Approved by the Cabinet Regulation No. 468 of 29 April Latvian Construction Standard LBN Building Acoustics. 1.

Transcription

1 Approved by the Cabinet Regulation No. 468 of 29 April 2004 Latvian Construction Standard LBN Building Acoustics 1. General Issue 1. The following terms shall be used in the Construction Standard: 1.1. Early Decay Time EDT (s) reverberation time determined by the interval of sound extinction from 0 to 10 db Noise barrier a continuous barrier (structure, building or terrain element) placed on the direct sound route from its source to the protected location, which causes diffraction of the sound waves Normalized impact noise level index Ln,w (db) a value which characterizes the impact noise isolation of enclosing structures in laboratory conditions without flanking sound path Normalized impact noise level index L'n,w (db) a value used for evaluation of distribution of the impact noise in a building, which characterizes the impact noise isolation in real conditions with flanking sound path Reverberation time T (s) a time required for the level of sound pressure to decrease by 60 db in a receiver after switching off the sound source. This value is determined by the interval of sound extinction from 5 db to 35 db and is marked with T Speech transmission index (RASTI) (%) indicator of sound comprehensibility with the following evaluation scale: less than 30% bad; from 30% to 45% poor; from 45% to 60% fair; from 60% to 75% good; % and more excellent Sound clarity parameter C 80 (db) correlation of the sound energy of the early (up to 80 ms) and late (after 80 ms) time period perceived by a listener, which characterizes the clearness of the sound from certain points of a room Airborne sound sound (noise) transmission from the sound source in the environment by air Airborne sound reduction index R',w (db) a value used for evaluation of the sound isolation of the internal enclosing structures of a building, which characterizes the sound transmission through the respective enclosing structures, as well as through adjacent structures (via flanking sound path) Airborne sound reduction index R,w a value used for evaluation of the sound isolation of the internal enclosing structures of a building, which is determined by means of laboratory measurements or calculations (does not include transmission via flanking sound path) Airborne sound reduction index R'tr,s,w (db) a value used for evaluation of the sound isolation (with flanking sound path) between a room and

2 2 external territory (source transport noise), i.e. the sound isolation of external enclosing structures of a building and its elements Structural noise mechanical vibrations transmitted in building structures and creating airborne sound Impact noise structural noise transmitted in premises, caused by direct mechanical impact on the structure (e.g., walking on coverings and stairs) Lateral coefficient LF correlation of non-oriented sound energy and direct sound energy perceived by a listener within the period of 80 ms, which characterizes the spatial property of the sound Scope of the Construction Standard 2. The requirements of the Construction standard shall apply to buildings and construction units of any purpose during the whole cycle of their operation: during investigation, designing, construction, capital repairs, reconstruction, restoration, extension and changing their purpose. The requirements of the present Construction standard shall be obligatory to all legal and physical persons. 3. The terms used in the Construction standard shall comply with those prescribed by the Cabinet Regulation No. 337 Regulations on Units of Measurement of Physical Values, their Latvian Names and Spelling as of August 31, When implementing the Construction standard, the requirements of the Latvian national standards may be applied, the list of which has been published in the newspaper Latvijas Vēstnesis (hereinafter referred to as the applicable standards) by the nonprofit limited liability company Latvijas standarts upon request of the Ministry of Economy Goals of Building Acoustics Measures and their Implementation 5. The main goal of building acoustics measures shall be creation of humanfriendly acoustic (sound) environment in buildings and structures in general. Architectonic and construction methods shall be used for attaining the goal hereof. 6. Building acoustics measures include noise control measures and measures for increasing acoustic quality. The noise control measures include construction acoustics, reducing the noises created by technical equipment (engineering equipment), and sound insulation. Their goal is to provide the permissible noise level in premises and territories. Measures for increasing acoustic quality include provision of optimum audibility and euphony in premises and open-air recreation constructions. 7. The parameters of sound sources, anti-noise elements and acoustic environment required for implementation of building acoustics measures are determined by the use of measurements or calculations to be carried out in

3 3 compliance with the requirements of this Construction standard and applicable standards. 8. The acoustic (also those of electro-acoustically equipped premises) calculations, measurements and surveys should be carried out by qualified experts of building acoustics. An expert of building acoustics is a certified specialist with the higher education, at least five years of experience in acoustics, specialization in building acoustics and qualification confirmed by the certificate issued by the Latvian Acoustics association or other acoustics organizations of the European Union. 9. In order to evaluate the acoustic quality of a building or a design or in case of disputes, the client, issuer of the construction permit or another competent authority may request or organize expert-examination of the construction design, carried out by an expert of building acoustics. The expert-examination shall be carried out at a completed or incomplete object for design documentation or the building s premises and structures respectively. If necessary, both methods shall be used at the same time. 2. Acoustics of Premises 2.1. General Requirements 10. The Construction standard shall determine the main requirements for acoustic parameters of building premises and open-air recreation structures. The Construction standard shall specify and supplement the requirements to the acoustics of premises, established by the Latvian Construction standard LBN Public Buildings and Structures and the Latvian Construction standard LBN Multi-storey multi-unit residential buildings. 11. The Construction standard shall not apply to industrial, technical and special-purpose premises (e.g., recording or broadcasting studios, sound editing rooms, audition rooms) to which special acoustic requirements apply. 12. The acoustic parameters of premises and open-air recreation structures should be maintained during the whole period of their operation Requirements for Acoustic Parameters 13. The acoustic parameters of premises, which characterize the acoustic quality of premises shall be determined in accordance with the applicable standards. Acoustic parameters shall be determined and evaluated in octave frequency bands with mean frequencies of 125, 250, 500, 1000, 2000 and 4000 Hz. This subchapter does not specify the limited noise levels in premises, which are regulated in other regulatory enactments.

