Using natural phenomena to reach indoor comfort has been known since early time and the oldest heritage architecture‘s and engineering of Middle East region, which has responded with such phenomena as well very good solutions special for hot-dry region (height temperature and radiation at summer and big variation between day and night temperature also between the hot summer and cool winter). This Architecture realized inside its houses optimum comfortable temperatures throughout nearly all the days of the yearlong. That was through equating with the volume adopting and the space taming with the different natural elements forces of the sun, atmosphere and climate as all which is common in these days as passive design strategies and reducing energy consumption . This research investigate the thermal mass and natural ventilation for traditional house (hot-dry region in Damascus) that gives high energy efficiency in providing cool indoor air through ventilation (single sided , cross ventilation) and envelope behavior, with the procedures of measurements combined with simulation program model, to improve Middle East new residential buildings through utilize combination of passive cooling and heating techniques. Natural ventilation in traditional building coupled with effects of massive construction and design assemble, provide thermal comfort (temperature control) over interior condition. This strategies are utilized to conserve energy in a hot-dry climate specially on middle east region as Damascus and other cities which have comfort traditional houses . The modern template applied by simulation program for traditional heating and cooling technique achieves thermal comfort related to occupant behavior and reduces energy consumption for new apartment of about 30-45% reduction of energy needs at Damascus, 20-35% at Cairo and 15-30% also at very hot dry climate as Riyadh.

The present work explores the theoretical basis of sound propagation through periodic media and provides experimental evidences of stop-band properties of sonic crystals, periodic arrays of scatterers immersed in air. In order to investigate the sound field generated by sonic crystals, three theoretical models are used. The band structures are analysed with the Plane Wave Expansion method, while the Multiple Scattering Theory is used to calculate the magnitude of the scattered sound field. The Finite Element analysis is used for both purposes and to provide a stronger bond between the calculations of the theoretical models and the experimental results. Experimental measurement campaigns are performed at the Open University, Milton Keynes (UK) and at the University of Bologna. The two laboratories offer different testing facilities, respectively an anechoic chamber and a large industrial hall. Three square unit cells are analysed, varying the lattice constant and/or the filling fraction in order to provide a correlation between the two experimental setups. Measurements are performed to assess the characteristics of the sound field transmitted and reflected from the arrays, posing a special attention to the contribution of side and top edge diffraction. The evanescent behaviour of modes inside the lattice has been investigated by carrying out Impulse Response measurements inside the crystal and testing, with an intensity probe, the components of the sound field that exit the crystal in the two main directions. Finally, standardised indices are calculated that allow to compare the screening performance of sonic crystals to those of common noise barriers. All measurements setups report coherent results among them and with respect to the theoretical calculations, representing a solid platform for further developments.

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L’attività di ricerca del dottorando è stata rivolta allo studio della trasmissione del rumore per via strutturale negli edifici. Questo argomento e' di notevole interesse sia fondamentale che applicativo. Il fenomeno e le problematiche ad essa connesse contribuiscono alla diminuzione delle prestazioni fonoisolanti, sia per le strutture verticali (usualmente valutate rispetto al rumore aereo), sia per quelle orizzontali (valutate anche rispetto al rumore impattivo) ed è tipico degli edifici con struttura portante a telaio e tamponatura in laterizi. Si tratta delle tipiche tipologie edilizie italiane, per le quali il problema risulta amplificato rispetto ad altre tipologie. La metodologia di studio è stata di tipo sperimentale. La scelta è dettata sia dall’insufficiente avanzamento dello stato dell’arte dei metodi di calcolo teorici, o delle loro versioni numeriche, sia dalla necessità di disporre di dati certi da confrontare con i valori forniti dai metodi previsionali semplificati indicati nelle norme UNI (modello CEN); infatti queste ultime sono un recepimento letterale di quelle europee, sebbene esse si basino su tipologie costruttive, materiali e tecniche di realizzazione differenti da quelle comunemente in uso in Italia; da qui la difformità di risultati tra formule previsionali e misurazioni sperimentali. Al fine di realizzare uno studio completo delle principali casistiche della trasmissione laterale sono state utilizzate 6 configurazioni in scala reale, con elementi edilizi diversamente collegati fra loro in modo da simulare i nodi strutturali comunemente realizzati negli edifici. La parte sperimentale della ricerca è stata svolta presso le “Camere Acustiche di Prova” del Laboratorio del Lazzaretto “R. Alessi” del DIENCA. Oltre alle usuali misurazioni di isolamento acustico, sono state eseguite numerose misurazioni di vibrazione. Infatti, dal confronto dei livelli di velocità di vibrazione dei diversi elementi di una struttura, rigidamente connessi, è possibile determinare l’indice di riduzione delle vibrazioni Kij che è la grandezza chiave per modellizzare il fenomeno della trasmissione laterale. La possibilità di determinare sperimentalmente tali valori nel contesto di un lavoro di ricerca finalizzato a determinare i meccanismi di propagazione delle vibrazioni nelle strutture, permette di valutare la precisione delle formule previsionali del modello CEN e di proporne varianti e integrazioni. I valori di Kij così determinati assumono grande importanza anche in fase di progetto, fornendo dati attendibili da utilizzare per la progettazione acustica degli edifici.

