1,720,987 research outputs found
ASSESSMENT AND COMPARISON AMONG PREDICTION METHODS FOR THE LOW FREQUENCY NOISE PRODUCED BY WIND TURBINES: APPLICATION TO A CASE STUDY
No full textThe present energy scenario leads to an acceleration in the development of the exploitation of renewable sources. Latest regulations impose higher and higher percentage shares of energy from renewable sources. The current technological advancement stresses the wind energy as an energy source endowed of a special reliability. The technology to take advantage of such a source is based on large size wind turbines, with a rated power of about 3 MW.
Among the main environmental problems that have to be faced in planning a new wind farm, the acoustic impact stands out. It consists of noise engendered by wind turbines with a special effect of noise emitted at the low frequency spectrum. Recently Denmark has produced a new regulation which calls for specific procedures for the assessment of noise at low frequencies.
Purpose of the present work is to take stock of the procedures currently employed in the predictive study of the low frequency noise produced by wind turbines. The analysis was carried out by applying the expounded procedures to a real case situated in Sardinia. It concerns a wind farm formed with 21 large size turbines, where a comparison between the results obtained by applying the procedures of ISO 9613 and those provided for by the Danish regulation is shown
Redevelopment and Sustainability. Scenarios for the Reuse and Conservation of Historical Prisons
No full textAmong the actions to achieve the objectives set by the European Union in the "Fit for 55 Package" which sets a target of reducing net emissions of climate-altering gases by 55% by 2030, includes the EPBD Directive, with the aim of identifying and redevelop buildings with inadequate energy performance. The architectural assets subject to protection restrictions and the "complexes of immovable things that make up a characteristic aspect having an aesthetic and traditional value" remain outside the scope of application. In Italy, most of the historic buildings fall under this definition and among these the now abandoned prison structures, characterized by very high historical and architectural value but often left unused, spread practically throughout the national territory. Several local authorities introduced rules and prescriptions for the energy efficiency of the envelope into their regulations, but these remain applications limited to the local context, unable to give a universally valid procedure for the vast cultural heritage. The sporadic initiatives carried out up to now constitute a valid testimony on the possibility of overcoming the problems connected to the change in the use of the existing building. Starting from these successful cases, and not only at a national level, this research aims to provide a methodology for analyzing the existing and the today available “bacs”, to support the design process for the reuse of these historic buildings. The proposed approach is based on environmental sustainability and tries to highlight those design choice parameters capable of solving the problems of integration with historical construction materials and ancient techniques constructive, overcoming the gap between the needs of the historical buildings and the available solutions
INFLUENZA SUGLI INDICI DI VALUTAZIONE DEI REQUISITI ACUSTICI PASSIVI IN SITU DELLA MISURA DEL TEMPO DI RIVERBERAZIONE
No full textA diversi anni dall’entrata in vigore del DPCM 5\12\97 si verificano sempre più casi di contenzioso fra venditore ed acquirente, talvolta basate su risultati differenti ottenuti in situ, nelle misure fatte eseguire dalle parti in causa. Il presente lavoro valuta come la misura del tempo di riverberazione in opera, eseguita in uno stesso ambiente, con l’utilizzo delle metodologie di misura basate sul rumore interrotto o sul rumore impulsivo, incida sugli indici di valutazione dei requisiti acustici passivi a seconda della tipologia di sorgenti utilizzate
Heating and cooling loads with electrochromic glazing in Mediterranean climate
No full textThe energy consumption necessary to maintain thermal comfort in buildings remains a significant and partially unjustified part, accounting for about 30–40% of the total energy consumption. Despite the increasingly pressing regulations in the energy sector (EPBD recast), the quality of the internal environment remains one of the critical parameters on which to pay more attention in view of a consistent evaluation of the Nzeb building. The windowed components are often designed with thermal insulation performances higher than the minimum requirements but still they lack in design of the incident solar radiation control, which is a particularly delicate topic for indoor comfort and more generally for a higher energy efficiency in buildings. If we think of the numerous variables of influence (typology, orientation, geographical location, etc.), the possibilities to associate energy saving, lighting control and users’ comfort are inevitably entrusted to dynamic systems integrated into the glass. In this paper authors present the results related to the experimental characterization of two identical test rooms with different typologies of windows. One room is furnished with a traditional high thermal performance glass and the other, with an electrochromic glass suitably controlled by remote. The operative temperature measured in both test rooms have been utilized to verify the simulation model developed to assess the energy saving achievable in a Mediterranean climate, taking properly into account the hourly variations of the climate and the actions on the shading regulation systems
An Adaptive Neural Network model for thermal characterization of building components