4 4 14. The general requirements for the acoustic parameters of the auditory zone of premises with different functionality are established in this Construction standard, Annex 1. When planning the purpose of premises, the client shall be entitled to indicate the acoustic parameter values which differ from those provided in Annex 1, as well as to indicate additional parameters. Should no values of parameters are indicated and provided in Annex 1 to this Construction standard, they are determined by a qualified expert of building acoustics upon agreement with the client. 15. The acoustics of premises shall be designed so that the maximum-level values of the effective sound signal do not exceed aural risk values, and exceed the level of side noises at least by 10 db in any place of the auditory zone. The levels of aural risk and side noises shall be determined in compliance with the regulatory enactments which regulate the level of acceptable noise, and the applicable standards. 16. Acoustic parameters in premises of existing buildings and open-air recreation structures shall be determined by the use of acoustic measurements or calculations, and acoustic parameters in premises and structures to be designed or reconstructed shall be determined by the use of calculations or acoustic modeling. In calculation of acoustic parameters of premises by means of 3-D computer modeling, the sound absorbing and sound dispersing properties of the premise surfaces shall be considered. 17. The acoustic parameters necessary for special purpose premises (e.g., sound recording studios, broadcasting studios, sound editing rooms, audition rooms, cinemas with definite sound format) shall be determined by the client (owner of the premises) Requirements to the Room s Shape and Volume 18. The room s shape provides maximally even (diffusive) formation of the sound field by preventing phenomena of sound concentration and standing waves and ensuring optimum values of acoustic parameters. The room proportions may be determined in accordance with the proportion area specified in the Figure 1 of the Annex 2 to this Construction standard. 19. The room s shape shall be chosen so that it facilitates the compensation of direct sound extinction by directed energy of the reflected sound, for example, by the use of special sound reflectors in accordance with the Paragraph 24 of this Construction standard. The reflected part of sound energy should not cause disturbing echo phenomena.

5 5 20. In premises and open-air recreation structures without electroacoustic sound equipment, the most distant stationary seats of auditory shall be arranged not further than: m from the speaker s place in lecture-rooms, conference halls and meeting rooms; m from the plane of stage portal in drama theatres; m from the performers platform in open-air recreation structures, except the open-air stages for choir performances with capacity of more than 50 participants; m from the plane of stage portal in halls of opera-houses; m from the centre of orchestra or chorus zone in halls for symphonic and choral music. 21. In premises with regulated values of acoustic parameters, the correlation of acoustic volume parts (the part of the room construction volume where only direct and reflected sound dominates and which has not been separated by sound isolating elements) to the number of seats (total number of visitors and performers) shall be designed not less than: m 3 per one seat for premises with electro-acoustic sound equipment; m 3 per one seat for lecture-rooms, conference halls and drama theatres; m 3 per one seat for multi-purpose halls, halls for recreation centers and musical comedies; m 3 per one seat for halls of opera-houses and chamber music halls; m 3 per one seat for symphonic music halls; m 3 per one seat for halls of choral and organ music and churches Sound-reflecting and Sound-absorbing Finish of Premises 22. From the aspect of building acoustics, interior elements of premises are divided into absorbing and reflecting elements. The reflecting elements are divided into those with guided reflection and diffusers. Application of these elements directly influences the acoustic parameters of premises. 23. Sound-reflecting elements and constructions should correspond to the following requirements: average sound absorption coefficient is less than 0.1; surface mass is not less than 10 kg/m 2 ; Guided sound-reflecting elements (reflectors) should correspond to the following requirements: their surface area is more than 3 m 2 ; ratio of the shortest and longest edge is not less than 1:3; they are flat or with a curvature radius exceeding 5 m.

