Acoustic Classification of Buildings: Impact of Acoustic Performances of a High Energy-Efficient Building on Quality and Sustainability Indicators
According to similar experiences of other countries, also Italian standards are defining procedures about acoustic classification of buildings, aiming at the determination of indoor acoustic comfort. Acoustic parameters influence building quality in different ways and amounts: the aim of the paper is to attest acoustic performances of buildings, taking into account different noise sources and people expectations. A voluntary certification model was proposed to assess indoor overall quality, which includes a specific Acoustic Performance index (AP) concerning human protection against noise into buildings. According to existing standards, noise measurements were carried out in order to assess acoustic performances of walls, facades, floors and systems in a high energy-efficient multifamily building as a case study. The paper shows a feasible approach to perform indoor acoustic comfort and to support sustainable buildings: a comparison was carried out between impact of acoustic performances on proposed assessment of building quality and on certification of building environmental sustainability introduced by law at regional level.
SOUND INSULATION OF IDENTICAL BUILDING ELEMENTS IN DIFFERENT BUILDINGS
Based on practical experience and experimental investigations, the acoustic performance of building materials and components may vary considerably in different buildings and even compared to the estimation obtained by simulation. The paper focuses on typical questions of building acoustics, such as: the accuracy of the calculation model implemented in order to estimate the sound insulation of building elements; the difference between the predicted value and the actual result of “in situ” sound insulation measurements; the different acoustic performance of identical partitions, although built using the same materials and installation methods; the reproducibility of measurements and the influence of instruments on measurement results, for the same test conditions; any difficulties due to size and irregular shape of the rooms subjected to acoustic measurements. Sound insulation of partitions was assessed by field measurements in residential buildings, according to international standards. Measurements were also performed by different systems to consider reproducibility, measurement uncertainty and instrumental error. Results were analysed and compared, taking into account also predictions based on technical standards. The aim of the paper is to provide a useful contribution to the addressed topics.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.