Papers by Francesco D'Alessandro
The Journal of the Acoustical Society of America, 2013
The present paper reports a socio-acoustic survey carried out in three large urban parks in Rome,... more The present paper reports a socio-acoustic survey carried out in three large urban parks in Rome, selected on the basis of the outcome of a preliminary online survey. According to the experimental protocol applied in a previous study carried out in Milan and Naples, binaural recordings in 85 sites and interviews with 266 users of the three parks were performed only during the day in summertime. On the basis of selected acoustical descriptors, the sonic environment of the three parks was categorized and, thanks to statistical analysis, three clusters were identified. The results confirm that the sound environment in urban parks is often considered as "good" or "excellent" even if the sound pressure level is nearly always higher than the limits commonly used to define quiet areas. This is due to the influence of other factors, such as the presence of trees, natural features, and the tranquility; all of these components cannot be neglected in the assessment of the soundscape because they directly affect the psychological state of the person.
The use of straw in buildings has been common since the ancient times, but only at the beginning ... more The use of straw in buildings has been common since the ancient times, but only at the beginning of the twentieth
century, house made of straw bales were built in Nebraska. After a period of abandon, due mainly to the spread of
Portland concrete, this building technique has gained a new attention in the last decades, at least in a niche sector of
self-builders. Indeed, the main issue that an engineer or an architect must face when he/she decides to build a straw bale
house is the absence of certain data about the various technical performance. The aim of the present paper is to
investigate a straw bale wall, both in laboratory and in situ, and to perform a Life Cycle Assessment to identify strong
and weak points of this building technique. After a section reporting the state of the art of the main features of straw
bale constructions, including the most important physical parameters that affect durability and indoor comfort
conditions, the paper reports the results of laboratory measurements aimed at assessing the sound absorption coefficient
with an impedance tube and thermal conductivity with a guarded hot plate apparatus. Then, results of in-situ
measurements of thermal and sound insulation are reported. Data show that in winter (steady-state) conditions the
investigated wall offers adequate thermal insulation, but the lightness of the structure can be detrimental for the summer
(unsteady-state) season, leading to possible overheating in warm climates. Furthermore, the sound insulation is limited
by the lightness of the structure. Finally, the Life Cycle Assessment demonstrates that the use of straw bales in walls is
capable of reducing the energy and carbon embodied in the building.
In this paper the sound absorption properties of two types of plants for indoor applications are ... more In this paper the sound absorption properties of two types of plants for indoor applications are analyzed. The aim of this research is to investigate the feasibility of using Nephrolepis Exaltata (Boston Fern) and Helxine soleirolii (Baby Tears) in green walls for indoor applications, in order to improve the acoustic quality of indoor environments. The normal incidence sound absorption coefficient of ten specimens of Fern and three of Baby Tears was measured in presence and in absence of a substrate. The chosen substrate is made of coconut and perlite soil, commonly used in hydroponics; its composition allows to obtain high porosity values. The sound absorption coefficient spectra were measured in the frequency range of 50e1600 Hz using a vertically mounted impedance tube with a diameter of 100 mm; measurements were carried out in accordance with ISO 10534-2 method. After measuring the normal incidence sound absorption coefficient with impedance tube, the equivalent fluid model for sound propagation proposed by Miki was used to deduce non-acoustical properties of the samples. The inverted Miki's model allowed to find the theoretical tortuosity (a ∞) and the flow resistivity (s). These non-acoustic properties were then related to morphological characteristics of specimens. It is shown that the leaf area density is closely related to flow resistivity, at least for Boston Fern; the data allowed to identify a semi-empirical relation between them. Finally an application of the developed green system for the acoustic treatment of a real case study is reported.
