Giovanni Semprini

Possible correlation between acoustic and thermal performances of building structures

Most European standards required high performance values for sound and thermal insulation in building structures, according to Directive EEC 89/106. Sound transmission and heat transfer in structures have different physical and analytical approach and specific parameters of performance (i.e. sound transmission loss or thermal transmittance) are not directly correlated each others; many kind of structures have also different behaviour depending on mechanical properties of materials, numbers of layers of materials, etc. The aim of this work is to analyse possible correlation between sound transmission performances and thermal properties values in order to evaluated common trends related to physical properties of the various building components, like for example density or surface mass.

Acoustical proprieties of light brick walls and its effects on flanking transmission

Light brick walls 8‐10 cm thick are typical structures frequently used in Italian building constructions as a internal partitions between dwellings and as internal layer of double facade walls. Due to low surface mass and rigid connection to other horizontal and vertical structures, light brick walls are often responsible of high flanking transmission. The simplest acoustic modeling of this structure for the evaluation of sound transmission in buildings, is the approach proposed by the EN 12354 standards, where the brick wall can be considered as a homogeneous structure and main acoustic parameters required are the sound reduction index and the vibration reduction index Kij. The aim of this paper is to analyse results of physical and acoustical properties (sound reduction index, structural reverberation time, radiation efficiency) of a typical 8 cm thick brick wall measured in laboratory testing facility, used as a partition in different test configuration: single layer wall, double brick layer wall with ...

Investigation on the flanking transmission of impact sound insulation of floor

Impact sound pressure level of floors depends, as general rule, on direct sound radiated by the floor excited by a standard tapping machine and on flanking transmission of lateral walls. Depending on the kind of junction between the floor and walls of the receiving room, flanking paths can be more or less important. Requirements of laboratory test specimens are not well specified in EN ISO 140 standards, particularly for junctions of the test floor and lateral walls. In this paper measurements performed at DIENCA laboratory are presented in order to evaluate the influence of flanking transmission on impact sound pressure levels of a standard floor and on impact sound reduction level of standard floor with a resilient layer. Measurements are performed on a 14‐cm‐thick concrete floor in two different conditions: first connected on two sides of the receiving room and then on all four sides. Impact sound pressure levels and vibration levels are analyzed in order to evaluate the contribution of different transmission paths. As the measurements were carried on in the new facility for measurement of the contribution of the flanking transmission, this facility will be exhaustively presented in the paper.

La strategia del progetto ABRACADABRA per azzerare il consumo energetico e bilanciare i costi nella riqualificazione degli edifici esistenti

La sfida energetica dell’Europa 2020 riguarda principalmente la riqualificazione energetica il patrimonio costruito. Contrariamente alle previsioni e agli indirizzi dettati dal BPIE che indicano al 4% il livello target di riqualificazioni annuali, ad oggi, ogni anno, solo il 1,2% degli edifici esistenti in Europa viene rinnovato. Il rinnovamento del parco edilizio esistente, con l’obiettivo NZEB, e difatti frenato dalle risorse economiche necessarie per procedere a tali adeguamenti, che presentano un alto livello di rischio finanziario e di investimento iniziale e lunghi tempi di rientro della spesa. Sviluppare azioni concertate e innovative, colmare il divario degli investimenti richiesti per l’efficienza energetica e contribuire al rilancio del mercato delle costruzioni e alla creazione di nuovi posti di lavoro, sono le sfide da affrontare per la riqualificazione del patrimonio esistente. Il progetto ABRACADABRA (Assistant Buildings’ addition to Retrofit, Adopt, Cure And Develop the Actual Buildings up to zero energy, Activating a market for deep renovation) mira a identificare le possibili soluzioni tecnico-economiche per ottenere un sostanziale incremento del valore immobiliare attraverso la trasformazione energetica e architettonica degli edifici esistenti. L’articolo illustra i benefici dell’approccio basato sulla strategia delle addizioni volumetriche come soluzione in grado di ridurre consistentemente i tempi di ritorno degli investimenti, e incrementare la qualita abitativa attraverso la sinergia tra nuovo intervento e pre-esistente. In questo contesto, il progetto mira a promuovere un cambiamento paradigmatico che investe anche il settore normativo e procedurale allo scopo di accelerare l’adozione di strategie non convenzionali e non esclusivamente “energy-related” nell’obiettivo di energia quasi zero negli edifici esistenti. Viene presentato lo studio di fattibilita condotto su diversi casi di studio sui quali sono applicate e analizzate diverse soluzioni: dalla ristrutturazione di tipo standard a vari scenari di intervento incrementale. Tutte le soluzioni vengono analizzate e confrontate in termini di risparmio energetico e costo-beneficio.

Improvement of acoustic and thermal performances of façades on retrofit buildings

Deep renovation of existing buildings represents an important strategy to go beyond the standard energy retrofit (as the increasing of thermal insulation of building envelope) and to provide more benefits to residents considering non-energetic aspects, like the improvement of architectural quality of building and of indoor life quality. In this context, facades additional elements (balconies, solar greenhouses, etc.) can be effective solutions in order to increase thermal and acoustic performances as well as providing a more living space to the outside. This paper analyzes and compares different technical construction systems for facade improvement in order to define robust solutions correlated both to outdoor climate context (to increase energy performances towards nearly Zero Energy Buildings) and to outdoor noise for a better acoustic sound insulation. A case study is presented, and dynamic energy simulations, performed on a building made with materials and construction technology widespread in Italy ...

Realization of a measurement system for physical and acoustic measurements on brick walls

Aim of this study is the development of a system for the measurement of frequency values of some physical variables such as the damping factor, the thickness of a structural element, the structural reverberation time and the longitudinal wave speed propagation in light brick walls. Such variables are required by the UNI EN 12354-1 normative for the analytical estimation of the sound reduction index R of monolithic elements in the laboratory. The results of the calculation, as a function of frequency, will be shown and compared with the measured values of the sound reduction index R.

Evaluation of the flanking transmission in a scale model of two adjoining rooms

Flanking transmission is the sound propagation through the lateral structures of two adjoining rooms. Evaluation of this transmission is possible with a statistical model of two rooms that considers mainly the reduction in vibration transmission between the partition and the lateral structures. With this model, which is the object of a project of international standard (Pr EN 12354), it is possible to evaluate the transmission through each path, considered independent of each other. The research carried out at the Acoustics Laboratory of the University of Bologna has validated the CEN model by measuring the vibration reduction index and the sound transmission in a scale model. The vibration transmission index has been measured both with transient and steady excitation of the structures, the first by means of a hammer and the second of an electromagnetic shaker. The sound reduction index of each path of transmission has been calculated measuring the mean pressure level in the source room and the mean vibra...

Entertainment park noise control devices

A big entertainment park is operating with noisy attractions near the Garda lake, a pleasant land where people go not only for amusement but also to relax, especially during holiday time. Noise measurements have been made during different periods of daytime and a noise map has been developed taking into account the difference of level between the top of the noisiest attraction and the windows of the most exposed house. Starting from this computerized model, and knowing the emission spectrum of the most relevant sources, it has been possible to design some noise control device useful for reducing the noise exposure level restricted to the exposed houses alone: This was possible combining earth barriers and a hot windstream.