6 6 24. The form of the dispersible reflecting elements (diffusers) should be explicitly spatial to provide sound dispersion within the limits specified in Figure 1 of Annex 2 hereof. 25. Dispersible reflecting elements (diffusers) should form at least 20% from surfaces of those premises with regulated acoustic parameters. Location of the respective elements shall be determined by the results of room acoustic measuring or computer modeling. 26. Acoustic absorbers (sound dampeners) are finishing materials and special constructions with a sound absorption coefficient of more than 0.5 at least in one of the frequency bands referred in Paragraph 13 of this Construction standard. The sound absorption coefficient of materials and constructions should be determined and evaluated in accordance with the Law On Conformity Assessment and the applicable standards. 27. Depending on the transformation type of sound energy, absorbers are divided into the following groups: Cotton-type and porous absorbers: sound energy is transformed into heat in these materials because air molecular friction arises in pores thus absorbing the sound in most effective way within the range of medium and high frequencies with a minimum sufficient thickness Membrane-type absorbers: transformation of energy takes place because of the membrane resistance to fast bending and the intermediate-layer resistance to pressure; these absorbers are efficient within a narrow band of low and medium frequencies (1 2 octaves) Volume resonators: various adjacent volumes, alcoves and gaps connected to the room acoustic volume, which operation principle is based on the mechanical spring mass model. The air locked in the volume and the neck form the spring mass system providing absorption in a certain frequency. These absorbers dampen selectively their effective band usually does not exceed one third octave Combined absorbers: several absorbers mentioned in Sub-paragraph 27.1, 27.2 and 27.3 of this Construction standard may be used at the same time (e.g., perforated coating filled with cotton absorber). Higher coefficient values ( ) are characteristic to the referred absorbers within a wide range of frequencies ( Hz). 28. Acoustic absorbents are used in premises with regulated acoustic parameters only on the basis of the results of room acoustic measuring or computer modeling. Premises with the only limitations for the values of maximum reverberation time are mentioned in Annex 1 of this Construction standard. If the parameters are not regulated, the conditions referred in this sub-chapter may be ignored Special Requirements for Different Types of Premises

7 7 29. The clarity and audibility of the sound is maintained in auditoriums, conference halls, dramatic theater halls and similar premises. Their acoustic volume should not exceed 2000 m 3 (3000 m 3 for drama theater halls) if those premises are not equipped with electro-acoustic sound systems. The surfaces in proximity of a performer (speaker) shall be made of sound-reflective materials. If absorbers are necessary on the basis of calculations, they shall be installed in the distal end area or side areas of the room. Electro-acoustic sound systems are used if the maximum distance from the speaker s position (area) to the most distant seats of auditory is more than 20 m. 30. For concert halls, the permitted acoustic parameters in performers areas differ from those in audience area: reverberation time T may be less by 30% but C 80 and RASTI values may exceed the norms determined in Annex 1 of this Construction standard. Dispersed reflectivity shall be provided in the performers' area by placing diffusers close to the performers. Concert halls with the length over 35 m should be equipped with stationary electro-acoustic sound systems. 31. In order to secure the acoustic balance, the depth of the opera-house orchestra pit against the forestage should not exceed 2.5 m, except in the case of transforming floors. The floor and walls of the orchestra pit should be made to provide damping of low-frequency sounds (air interlayer under the floor shall be greater than 0.5 m and behind the paneling shall be greater than 0.1 m). Percussion and brass instrument groups may be partially covered with the forestage floor console. Additional sound diffusers should be installed in orchestra pits, and bass sound super-absorbers (100% absorbers) should be installed in the floors where technically possible. The pit floor area for every musician should not be less than 1.2 m². Halls of opera-houses with length over 30 m shall be equipped with stationary electro-acoustic sound systems. 32. When determining the acoustic parameters for all-purpose halls (also halls for recreation centers and large clubs), the average indices established for different performance types should be used. Transformable rooms should be designed where technically possible by adjusting the acoustic parameters for every function or different functions. The following transformations are possible: shape transformations of the room changes in location or turning angle of respective elements and details, which enable changes in the separation of sound reflection within the hall; room volume transformations changes in acoustic volume and seat volume of audience, which cause changes in reverberation parameters (T, EDT and others); finishing transformations changes in surface finishing during the utilization of the room, which cause changes in the surface absorption coefficient and respectively influence reflection structure and reverberation processes.

8 8 33. All-purpose halls shall be equipped with a stationary electroacoustic sound system. 34. For cinemas and other premises to be equipped with electro-acoustic sound systems (e.g., discotheques, dance floors), short reverberation periods shall be maintained by simultaneously taking into account the requirements of sound field diffusity. Particular requirements depend on the room type. Additional requirements for other room groups should be determined in accordance with the applicable standards. 35. For cult premises, the requirements to the reverberation period should be satisfied with sufficient clearness of the sound. The referred conditions require sufficient acoustic volume with the presence of early sound reflection. 36. For open-air recreation structures (e.g., open-air stages), a sufficient sound level should be provided in the auditory area at least 10 dba above the side noise level, as well as possibility echo effects should be controlled by adjusting the acoustic parameters of open-air recreation structure to those of the room with analogical functions in accordance with Annex 1 of this Construction standard. For especially large sound sources (e.g., united choirs and orchestras), direct sound delays in different audience locations should be controlled, by taking into account the influence of prevailing wind, terrain and greeneries. 3. Sound Insulation 3.1. General Requirements 37. Building structures should be designed and built so that interior and contiguous areas provide the noise levels in compliance with the requirements of the regulatory enactments on the permissible values of acoustic noise. Building constructions and materials with sound insulating properties shall be used which ensure the implementation of the requirements specified in regulatory enactments. This subchapter specifies the following properties of building constructions and materials: insulation of airborne sound, impact noise and structure noise. 38. Evaluating the acoustic qualities of building constructions and products shall use the results of laboratory analysis, and calculations and measurements on completed or incomplete objects, as well as product technical specifications shall be used if the results of laboratory analysis are not available. In order to evaluate the insulation qualities of a building and its separate elements, the following digit parameters should be applied: airborne sound reduction index R'w and R'tr,s,w (db); normalized impact noise level index L'n,w (db). 39. Sound insulation properties of structures should be evaluated and acoustic measurements should be performed in accordance with the applicable standards.