Building insulation is commonly realized using materials obtained from petrochemicals (mainly pol... more Building insulation is commonly realized using materials obtained from petrochemicals (mainly polystyrene) or from natural sources processed with high energy consumptions (glass and rock wools). These materials cause significant detrimental effects on the environment mainly due to the production stage, i.e. use of non-renewable materials and fossil energy consumption, and to the disposal stage, i.e. problems in reusing or recycling the products at the end of their lives. The introduction of the concept of “sustainability” in building design process encouraged researches aimed at developing thermal and acoustic insulating materials using natural or recycled materials. Some of them, such as kenaf or wood fiber, are already commercialized but their diffusion
could be further improved since their performance is similar to the synthetic ones. Others are currently under study and their development is only at an early stage. The goal of the paper is to report a state of the art of building insulation products made of natural or recycled materials that are not or scarcely commercialized. Comparative analyses were carried out considering in particular thermal characteristics in terms of thermal conductivity, specific heat and density. Data on the acoustic performance of the materials were also reported. Life Cycle Assessment data were finally collected, in order to put in evidence the environmental advantages of these materials.
Particular attention was paid to researches focused to exploit local materials and even industrial byproducts, since these approaches respectively limit transportation and disposal impacts.
The energy consumption of a building is strongly dependent on the characteristics of its envelope... more The energy consumption of a building is strongly dependent on the characteristics of its envelope. The thermal performance of external walls represents a key factor to increase the energy efficiency of the construction sector and to reduce greenhouse gases emissions. Thermal insulation is undoubtedly one of the best ways to reduce the energy consumption due to both winter heating and summer cooling. Insulation materials play an important role in this scenario since the selection of the correct material, its thickness and its position, allow to obtain good indoor thermal comfort conditions and adequate energy savings. Thermal properties are extremely important, but they are not the only ones to be considered when designing a building envelope: sound insulation, resistance to fire, water vapor permeability and impact on the environment and on human health need to be carefully assessed too.
The purpose of the paper is to provide a review of the main commercialized insulation materials (conventional, alternative and advanced) for the building sector through a holistic and multidisciplinary approach, considering thermal properties, acoustic properties, reaction to fire and water vapor resistance; environmental issues were also taken into account by means of Life Cycle Assessment approach. A comparative analysis was performed, considering also unconventional insulation materials that are not yet present in the market. Finally a case study was conducted evaluating both thermal transmittance and dynamic thermal properties of one lightweight and three heavyweight walls, with different types of insulating materials and ways of installation (external, internal or cavity insulation).
Free access until July 8, 2016 at http://authors.elsevier.com/a/1T3UZ4s9HvmHxl
The historic urban centers often undergo redevelopment, restoration and enhancement activities ai... more The historic urban centers often undergo redevelopment, restoration and enhancement activities aimed at the preservation of the historical and artistic heritage and at the improvement of the citizens' quality of life. Usually these interventions are mainly focused on architecture and urban planning, favoring the visual appearance and not considering adequately the multidimensionality of the environment perception, not least the sound environment. For this reason, the choice to adopt the "Soundscape Approach" in the design is linked to the desire of adding a significant contribution to the regeneration of urban areas, in order to make them more enjoyable and to meet the needs of all the people who really and in different ways "live" the area (dwellers, storekeepers, tourists and night lifers). The case study of the present paper is located in the historical center of Perugia, in Italy. The acoustic analysis was performed through binaural recordings and soundwalks involving residents of the area, in order to obtain respectively objective and subjective evaluations of the soundscape. After this stage, Piazza Danti, a small square located in the very heart of the historical center, was chosen as the project area. This decision was taken together with the Municipality of Perugia since there are several problems afflicting the square, such as difficult routes for motorists, lack of urban design and, above all, nightlife noise. A comprehensive historical and architectural survey of the square allowed to understand all its morphological and functional characteristics, while a noise monitoring showed night noise levels significantly higher (even 30 dBA) than the law limits. These aspects guided the renovation project of the square: a particular focus was put on the interaction between the architectural and the soundscape design, in order to enrich the square with new sounds, while reducing some noise issues considered highly annoying by part of the citizens.