Full text linkBuilding materials are usually characterized in stationary or almost-stationary conditions and mono dimensional heat flow regime. The existing standards (such as ISO 9869 or EN ISO 6946, EN 12664, EN 12667, ISO 8302 etc), require experiments carried out in steady-state conditions, with a very fine control of the measuring parameters with the aim to apply a simple and reproducible procedure for the determination of thermal properties. However, the thermodynamic conditions that lead to a steady-state operating mode and mono dimensional flow are very difficult to obtain (in real conditions) or very expensive and time consuming (in climate chambers). In this paper the authors present the development of a method for thermal characterization of building components, inferring the steady-state conditions, when only measures in transient conditions are available. The method, based on an adaptive linear neural network (ALNN) model also could be have the potentialities to determine the thermal diffusivity from a significant transient behavior ad hoc imposed. The study targets multilayered walls homogeneous and the results are compared with the experimental data measured by a climate chamber that operate according to the standard EN 12667
BIM Process for acoustic problems
No full textRecent communications from the European Community oblige Member States to use the BIM (Buildilg Information Modeling) in the realization of public works. At European level countries like the United Kingdom, Sweden, Holland and Denmark have already used BIM models for the management of the built heritage for several years. At extra-European level China, the USA and in particular Singapore have long taken the road to digitization of buildings and more generally of the built heritage. What drives to digitalization is saving money that these digital procedures allow in the different phases of life of buildings. The present work wants to do an overview of the use of Open Source BIM models regarding the management of acoustic problems, both for the acoustic performance of buildings and from the point of view of environmental acoustics. In the work the main open source data formats available today, such as IFC and CityGML, some of which are recognized as standard from ISO. The data concerning the acoustic issues present in the various formats will also be analyzed and one Data Template will be proposed for the lack of parts or missing according to the provisions of the various international standards
Comparison between calculated and measured performances of impact sound insulation for Cross Laminated Timber building elements
No full textThe use of simplified prediction models described in the EN 12354 series standard is largely diffused and suggested or adopted in many building codes. The aim of this work is to evaluate the reliability of calculation methods of impact sound insulation by comparison with in situ measurements. A case study about buildings made with Cross Laminated Timber (CLT) elements is presented
CONFRONTO FRA PRESTAZIONI ACUSTICHE PASSIVE PREVISIONALI E MISURAZIONI IN OPERA DEL RUMORE DA CALPESTIO NEI SOLAI ORTOTROPICI IN LATERIZIO E CEMENTO IN CONFIGURAZIONI GEOMETRICHE COMPLESSE
No full textIl presente lavoro tratta il confronto fra le prestazioni previsionali relative
al rumore da calpestio di solai in laterizio e cemento e le prestazioni misurate in opera inerenti le configurazioni geometriche complesse di questa tipologia di partizioni. Le
misurazioni sono state effettuate in edifici di nuova costruzione in Sardegna, con elementi
costruttivi in parte specifici. I risultati previsionali ottenuti sono stati infine confrontati con
le curve e gli indici ottenuti a seguito di una campagna di misurazioni in opera in cui
sono state sottoposte a verifica oltre venti configurazioni complesse. Il presente lavoro si articola in più fasi, a cui si farà poi riferimento nel prosieguo e di seguito brevemente riportate:
-Fase 1- Rilievo in opera del livello di pressione sonora L’n del solo solaio strutturale in
laterizio e cemento per le cinque configurazioni complesse riportate in figura 1 cosi come
fatto da Di Bella ed altri [5] e confronto dei risultati con la curva di riferimento per i
solai in laterizio e cemento secondo quanto riportato da Di Bella ed altri [2] e Semprini
ed altri [3];
-Fase 2 –Analisi e descrizione del pavimento galleggiante utilizzato nel caso studio costituito
da oltre cinquanta unità immobiliari;
-Fase 3 –Calcolo previsionale delle prestazioni dei solai da sottoporre a verifica tramite
l’utilizzo della curva definita da Di Bella e altri [2], Semprini ed altri [3] Schiavi ed altri
[5];
-Fase 4 –Misurazioni in opera delle prestazioni delle partizioni in differenti configurazioni:
ultimate con strato di finitura in ceramica e in legno, da ultimare cioè non dotate
dello strato di finitura ma con il massetto galleggiante già posato;
-Fase 5 –Confronto dei risultati ottenuti a seguito delle misurazioni in opera con i risultati
ottenuti per le stesse partizioni in via previsionale
Comparison between calculated and measured performances of impact sound insulation for Cross Laminated Timber building elements
No full textThe use of simplified prediction models described in the EN 12354 series standard is largely
diffused and suggested or adopted in many building codes. The aim of this work is to evaluate the
reliability of calculation methods of impact sound insulation by comparison with in situ
measurements. A case study about buildings made with Cross Laminated Timber (CLT) elements
is presented
Evaluations about the acoustic insulation of facade for different construction categories, as calculated by means of the prediction model encoded in EN 12354 and after in situ measurements on buildings in the Mediterranean area
No full textIn the present work the acoustic insulation of facade is dealt with, starting from the prediction
calculations regarding the assessments for case studies, according to EN 12354 procedures, to go on with the comparisons with in situ measurements carried out at accomplished construction.
In detail different building types have been analyzed, i. e. structures in reinforced concrete
with infill walls, as well as structures in cross laminated timber and structures in bearing
wall realized in Sardinia. In the paper the effect of small elements on acoustic insulation is
evaluated apart from the comparison of the performance for different construction types
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