9 9 40. The minimum sound insulation requirements for internal enclosing structures have been specified in Annex 3 of this Construction standard. Municipalities may advance higher sound insulation requirements in their local construction regulations. 41. A structure shall be designed and built so that to maintain the acoustic properties of building constructions and building wares within the whole period of their operation Sound Insulation Requirements for Internal Enclosing Structures of Buildings 42. The standardized sound isolation quantities are sound reduction index R'w and normalized impact noise level index L'n,w which are specified in Annex 3 and 4 of this Construction standard. The surfaces of the building s internal enclosing structures shall be formed in accordance with sound insulation requirements as stated in Annex 3 and 4 of this Construction standard: airborne sound reduction index R w should not be lower than the values specified in Annex 3 and 4 of this Construction standard but normalized impact noise level indexes L n, w should not exceed those specified in Annex 3 and 4 of this Construction standard. Index R w values correspond to the necessary sound insulation between rooms in a vertical and horizontal direction. The index L'n,w shows the required impact noise isolation in all directions (vertically, horizontally and diagonally). The conformity to the requirements for the insulation of impact noise shall be determined for premises with floor surface area of at less 2.5 m The sound insulation of the internal enclosing structures of a building shall be formed so that to ensure an indirect noise transmission within the adjacent building constructions. The technical performance of pits and communications (e.g., ventilation shafts and pipes going through the building constructions) should maintain the level of sound insulation in walls and ceilings within the limits determined in this Construction standard. 44. Sound insulation values for the premises not mentioned in Annex 3 of this Construction standard (e.g., industrial premises) shall be adopted in compliance with the acoustic conditions pursuant to Annex 4 of this Construction standard, by choosing the value which is most suitable for the premise functionality. If a designer applies data mentioned in Annex 4 of this Construction standard, his/her particular choice shall be substantiated in a construction design. 45. The necessary sound insulation between premises with maximum sound levels exceeding 100 dba (e.g., discotheques, dance floors, industrial premises) or with the permissible sound levels being less than 30 dba (e.g., studios, sound editing rooms) shall be determined only by the use of calculations.

10 Sound Insulation Requirements for External Enclosing Structures (Facades) of Buildings 46. Sound insulation requirements for external enclosing structures and their elements should be advanced depending on the noise level in the surrounding territories and premises of a building. The external noise level should be determined by using measurements or calculations. The permissible noise level in building territories and premises should be determined in compliance with the regulatory enactments on the permissible values of acoustic noise. The sound insulation of external enclosing structures and their elements should be evaluated in compliance with the applicable standards. The sound insulation of external enclosing structures may be considered as sufficient if it ensures protection of inside buildings against the outside noise and the surrounding territory against the noise originating from the internal premises. 47. The sound insulation of external enclosing structures in the presence of outside noise sources may be approximately determined by applying Annex 5 and 6 of this Construction standard. The standardized sound insulation quantity for external enclosing structures is the sound insulation index R tr,s,w specified in Annex 5 of this Construction standard. The external noise level LpA, eq,t should be determined in the distance of 2 m from the external enclosing structure by taking into account the sound reflection therefrom. If the external enclosing structures contain various elements with different sound insulation (e.g., walls with windows or doors), the sound insulation index determined in accordance with Annex 5 of this Construction standard should be applied to the insulation of the whole structure. A corrective coefficient should be applied to the index R tr,s,w in accordance with Annex 4 of this Construction standard and based on the proportion of the enclosing structure area and the room floor area. The sound insulation indexes of external enclosing structures should not be lower than those specified in Annex 5 and 6 of this Construction standard. 48. Sound insulation indexes R w and Rw are taken into account when calculating the sound insulation of external enclosing structures and choosing separate external enclosing elements. Approximately R tr,s,w = R w,res, where R w,res is the total sound insulation of external enclosing structure, determined on the basis of the sound insulation indexes R w and Rw for separate elements of the external enclosing structure. 49. For premises with floor area up to 25 m², the sound insulation of windows should be determined by applying the approximation method: The value 10 lg S/Sa should be subtracted from the index R tr,s,w value determined in accordance with Annex 5 and 6 of this Construction standard, where S stands for the external enclosing structure s area and Sa stands for the area of the room window (door). If the window takes more than 50% from the area of an external wall, the sound insulation value of the window shall be equal to the sound insulation index of the external enclosing structure. The approximation method

