Gianfranco Cellai

Correlation between facade sound insulation and urban noise: A contribution to the acoustic classification of existing buildings:

The aim of this work is the definition of a methodology to analyze the number of buildings exposed to every noise level band, to estimate the required facade sound insulation for indoor comfort, and to evaluate the acoustic classes that would characterize existing building facades adopting the proposal for a new International Organization for Standardization standard. In particular, a relationship based on a statistical approach is analyzed between outdoor noise, determined according to the European Noise Directive, and the limit values for the acoustic classification of buildings that are going to be implemented in the proposed International Organization for Standardization standard. Building exposure to noise is described through the indicator Lden as reported in the noise maps elaborated, according to the European Noise Directive, with reference to some major Italian towns. As a result of the application of the proposed methodology, the facade insulation required to obtain an adequate indoor comfort is determined.

Transparent Building Envelope: Windows and Shading Devices Typologies for Energy Efficiency Refurbishments

Main typologies of windows, typical of the existing buildings, and innovative solutions, special glasses, and shading devices (fixed shading, mobile shading, roller blinds, and curtains) are described and assessed. The windows and solar shadings’ appropriate choices are evaluated on the basis of a case study. For each of these solutions, thermal efficiency, natural lighting, and acoustic performances have been assessed with appropriate calculation codes. Dynamic computational methods with a graphical interface are used (EnergyPlus, through the Design Builder interface, for energy simulations, RELUX to simulate natural lighting, and DISIA for the acoustic simulations). Four representative climatic datasets corresponding to various locations (Berlin, Milan, Florence, and Athens) were considered. Appropriate performance indicators (defined by regulations or conventionally applied in science) have been identified in order to analyze performances and to evaluate different strategies for the achievements of energy efficiency and of comfortable environments: Q sw (winter solar gains), θo (operative temperature), F w (reduction factor of winter solar gains), DF (average daylight factor), UDI (useful daylight illuminance), daylight uniformity, D 2m, nTw (acoustic insulation of facade normalized with respect to the reverberation time), and Δl fs (sound pressure level difference due the facade shape). Starting from the performance evaluation of existing buildings, according to a logic implementation of consequential performance, this study provides for the assessment of different phases: the first interventions (phase A), replacement of existing windows with other high-energy performance ones (phase B), adaptation of the thermal transmittance of opaque envelope to national limits (phase C), and introduction to solar systems and solar control glasses (phase D). Then, the effect of screens and windows on the reduction in the thermal loads in the summer season and on the thermal comfort has been assessed, together with the influence on visual and acoustic comfort of different configurations of windows and shielding. Finally, a comprehensive evaluation on the aspects of energy consumption, natural lighting, acoustic comfort, and technical feasibility (TF) is carried out.

Sound Transmission between Rooms with Curtain Wall Façades: A Case Study

Curtain walls have reached good performances in terms of façade sound and thermal insulation, as well as solar protection. Nevertheless, the sound insulation performance of the partition between adjoining rooms with continuous curtain wall façades is often reduced by the presence of direct and flanking transmission through the junction with the façade itself. In this work, flanking and direct structural transmissions are analysed with reference to the joints of the mullion of the curtain wall with lightweight plasterboard partitions. Airborne sound insulation and vibration measurements were made in two adjacent rooms affected by the acoustic problems determined by the curtain wall joint. Traditional acoustic measurements, carried out according to EN ISO 16283–1, highlighted problems in sound insulation between rooms, but without any indication on different sound transmission paths through the wall. Vibration measurements were made for every part of the system (frame columns and beams, window panes, plasterboard wall, plasterboard false ceiling, etc.) to better understand the sound transmission paths in these kinds of structures. In this paper the results of this analysis are presented. Moreover, taking into account previous works and measurements made in this research field, different solutions for curtain wall structures are analysed and technical suggestions are given to improve airborne sound insulation between rooms separated by partitions mounted up to metal frames.

Sound Insulation Requirements in Hospitals: Comparisons and case studies

Italian and EU regulations for sound insulation of hospitals are very hard to be satisfied. Especially with reference to sound insulation from outside noise, the simultaneous presence of important sound sources (refrigerating units, fans and others) and of sensitive receivers (the patients) imposes high requirements for facade sound insulation. Moreover, the necessity to assure high values of natural lighting in interiors imposes the use of large windows on facades. By using the tabular estimation model defined by annex B of the European Norm 14351 for the calculation of the performance of windows and the model of EN 12354‐3 for the performance of facades, it is easy to show that the limiting values defined by the Italian Law can be achieved only with a perfect realisation of the building construction. In the paper the comparison between EU regulations for hospitals is shown. Moreover, different case studies of hospital buildings are analysed either with a theoretical approach or with measures carried out in site.

Influence of flanking transmission in typical Italian constructions

Actually acoustic performance of building components are analysed with reference to standardised conditions, in laboratories with suppressed flanking transmission. Laboratory results often show values of the performances quite different from those measured in real buildings, as a consequence of flanking transmission and of different conditions of realisation in situ. Moreover, in spite of all efforts aimed to standardise laboratory test conditions, often we find different certified performances of same building components obtained in different laboratory. In some cases, these differences may be very relevant. Besides, the Italian decree on acoustic requirement of buildings prescribes limiting values to be measured in situ. For these reasons, many producers of building materials and components more frequently presents in their depliants both laboratory values and in situ values of acoustic performances of their products. The paper shows the preliminary results of an research aimed to verify acoustic performances of partition walls and floors in a laboratory which respect conditions of ISO 140‐1, but with the presence of relevant flanking transmission, similar to real buildings. The relevance of the flanking transmission has also been modified by means of a lining applied to the ceiling of the receiving room of the laboratory.

Technical Note: Determination of Impact Noise of Floors Based on Vibration Measurements

Field measurement of acoustical performances of buildings is difficult where construction has not been completed. The absence of doors, windows and other finishing details, generates sound transmission paths, which can modify the results of measurements. In these cases, acoustical performances of building, such as sound reduction index and impact noise, can be determined through the temporary close of all openings, or through the measurement of the vibration velocity level of the partitions examined. Both techniques allow the elimination of airborne transmission paths, while the second also permits the evaluation of the contribution of structural flanking transmission. In this paper, a technique is described for the estimation of impact noise of floors from measurements of velocity levels. Results are presented for a concrete floors and a comparison given between the traditional and new type of measurements.

Air Quality And Ductwork Contamination: State Of The Art And Guidelines

If the design, installation and maintenance of HVAC systems does not follow suitable standards, they can give rise to several problems, such as: excessive installation and maintenance costs as well as hygienic problems for dust deposition and accumulation. The paper deals with the state of the art duct contamination. The paper also presents the used methodology and the obtained preliminary results of a study carried out on ten hospital buildings. Finally some considerations about the effectiveness of some cleaning methods are presented.