found that in the investigated buildings 65 %, 40 % und 36 % respectively complained of noise, the primary source of which was noise from neighbours (talking, music, DIY activities and TV). As a result of a representative opinion poll among the population of Switzerland on the perception of and affectedness by noise, the following results were sampled. In response to a general question on the importance of the noise problem from a general point of view (Switzerland as a whole) and for the individual in particular, a ranking was made on a scale from 1 to 6 (1 = does not affect at all, 6 = strongly affects). According to the poll, road-traffic noise ranked highest with 4.2 (general view) and 3 (personal view) among the respondents. Neighbourhood noise ranked distinctly lower with 2.5 and 2 respectively. People dissatisfied with their homes assess the environmental impact of neighbourhood noise in Switzerland clearly higher (3.1) than those satisfied with their homes (2.4). Sound insulation one figure indexes in Europe The survey of the sound insulation requirements for residential housing in European countries conducted by Rasmussen 2 shows that different quantities are used to define the requirements (apparent sound reduction index, normalized sound level difference, standardized sound level difference with or without spectrum adaptation term for different frequency ranges, normalized impact sound pressure level, standardized impact sound pressure level with or without spectrum adaptation term for different frequency ranges) and the differences in the requirements in the various countries are very great up to 10 db (a difference of 10 db means about double loudness of the noise). 2

3 Table 1: Overview airborne sound insulation requirements in 24 European countries COMFORT CLASSES SAINT-GOBAIN ISOVER A calculation to prove which sound levels are caused in the neighbouring flat with different sound insulation by different activities (conversation between 6 people with normal loudness and animated conversation with laughter, and music played with a single instrument or with 6 instruments) shows that the sound insulation required in the existing standards does not make the neighbours activities inaudible at all. In several European countries, therefore, classes for enhanced sound insulation besides the minimum requirements dictated by building regulations have been defined in the last few years; these are based mainly on the standardized sound level difference plus spectrum adaptation term D nt,w+c (also written D nt,a ); in many cases the importance of the low frequency range (C ) is pointed out and partly especially in the higher sound insulation classes used in the requirements. In several countries specifications of the classes are given in the form of how many persons feel annoyed by the neighbours noise and how many are satisfied with the sound insulation. The impact sound insulation is mainly described by the normalized impact sound pressure level, partly with the spectrum adaptation term CI, whereby especially for the higher classes the low frequency range is also considered by CI, Several specifications exist on the correlation of subjective satisfaction and required impact sound insulation. Requirements for airborne and impact sound insulation within a flat (or a single-family house) exist only in some countries and only for the higher sound insulation classes. 3

4 In all considered countries sound insulation is planned on the basis of EN and -2; in many countries, calculation programs exist for the determination of the sound insulation in the planning state and data have been published as a basis for the planning. Measurements of the sound insulation in the finished building are partly scheduled for the classification (ascertaining the acoustic class of a building or a space). Based on calculations of the audibility of living activities on the one hand and on sound insulation classes in different countries on the other, the following requirements for airborne and impact sound insulation for 4 sound insulation classes are proposed. Table 3: Acoustic comfort classes Saint-Gobain Isover Class Music Comfort Enhanced *) Standard Airborne sound insulation between flats D nt,w +C (db) Airborne sound insulation between the rooms within a flat (without doors), also incl. one-family houses D nt,w +C (db) Impact sound insulation between flats L nt,w + C ***) I, (db) Impact sound insulation within a flat, also incl. one-family houses L nt,w + C ***) I, (db) 68 (C ) **) *) minimum requirements for terraced houses **) if requested ***) for a transitional period L nt,w + C I, values decreased by 2 db EXAMPLES OF LIGHT WEIGHT CONSTRUCTIONS In the last few decades, a growing number of multi-storey apartment houses have been built in Austria using timber constructions. When measuring the sound insulation of these buildings, it was found that with proper workmanship (particularly for the wall and floor connections) a high level of sound insulation can be achieved. For instance, when measuring the sound insulation in a multi-family house where the walls and floors had been constructed according to figure 1,2 & 3, the following weighted standardized sound level differences were found: D nt,w = 69, 64 und 60 db between adjacent rooms and 56 db between rooms located on top of each other. Figure 1 Connection between wall separating flats and floor (vertical section) 4