11 11 shall be applied to heavy materials of external walls (e.g., concrete or brick walls). The approximation method shall not applied to light, multi-layered materials with mass less than 100 kg/m², as well as in large rooms where floor area exceeds 25 m². 50. When providing the sound insulation necessary for external enclosing structures, the elements designed ventilation (e.g., airways in windows or walls) should not reduce the sound insulation of the structure so that the level of noise passing in the room exceeds the permissible level. To ensure very low noise level in premises situated in noisy surroundings, the premises shall be ventilated by using an air-conditioning equipment or fresh air inlet through air pipes from ventilations systems. 51. If noise sources are located in buildings (interior premises) and the surrounding territories are protected, the sound insulation required for external enclosing structures shall be determined by applying calculations only (Annex 5 and 6 of this Construction standard should not be applied) Insulation of Structural Noise 52. Taking into consideration the noise level of technical equipment and its position in relation to the premises with regulated noise levels, additional measures should be first taken for reducing structural noise transmission. The necessity for additional measures shall be determined individually for each particular case. The characteristics of the noise produced by technical equipment shall be determined by the respective standards and specified in the equipment certificates. 53. Equipment generating structural noise should not be installed close to the premises where silence is required. In order to reduce structural noise, flexible damping covers or pipe pylons shall be fitted on pipes which go through the enclosing structure. Translational and rotational units (e.g., pumps, compressors, ventilators) shall be mounted on dampers. Structural noise should be evaluated in compliance with Paragraph 8 of this Construction standard and the applicable standards. Connections between the pump and ventilation unit and the air conduct (pipeline) shall be flexible. 54. Water supply equipment should not be mounted on walls adjoining the adjacent dwelling premises or other premises of comparable use in public buildings where silence is required. If water supply equipment is necessary, only the 1-st group equipment shall be used and the mass of homogeneous wall structure shall be at least 200 kg/m². Classification groups of water supply equipment according to its sound pressure level Lap shall be determined pursuant to the applicable standards. For light, multi-layered wall structures, the adequacy of solution shall be proved by tests. Additional measures should be taken for reducing structural noise if the water supply equipment is mounted in building constructions and fundamentals by the use of the 2-nd group equipment and walls are adjoined to the

12 12 premises requiring silence. The flow pressure within the system shall not exceed 0.3 MPa. 4. Noise of Technical Equipment 55. Technical equipment includes the technical communications of a building (e.g., water supply and drainage devices), heating systems, ventilation and cooling devices, elevators and similar devices, as well as devices which produce noise in industrial, service premises and premises of comparable use. 56. The value of noise pressure produced by technical equipment in premises with regulated noise pressure and in surrounding territories shall not exceed the values specified in regulatory enactments on hygiene requirements. 57. Transmission of the noise produced by technical equipment should be reduced by taking building acoustics and noise control measures during the installation process of equipment and communications, by ensuring the required sound insulation of enclosing structures and using the following specific equipment for the reduction of noise and vibration transmission: noise insulation cases or covers installed on the equipment; installation of a noise barrier; formation of flexible connection parts; noise silencers, dampers and damping supports. 58. Acoustic qualities necessary for the specific equipment shall be determined by calculations and considering the acoustic parameters of noise sources and the permissible sound levels in premises and territories. 5. Construction Acoustics 5.1. General Requirements 59. The requirements defined in this Construction standard supplement the anti-noise requirements of the Construction standards for territory planning, as well as specify the aims of the design planning and tasks in protecting constructions from noise Forecast of Acoustic Discomfort Areas 60. Acoustic discomfort areas (noise protection areas) are environmental areas exceeding the permissible noise levels specified in regulatory enactments. The environmental noise level shall be determined by applying the methods stated in the applicable standards.

13 The boundaries of acoustic discomfort areas shall be determined individually for each period of the day by the use of acoustic measurements or calculations in compliance with the respective regulatory enactments. Calculations shall be performed in accordance with the applicable standards. If several noise sources are active or several buildings are influenced, network acoustic measurements or 3-D computer modeling shall be carried out. Acoustic measurements may be performed regularly or by using continuous acoustic monitoring. 62. In calculating acoustic discomfort areas, environment and atmosphere conditions and parameters shall be considered pursuant to the applicable standards. 63. Acoustic discomfort areas may include only building territories which allow higher noise levels than those detected or forecasted in the respective area. 64. Only those buildings may be located in acoustic discomfort areas, the sound insulation of external enclosing structures of which ensures adequate sound levels in the inner premises pursuant to this Construction standard and other regulatory enactments on the permissible noise levels. 65. The boundaries of acoustic discomfort areas may be reduced by designing and implementing noise control measures at the noise source, noise distribution routes or protected object. 66. Acoustic discomfort areas shall be determined and documented for all permanent external noise sources (e.g., transport lines, airports, airdromes, factories, service companies, transformer substations) if their noise capacity levels exceed 70 dba, as well as for internal noise sources of buildings if their external (2 m from facade) equivalent noise levels exceed 45 dba. 67. The areas of aircraft generated noise shall be determined in accordance with the applicable standards. 68. The noise capacity level (for evaluation of sound pressure levels in the environment) for manufacturing enterprise shall be determined in accordance with the applicable standards Noise Control Measures 69. The following noise control measures should be primarily carried out at the source of noise: adjusting condition of the noise source and precise observance of exploitation norms; replacing the noise source with acoustically less active equivalent; damping of the noise source thus reducing its acoustic reflection; limiting the time of noise source operation.