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No description available.

The general aim of this work is to contribute to the energy performance assessment of ventilated façades by the simultaneous use of experimental data and numerical simulations. A significant amount of experimental work was done on different types of ventilated façades with natural ventilation. The measurements were taken on a test building. The external walls of this tower are rainscreen ventilated façades. Ventilation grills are located at the top and at the bottom of the tower. In this work the modelling of the test building using a dynamic thermal simulation program (ESP-r) is presented and the main results discussed. In order to investigate the best summer thermal performance of rainscreen ventilated skin façade a study for different setups of rainscreen walls was made. In particular, influences of ventilation grills, air cavity thickness, skin colour, skin material, orientation of façade were investigated. It is shown that some types of rainscreen ventilated façade typologies are capable of lowering the cooling energy demand of a few percent points.

The Schroeder's backward integration method is the most used method to extract the decay curve of an acoustic impulse response and to calculate the reverberation time from this curve. In the literature the limits and the possible improvements of this method are widely discussed. In this work a new method is proposed for the evaluation of the energy decay curve. The new method has been implemented in a Matlab toolbox. Its performance has been tested versus the most accredited literature method. The values of EDT and reverberation time extracted from the energy decay curves calculated with both methods have been compared in terms of the values themselves and in terms of their statistical representativeness. The main case study consists of nine Italian historical theatres in which acoustical measurements were performed. The comparison of the two extraction methods has also been applied to a critical case, i.e. the structural impulse responses of some building elements. The comparison underlines that both methods return a comparable value of the T30. Decreasing the range of evaluation, they reveal increasing differences; in particular, the main differences are in the first part of the decay, where the EDT is evaluated. This is a consequence of the fact that the new method returns a “locally" defined energy decay curve, whereas the Schroeder's method accumulates energy from the tail to the beginning of the impulse response. Another characteristic of the new method for the energy decay extraction curve is its independence on the background noise estimation. Finally, a statistical analysis is performed on the T30 and EDT values calculated from the impulse responses measurements in the Italian historical theatres. The aim of this evaluation is to know whether a subset of measurements could be considered representative for a complete characterization of these opera houses.

Air-source heat pumps coupled with photovoltaic systems are going to be a more and more promising technology, as its widespread application in residential houses will help achieving the decarbonisation of the building sector, which is strongly promoted by the European Union. The aspects that inspire confidence for this solution are that: i) the average quality of heat pumps has recently improved; ii) new and renovated buildings, with well insulated envelopes, are more suitable for low-temperature heating systems; iii) photovoltaic modules price is significantly decreased and still shows a diminishing trend; iv) the share of the electricity production from renewable sources is progressively increasing, making the use of electricity more ecologically favourable and v) heat pump and photovoltaic systems can make the residential sector flexible and ready to face the changes in the electricity system. The aim of this thesis is to analyse the manifold relationships between the building, the HVAC system and the boundary conditions, as well as the interaction of this system with the electricity grid. The work is almost entirely based on the dynamic simulation, which is performed by using more or less detailed models, depending on the objective of the single study. The heat pump is a crucial element, since its behaviour is influenced by many factors. Therefore, particular attention is pointed toward the modelling of this component and its control. The general approach mainly adopted is the comparison between a reference system, defined case by case, and other similar scenarios in which one or more variations are introduced. Since different aspects are investigated, the variations can concern either the system component (building and HVAC system), the boundary conditions or the control strategy. In particular, one of the studies provide an extensive analysis on how the climate impacts the behaviour of the system, involving nine European cities in a wide range of latitude. The role of the thermal storage (water tank and building thermal mass) is also studied, showing that its potential is exploited only when it is properly controlled. The last part of the thesis focuses on the system control, which influences the system performance more than expected. Despite this, the benefits of applying the proposed smart control strategies are not as great as those deriving from the addition of the electrical storage, in a system in which only the thermal storage is present. Even better results can be obtained by applying control strategies that also manage the battery charging/discharging. A general conclusion is that rule-based control strategies would be cheap and e↵ective; however, they require a tailored implementation and their development for the mass-market is not easy.