Gli infissi ventilati antirumore rappresentano una soluzione innovativa per la protezione degli e... more Gli infissi ventilati antirumore rappresentano una soluzione innovativa per la protezione degli edifici dall'inquinamento acustico. Tali tipologie di finestre, oltre ad essere caratterizzate da elevate prestazioni di isolamento acustico, permettono un ricambio d'aria all'interno degli appartamenti attraverso aeratori insonorizzati e sono dotate di un cassonetto insonorizzato per l'alloggiamento dell'avvolgibile.
The paper concerns the use of granulated polymeric materials obtained from sheaths of electric wi... more The paper concerns the use of granulated polymeric materials obtained from sheaths of electric wires, mixed with concrete and water to produce under-floors with good sound and thermal insulating performance. This is a possible solution for the re-use of this typology of waste, so to avoid the disposal into landfills. Several configurations of the product were tested in the reverberation rooms of the Laboratory of Acoustics according to ISO 140-6 and ISO 140-8 standards, in order to fully characterize the sound insulating properties; the thermal conductivity was measured through the hot box of the Laboratory of Thermotechnics, according to EN 1934. Also mechanical tests were executed in terms of dynamic stiffness according to ISO 9052-1 and compressibility according to EN 12431; a chemical analysis completes the investigation of the mixture. The results show that the product presents satisfying thermal performance, together with good mechanical properties; the chemical analysis of the loose polymers underlined the presence of some chlorinated and polycyclic hydrocarbons. From the acoustic point view, the sound impact reduction index directly evaluated both with a direct test on the reverberation room and with the indirect estimations through the dynamic stiffness gave results comparable with common materials used for screeds. When the material was tested in conjunction with other typical components of floors, the sound impact reduction index showed poorer performance, underlining that the optimization of the acoustic properties has to be done taking into account the combination with other floor materials. a Email address: [email protected] b
The European standard EN ISO 140-12:2000 gives a methodology to measure the acoustic performance ... more The European standard EN ISO 140-12:2000 gives a methodology to measure the acoustic performance of access floors in terms of both airborne and impact sound insulation. Access floors are often used in office buildings and working environments as they create a hollow space below the floor surface for network cabling and electrical wiring: in this way they are useful from the functional (ease of inspection, repair and changing of system elements), the aesthetic (no exposed wires and elements) and acoustic point of view. This paper presents the measurement procedures used at the Acoustic Laboratory of the University of Perugia -Italy, in order to perform the tests defined by the EN ISO 140-12. The standard requires the measurement of two parameters, L n,f e D n,f , that qualify respectively the airborne and the impact sound insulation trough an access floor, and the calculation of the two corresponding single number indexes L n,f,W e D n,f,W . A sample of access floor has been tested in the purposely prepared reverberating rooms of the Laboratory, with and without covering. Particular attention has been paid to test rooms set up and to sample installation because of the complexity of these phases.
This paper reports the design process for the redevelopment of a square located in the historical... more This paper reports the design process for the redevelopment of a square located in the historical center of Città di Castello, central Italy. The square is currently used as a parking lot for the residents; this has completely compromised the beautiful Renaissance paving. Town Planning Schedule will soon turn the space into a pedestrian area; furthermore the Public Library will be located in a building facing the square. The goal of the design is to redevelop the square, and in particular the design idea is to convert the square into an outdoor floor for the Public Library, to be used both for individual reading/studying and for conferences and cultural events. The current visual and acoustical status of the area are firstly described. Binaural recordings were carried out to measure the acoustical climate and soundwalks were conducted to detect the soundmarks of the area. Moreover, a questionnaire survey was conducted in the current Public Library in order to collect data on the design options for the open space of the new library. The results of the acoustic measurements and of the surveys allowed to redesign the square both from architectural and soundscape point of view.