14 The following noise control measures shall be carried out at noise transmission routes: extension of a sound transmission route by moving the protected object from noise source or by moving the respective noise source from the protected object; sound insulation complete isolation of a noise source from the environment by using, e.g., enclosing structures or covers, pursuant to the requirements of Chapter 2 of this Construction standard; sound screening creation or exploitation of barriers (e.g., screens, buildings, terrain elements) eliminating a direct sound transmission; sound absorption and absorption screening measures (e.g., replacement of the territory covering, utilization of greenery and forest tracts). 71. The following noise control measures should be carried out at the protected object: sound insulation complete isolation of the protected object or premise from the noisy environment by the use of enclosing structures in accordance with requirements stated in Chapter 2 of this Construction standard; architectural design orientation of the protected premise or area towards noiseless directions. 72. Sound screening measures include the use of noise barriers: constructions, buildings and terrain elements (e.g., embankments, entrenchments). Acoustic effectiveness of the screen shall be determined by the use of measurements or calculations in accordance with the applicable standards. The acoustic effectiveness of the screen depends on its outer dimensions, materials and position, and it varies in different environment locations behind the screen. If a protected building located on the opposite side of the noise source, the screen surface directed towards the noise source shall be covered with sound absorbing material. Mass of the screen surface should not be less than 30 kg/m². Doors, gateways and passages of the screen ensure an appropriate sound insulation. 73. Sound absorption and absorption screening measures result in modeling such territory surfaces which absorb noise (e.g., lawns, farmland, bushes, continuous greenery zones and tracts). The acoustic effectiveness of the referred measures should be taken into consideration if they are active all year round, not only during the vegetation season. The acoustic effectiveness shall be determined by the use of measurements or calculations in accordance with the applicable standards. Minister of Economy J. Lujāns

15 15 CABINET OF MINISTERS OF THE REPUBLIC OF LATVIA April 29, 2004 Regulations No. 468 Rīgā (minutes Nr. 26, 14. ) Regulations on the Latvian Construction Standard LBN Building Acoustics Issued pursuant to Section 4, Paragraph 2 of the Construction Law 1. These Regulations confirm the Latvian Construction Standard LBN Building Acoustics (hereinafter referred to as the Construction Standard LBN ). 2. Construction standards and regulations SNiP II Protection Against Noise of the former USSR are not applied in Latvia from July 1, The revision of construction design documentation in conformity with the requirements of the construction standard LBN shall not be required for construction designs which have been submitted for approval by June 30, 2004 and the technical solutions of which conform to the requirements of the regulatory enactments applied in the relevant period of time. 4. Ministry of Economics: 4.1. in cooperation with the technical committees for the standardization of the sector promotes the development of Latvian national standards and the adaptation of international organization standards required for compliance with these regulations; 4.2. issues systematic provisions for the execution of the construction standard LBN These Regulations shall come into force on July 1, Informative reference to the European Union Directive These regulations include legal norms resulting from the Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products. Prime Minister Minister of Economy I. Emsis J. Lujāns

16 16 Annex 1 Latvian Construction Standard LBN Building Acoustics (approved by the Cabinet Regulation No. 468 of 29 April 2004) Requirements for Room Acoustics Parameters within Hz No. of premises T (T 30 ) (sec.) C 80 (db) LF RASTI (%) 1 Halls for organ and choral music, churches* 0.57 V 0.15 > 4 > 0.22 > 40 2 Halls for symphonic music* 0.48 V > 0.20 > 45 3 Halls for chamber music and opera-house 0.46 V > 0.15 > 50 4 All-purpose halls, halls for recreation centers, clubs, musical comedies* 0.42 V 0.13 > 0 > 0.12 > 53 5 Rooms for speech performances (e.g., auditoriums, conference halls, drama0.37 V 0.13 > 1 > 0.10 > 60 theatres)** 6 Halls of cult buildings, parish houses, (except churches)* 0.3 lgv > 1 > 0.10 > 50 7 Rooms with electro-acoustic sound system0.2 (V/100) 0.33 > 0 > 60 8 Staircases and hallways in dwelling houses and public buildings < Rooms for educational institutions (except music classrooms) > 2 > Music classrooms and rehearsal rooms > 0 > 0.15 > Sports halls < 1.5 > 3 > Swimming pools < 2.0 > 40 Notes: 1. RASTI values should be provided when the sound source is in speech or electroacoustic condition. 2. Spatial coefficient LF values in music source condition in the room. 3. Acceptable deviations from the values in the table are +/ 5 %. 4. Values apply to rooms containing 70% of expected visitors. * T values in the range of Hz are recommended to increase by 10 20%, and those within the frequency of 4000 Hz are recommended to decrease by 5 10%. ** T values in the range of Hz are suitable for Hz band, and it is acceptable to decrease them within the frequency of 4000 Hz by 5 10%. Minister of Economy J. Lujāns