5 Figure 2: Connection between outer wall and wall separating flats (horizontal section) Figure 3: Connection between outer wall and floor (vertical section) Also with wooden constructions it is necessary to consider the sound insulation of the separating and flanking elements and their junctions. ÖNORM B and EN do not provide any information on how to calculate the standardized sound level difference for buildings in lightweight construction. In a comprehensive study, including the calculation and measurement of sound insulation in several residential buildings with timber construction, a calculation method was used 4. Based on the comparison of calculated and measured results, it was found to be suitable. This method makes use of the weighted sound reduction index of the separating and flanking elements. For flanking sound transmission, it uses the values for the weighted normalized flanking level difference according to DIN 4109, supplement 1, or a value of D n,t,w = 75 db when the flanking elements are completely interrupted by the separating element. At the weighted sound reduction indices for numerous types of wall and floor constructions have been compiled. They show that a very high sound insulation can be achieved. In addition, this website provides illustrated examples of suitable structural connections between floor and wall elements. The detailed calculations presented in the above-mentioned report (Scholl et al., 2004) also give insight into which sound insulation can be achieved and how the flanking elements influence the sound insulation. The standardized sound level difference is influenced by the area of the partition and the volume of the receiving room at each of the measuring positions and thus the comparison is distorted. The converted value for the standardized sound level difference is given in parentheses by the measured value of the apparent sound reduction index. The results show that high-quality sound insulation can be achieved in the wooden dwellings. 5

6 When comparing the sound insulation for the different versions of adjacent rooms one can see that the connection between the partition and outer wall has an important influence. With a total separation of outer wall and partition at the junction, an apparent sound reduction index of 60 db is achieved, and only 56 db if there is no total separation. The separation can be substituted by a shield (e.g. lining from plaster board) on the inner side of the outer wall, which is interrupted by the partition. The comparison of the results of the measurements of the sound insulation between rooms one above the other shows also the influence of the outer wall. Even with the better sound insulation of the separating floor, the sound insulation achieved is determined by the flanking outer wall. The construction with an inner shielding on the outer wall is clearly advantageous. Costs Acoustic comfort classes Various studies have put the expenses incurred by improved sound insulation at between 1 and 7% of the total construction costs. Calculations for a sample of massive constructions in the federal provinces of Upper Austria and Styria produced no significant correlation between the standard of sound insulation achieved and total construction costs. From this it can be deduced that other features have a far greater impact on construction costs than improved sound insulation, a result which is supported by other studies. At the end of the day, this represents an important argument in favor of achieving better levels of sound insulation in new constructions, as it is common knowledge that the subsequent removal of shortcomings caused by insufficient standards of sound insulation is only possible at enormous cost, if at all. With regard to a small sample of lightweight wooden constructions in Styria, some with sound insulation levels in accordance with the requirements of ÖNORM and others with better but unspecified sound insulation in comparison with ÖNORM, no generally valid trend regarding the impact of achieved sound insulation on total construction costs could be deduced. However, it may be assumed that in particular as far as lightweight wooden buildings are concerned, the effect of improved sound insulation on total building costs is far greater than with massive constructions. However, the effects of annoyance from neighbourhood noise appear thus far to have been underestimated in comparison with other sources. A more recent study argues that annoyance from neighbourhood noise can manifest itself in the form of increased risk of illness, and goes on to show that the negative impacts of neighbourhood noise on health cannot be differentiated from those of traffic noise.. ACKNOWLEDGEMENTS The author acknowledge the support of the study of Hon.-Prof. Dipl.-Ing. Dr. Judith Lang and her team of the technical university of Wien. The complete report could be downloaded at REFERENCES The list of references should be Times Roman type, and should be ordered numerically. Examples of reference styles are given below. Use the pre-defined style [1] Bibliography, shown below. [1] Hon.-Prof. Dipl.-Ing. Dr. Judith Lang, Sound insulation in housing construction Results of an investigation commissioned by Saint-Gobain Isover, (2006) [2] Rasmussen, B., Rindel,J.H., Sound insulation of dwellings Legal requirements in Europe and subjective evaluation of acoustical comfort Proceedings DAGA 2003, (2003). [3] Lang, J., Luft- und Trittschallschutz von Holzdecken und die Verbesserung des Trittschallschutzes durch Fußböden auf Holzdecken, wksb Heft 52, (2004) [4] Scholl, W., Bietz, H, Integration des Holz- und Skelettbaus in die neue DIN 4109 Bericht Physikalisch-Technische Bundesanstalt Braunschweig (2004) [5] Gerretsen, E. Classification of acoustic quality of dwellings - backgrounds of a re-newed Dutch standard, Proceedings inter-noise The Hague, The Netherlands (2001) 6