ISO 140-5 defines the procedures to evaluate the sound insulation of façades obtaining the global... more ISO 140-5 defines the procedures to evaluate the sound insulation of façades obtaining the global value D 2m,nT,w . Moreover, each component of the façade can be characterized in laboratory by means of its airborne sound insulation R using the methodology given by ISO 10140, and the weighted sound reduction index R W calculated using ISO 717-1. It is possible to deepen the analysis of the façade components behavior using sound maps obtained through sound intensity measurements. These are used to locate sound leakages and, in general, to have a clear view of the performance of the tested element sub-components. The paper, after a brief description of the method and the instruments used, presents the results of several campaigns executed on different moveable parts of a building's envelope: windows, doors and minor components such as rolling shutter boxes. Thanks to the various case-studies presented, it is demonstrated how the sound intensity measurements -using P-P probes -could bring to not negligible improvements both on the design and the installation of the investigated components. Finally, a different technique for measuring sound intensity passing through a window is presented, using a P-U (Pressure -Velocity) probe.
The paper concerns the use of granulated polymeric materials obtained from sheaths of electric wi... more The paper concerns the use of granulated polymeric materials obtained from sheaths of electric wires, mixed with concrete and water to produce under-floors with good sound and thermal insulating performance. This is a possible solution for the re-use of this typology of waste, so to avoid the disposal into landfills. Several configurations of the product were tested in the reverberation rooms of the Laboratory of Acoustics according to ISO 140-8 standard, in order to fully characterize the sound insulating properties; the thermal conductivity was measured through the hot box of the Laboratory of Thermotechnics, according to EN 1934. Also mechanical tests were executed in terms of dynamic stiffness according to EN 29052-1 and compressibility according to EN 12431; a chemical analysis completes the investigation of the mixture. The results show that the product presents satisfying thermal performance, together with go od mechanical properties; the chemical analysis of the loose polymers underlined the presence of some chlorinated and polycyclic hydrocarbons. From the acoustic point of view, the sound impact reduction index directly evaluated both with a direct test in the reverberation room and with the indirect estimations through the dynamic stiffness gave results comparable with common materials used for screeds. When the material was tested in conjunction with other typical components of floors, the sound impact reduction index showed poorer performance, underlining that the optimization of the acoustic properties has to be done taking into account of the combination with other floor materials.
A significant number of Life Cycle Assessment (LCA) analyses of renewable energy technologies is ... more A significant number of Life Cycle Assessment (LCA) analyses of renewable energy technologies is available in the literature, even though there is a lack of consistent conclusions about the life cycle impacts of the different technologies. The reported results vary consistently, according to the size and the technology of the considered plant, thus limiting the utility of LCA to inform policy makers and constituting a barrier to the deployment of a full awareness on sustainable energies. This variability in LCA results, in fact, can generate confusion regarding the actual environmental consequences of implementing renewable technologies. The paper reviews approximately 50 papers, related to more than 100 different case studies regarding solar energy (Concentrated Solar Power, Photovoltaic), wind power, hydropower and geothermal power. A methodology for the harmonization of the results is presented. The detailed data collection and the results normalization and harmonization allowed a more reliable comparison of the various renewable technologies. For most of the considered environmental indicators, wind power technologies and PV technologies turn out to be respectively the low end and the high end of the impact range where all the other technologies are positioned.
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Papers by Francesco D'Alessandro
century, house made of straw bales were built in Nebraska. After a period of abandon, due mainly to the spread of
Portland concrete, this building technique has gained a new attention in the last decades, at least in a niche sector of
self-builders. Indeed, the main issue that an engineer or an architect must face when he/she decides to build a straw bale
house is the absence of certain data about the various technical performance. The aim of the present paper is to
investigate a straw bale wall, both in laboratory and in situ, and to perform a Life Cycle Assessment to identify strong
and weak points of this building technique. After a section reporting the state of the art of the main features of straw
bale constructions, including the most important physical parameters that affect durability and indoor comfort
conditions, the paper reports the results of laboratory measurements aimed at assessing the sound absorption coefficient
with an impedance tube and thermal conductivity with a guarded hot plate apparatus. Then, results of in-situ
measurements of thermal and sound insulation are reported. Data show that in winter (steady-state) conditions the
investigated wall offers adequate thermal insulation, but the lightness of the structure can be detrimental for the summer
(unsteady-state) season, leading to possible overheating in warm climates. Furthermore, the sound insulation is limited
by the lightness of the structure. Finally, the Life Cycle Assessment demonstrates that the use of straw bales in walls is
capable of reducing the energy and carbon embodied in the building.