17 17 Annex 2 Latvian Construction Standard LBN Building Acoustics (approved by the Cabinet Regulation No. 468 of 29 April 2004) Geometrical Parameters of Rooms and Internal Surfaces Figure 1 Optimum proportion area of a room Figure 2 Dimensions of sound diffusion elements Minister of Economy J. Lujāns

18 18 Annex 3 Latvian Construction Standard LBN Building Acoustics (approved by the Cabinet Regulation No. 468 of 29 April 2004) Requirements for Sound Isolation in Internal Enclosing Structures Building and roo Requiremen sound isolation Notes I. Residental buildings Airborne sound reduction index R'w (db) 1 Between dwelling premises 54 applies to all types of residential buildings 2 Between dwelling premises and public, office premises Between apartments and rooms with noise sources with maximum noise levels up to 80 dba dba dba 54 public premises include staircases, entrance-halls and hallways, as well as attic and cellar usable facilities ventilation chambers, engine rooms, garages, coffee-houses, bars, shops restaurants, sports halls 4 Between the rooms within one d 45 ceilings between the rooms in two-storey dwelling, partition walls without doors between rooms and between the kitchen and the room Entrance door to the dwelling opens directly to the staircase opens to the hallway separated the staircase with a wall 35 27

19 19 Normalized impact noise level index L'n,w (db) 6 Between dwellings 54 requirements do not apply to bath toilet, sauna and similar rooms w the dwelling 7 Between balcony, staircase, 58 hallway, toilet and dwelling 8 Between dwelling and the room with a noise source 9 Between dwelling premises with two-storey apartment 48 if necessary, additional measures should be taken for reducing structural noise 63 II. Temporary residences 10 Between bedrooms (hotel rooms) 11 Between bedrooms (hotel rooms and public premises (staircases, hallways, entrance-halls, refreshment rooms) 12 Between bedrooms (hotel rooms) and rooms with a noise source with maximum noise levels 12.1 up to 80 dba dba dba Between isolated hotel rooms Doors or integrated doors 32 between bedroom (hotel room) and staircase or public hallway Airborne sound reduction index R'w (db) 52 temporary residences include hotels, campsites, guest houses, tourists and leisure facilities kitchens, technical and staff rooms coffee-houses, bars, shops restaurants, sports halls

20 20 15 From on bedroom (hotel room) to another 16 Between public premises (balcony, stairs, entrancehall, hallway, refreshment room) and bedroom (hotel room) 17 Between premises with a noise source (technical service and maintenance rooms, restaurant and kitchen facilities) and bedroom (hotel room) Normalized impact noise level index L'n,w (db) 57 does not apply to the bedroom balcony, bathroom and toilet if necessary, additional measures should be taken for reducing structural noise III. Social care and rehabilitation institutions 18 Dwelling premises in resthomes and rehabilitation institutions sound isolation requirements for dwellings are preferred Minimum requirements for sound isolation shell be applied in conformity with Paragraphs 10, 11, 12, 13, 14, 15, 16 and 17 of this Annex (Temporary residences) IV. Medical treatment and health care institutions 19 Between wards, between wards and premises of comparable use 20 Between wards, premises of comparable use and public premises (staircases, hallways, entrance-halls, recreation rooms, diningrooms) Airborne sound reduction index R'w (db) premises of comparable use include examination and treatment rooms, consulting rooms

21 21 21 Between operating rooms, between operating rooms and other roo (except rooms with noise-prod equipment) 22 Between intensive care wards, between intensive care wards a hallway 23 Between wards and premises o comparable use, and kitchen, technical service and maintena rooms 24 Between special purpose room hearing examination room) an rooms Doors, windows or integrated door and window units between wards and hallway between intensive care room a hallway between the hearing examinat room and other rooms 26 From wards and premises of comparable use to other room 27 From public premises (stairca hallways, entrance halls, recre rooms) to wards and premises of comparable use 28 From rooms with a noise sour (kitchen, technical service and maintenance rooms) to wards premises of comparable use if walls include windows Normalized impact noise level index L'n,w (db) 57 the wards and premises of compa use mentioned in Paragraphs 10, and 28 of this Annex also includ operating rooms 57 if necessary, additional measures be taken for reducing structural n

22 22 V. Educational and science buildings 29 Between school classrooms and premises of comparable use, betw the aforementioned rooms and p premises (staircases, hallways, h entrance halls) 30 Between large auditoriums (mor 100 seats), between study rooms large auditoriums. Airborne sound reduction index R'w (db) 54 Requirements specified in Paragraphs 29, 30, 31, 32, 33, 34, 35, 36, 37 and 38 of this Annex shall not apply to educational institutions for children with hearing disorders. Premises of comparable use include study rooms and other similar lecture rooms Between large auditoriums and public premises (staircases, hallw halls, entrance halls) 32 Between classrooms, study rooms, auditoriums and special classrooms 33 Between specific study rooms and shared facilities (staircases, hallways, halls, entrance halls) 34 Between classrooms, study rooms, auditoriums and kitchen, dining hall Doors, windows or integrated door window units between classrooms, premises of comparable use and hallways between classrooms and premises regarded as classrooms (except music classrooms) special classrooms include music classrooms, handcraft rooms and sports halls Between group rooms and 50 bedrooms in pre-school institution 37 Between pre-school institution 52 group rooms, bedrooms and kitchen 38 Between pre-school institution 55 group rooms, bedrooms and music room or sports hall 39 Doors from pre-school institution 30

23 group rooms or bedrooms to hallway 40 From classroom (study room) to another classroom (study room) 41 From public premises (staircases, hallways, halls, entrance halls) to classrooms (study rooms) 42 From special classrooms to usual classroom (study room, auditorium) or another special classroom 43 From a large auditorium to study room or another auditorium 44 From pre-school institution group room, bedroom to other group rooms and bedrooms 45 From public premises (hallway, staircase, hall) of a pre-school institution to group rooms and bedrooms, from kitchen to group rooms and bedrooms 46 From the music room, sports hall of a pre-school institution to its group rooms and bedrooms 23 Normalized impact noise level index L'n,w (db) 60 if necessary, additional measures be taken for reducing structural n VI. Administrative buildings Airborne sound reduction index R'w (db) 47 Between work rooms, between wo rooms and staircases, hallways, ha entrance-halls 50

24 Doors, windows or integrated door and window units from work rooms to hallways, staircases, halls, entrance halls from halls to hallways, staircases, halls, entrance halls Between work rooms and rooms containing noise sources with maximum noise levels: up to 80 dba dba dba 50 Between courtrooms, meeting rooms and hallways, staircases, halls, entrance halls, work rooms and technical rooms 51 From work room to work room, from public premise to work room 52 From premises containing a noise source (kitchen, technica service and maintenance room). to halls Normalized impact noise level index L'n,w (db) kitchen, technical and staff rooms coffee-houses, bars, shops, restaurants, sports halls VII. Culture and entertainment institutions 53 Between halls, library reading rooms and lobby, halls or hallways 54 Between halls, library reading rooms and unused attic, cellar and storage facilities Airborne sound reduction index R'w (db) Between halls and library reading rooms and rooms containing noise sources with maximum noise levels: up to 80 dba dba dba additional measures are taken for reducing structural noise

25 25 56 Between halls, library reading 55 rooms and work rooms 57 Between auditoriums and 62 conference halls 58 Between theatre halls and 69 concert halls 59 Between projection rooms 75 Normalized impact noise level index L'n,w (db) 60 From premises containing a 48 noise source (technical rooms, equipment rooms) to the hall 61 From the lobby, halls, 53 hallways and work rooms to halls 62 From hall to hall From halls to office rooms 63 VIII. Sports buildings 64 Between sports halls, swimming pools and lobby, halls or hallways 65 Between sports hall, swimming pools and bars, coffee-houses 66 Between sports halls, swimming pool and work rooms 67 From sports halls, swimming pools to coffee-houses, bars and work rooms Normalized impact noise level index L'n,w (db) 63 Minister of Economy J. Lujāns

26 26 Annex 4 Latvian Construction Standard LBN Building Acoustics (approved by the Cabinet Regulation No. 468 of 29 April 2004) Optional Values of Sound Insulation Indexes R w/l n,w (db) for Internal Enclosing Structures No. Acoustic condition in the Protection level of the room to be isolated room with a noise source low medium high 1 Quiet 42/65 47/60 52/55 2 Noiseless 47/60 52/55 57/50 3 Noisy 52/55 57/50 62/45 4 Very noisy 57/50 62/45 67/45 Minister of Economy J. Lujāns

27 27 Annex 5 Latvian Construction Standard LBN Building Acoustics (approved by the Cabinet Regulation No. 468 of 29 April 2004) Requirements for Airborne Sound Isolation in External Enclosing Structures (Facades) in relation to Outdoor Noises No. Type of premises 1. Sleeping accommodations in health care institutions, operating rooms, auditoriums 2. Living rooms in apartments and high ranked hotels, sleeping accommodations in preschool and social care institutions 3. Office rooms, temporary residence rooms, classrooms, study rooms 4. Work rooms, waiting rooms, apartment auxiliary rooms, restaurant and café facilities Minimum airborne sound reduction index R tr,s,w (db) provided that T limit of the outdoor noise level LpA,eq is (db): up to * * * Note. * Outdoor noise level is too high for these premises, and special measures should be taken to reduce the noise level. Minister of Economy J. Lujāns