could be further improved since their performance is similar to the synthetic ones. Others are currently under study and their development is only at an early stage. The goal of the paper is to report a state of the art of building insulation products made of natural or recycled materials that are not or scarcely commercialized. Comparative analyses were carried out considering in particular thermal characteristics in terms of thermal conductivity, specific heat and density. Data on the acoustic performance of the materials were also reported. Life Cycle Assessment data were finally collected, in order to put in evidence the environmental advantages of these materials.
Particular attention was paid to researches focused to exploit local materials and even industrial byproducts, since these approaches respectively limit transportation and disposal impacts.
The purpose of the paper is to provide a review of the main commercialized insulation materials (conventional, alternative and advanced) for the building sector through a holistic and multidisciplinary approach, considering thermal properties, acoustic properties, reaction to fire and water vapor resistance; environmental issues were also taken into account by means of Life Cycle Assessment approach. A comparative analysis was performed, considering also unconventional insulation materials that are not yet present in the market. Finally a case study was conducted evaluating both thermal transmittance and dynamic thermal properties of one lightweight and three heavyweight walls, with different types of insulating materials and ways of installation (external, internal or cavity insulation).
Free access until July 8, 2016 at http://authors.elsevier.com/a/1T3UZ4s9HvmHxl
century, house made of straw bales were built in Nebraska. After a period of abandon, due mainly to the spread of
Portland concrete, this building technique has gained a new attention in the last decades, at least in a niche sector of
self-builders. Indeed, the main issue that an engineer or an architect must face when he/she decides to build a straw bale
house is the absence of certain data about the various technical performance. The aim of the present paper is to
investigate a straw bale wall, both in laboratory and in situ, and to perform a Life Cycle Assessment to identify strong
and weak points of this building technique. After a section reporting the state of the art of the main features of straw
bale constructions, including the most important physical parameters that affect durability and indoor comfort
conditions, the paper reports the results of laboratory measurements aimed at assessing the sound absorption coefficient
with an impedance tube and thermal conductivity with a guarded hot plate apparatus. Then, results of in-situ
measurements of thermal and sound insulation are reported. Data show that in winter (steady-state) conditions the
investigated wall offers adequate thermal insulation, but the lightness of the structure can be detrimental for the summer
(unsteady-state) season, leading to possible overheating in warm climates. Furthermore, the sound insulation is limited
by the lightness of the structure. Finally, the Life Cycle Assessment demonstrates that the use of straw bales in walls is
capable of reducing the energy and carbon embodied in the building.
could be further improved since their performance is similar to the synthetic ones. Others are currently under study and their development is only at an early stage. The goal of the paper is to report a state of the art of building insulation products made of natural or recycled materials that are not or scarcely commercialized. Comparative analyses were carried out considering in particular thermal characteristics in terms of thermal conductivity, specific heat and density. Data on the acoustic performance of the materials were also reported. Life Cycle Assessment data were finally collected, in order to put in evidence the environmental advantages of these materials.
Particular attention was paid to researches focused to exploit local materials and even industrial byproducts, since these approaches respectively limit transportation and disposal impacts.
The purpose of the paper is to provide a review of the main commercialized insulation materials (conventional, alternative and advanced) for the building sector through a holistic and multidisciplinary approach, considering thermal properties, acoustic properties, reaction to fire and water vapor resistance; environmental issues were also taken into account by means of Life Cycle Assessment approach. A comparative analysis was performed, considering also unconventional insulation materials that are not yet present in the market. Finally a case study was conducted evaluating both thermal transmittance and dynamic thermal properties of one lightweight and three heavyweight walls, with different types of insulating materials and ways of installation (external, internal or cavity insulation).
Free access until July 8, 2016 at http://authors.elsevier.com/a/1T3UZ4s9HvmHxl