The technologies for the use of biomass as an energy source are not always environmental friendly process: wood combustion, for example, can be a rather a dirty process that causes the release in air of several dangerous compounds. For those reasons it is important to develop approaches aimed at the use of biomass in a cleanest way, avoiding, whenever possible, direct combustion of solid biomass and, rather, pursuing fuel upgrade processes allowing a better combustion or direct conversion to electricity through fuel cells. The products originating from the gasification process mainly comprise a mixture of the permanent gases CO, CO2, H2 and CH4, steam, char, tars and ash. The raw synthesis gas needs to be cleaned from tars before it may be upgraded to other commodities. In most cases if tars deposit on the catalyst surface it will block the active sites i.e., carbon acts as catalyst poison. Furthermore, tars in the raw gas can also cause corrosion and blockage of pipes in downstream process equipment. One of the main challenges in biomass gasification is the minimization of tar content in the product gas in combination with optimization of the gas composition. That is, to reduce the tar content as much as possible and to increase the permanent gases. In this context, it is especially interesting the development of technologies for syngas production (i.e. synthesis gas) through biomass gasification and for syngas utilization in fuel cells system, in order to produce energy from renewable resources. In detail the SOFCs (Solid Oxide Fuel Cell) work at high temperatures, and can be fed with different type of fuels, such as methane, carbon monoxide and hydrogen. Thus, the syngas produced by means of biomass gasification, seems to be a suitable fuel for this kind of cells. This chance is particularly interesting, considering that small and medium size conversion plant technologies could be integrated in a distributed energy generation model that is expected to increase its diffusion. The aim of the present project is to verify the possibility of coupling a biomass gasifier with a SOFC for energy production. The use of steam as gasifying agent increases the syngas heating value in comparison with the use of air, since its nitrogen content cause a dilution of the obtained gaseous fuel. Moreover, another beneficial effect in using water steam, is the increase of the H2 percentage up to 50 % in volume. A high hydrogen concentration is kindly recommended if the final aim is to feed a fuel cell. However, the disadvantages of the steam gasification are the lower steam reactivity, comparing with the oxygen one, and the decreasing of the temperature inside the reactor due to the endothermicity of the main reactions. Thus, it is necessary to supply indirectly the heat of reaction. In fluidized bed gasifiers, the bed material acts as solid heat carriers and often provides the heat from char combustion; however fixed bed gasifier are more suitable for small scale application, especially when biomass is used as feedstock . In the first part of this project a small scale (semi continuous, fixed-bed) gasifier has been designed and built. The syngas composition produced has been analyzed and the hydrogen concentration was approximately 60%. In a second stage the plant has been modified in a continuous fixed-bed gasifier, to perform long test duration. The gas composition slightly changes, even if anyway exploitable in fuel cell. Between the gasifier and the fuel cell, a gas cleaning stage has been foreseen. A catalyst is needed for tar cracking. A series of air-gasification tests have been run in a fluidized bed gasifier to test two different catalysts: dolomite and iron. The results on tar concentrations have confirmed the higher efficiency of dolomite in tar cracking. Then, a catalytic filter filled with dolomite has been placed after the fixed bed gasifier for tar abatement. Finally, some tests coupling the gasifier with a solid oxide fuel cells stack have been run. The temperature field measured during the experimental activity by some K-thermocouples has been elaborated to estimate an apparent thermal conductivity coefficient to be used in a 2D model for heat transfer simulation; moreover the data on the syngas composition have been used to test the reliability of a thermo chemical equilibrium model previously developed. The agreement between the output of the equilibrium model and the experimental data is not satisfying. The main problems are the prediction of the residual solid carbon phase and the methane estimation. It is known that the methane prediction it is a difficult task, because it is mainly formed by tars cracking, and thus it is not an equilibrium compound. Several authors have already faced the problem of methane estimation modifying the model with different approaches. In this work, the experimental data have been used to tune up the model, considering the residual solid carbon formed by means of the definition of a parameter called “carbon conversion efficiency†. The accuracy between the thermodynamic equilibrium model and the experimental values significantly improves if the percentage of solid phase is considered. A second modification has been introduced to take into account the moles of carbon and hydrogen which contribute to the methane formation. A better agreement between the experimental results and the output of the modified model has been observed. The experimental campaign shows that steam gasification represents an interesting pathway for the biomass utilization, because it leads to a high quality effluent gas, suitable for feeding solid oxide fuel cells. The proposed modified equilibrium model seems to be a useful engineering tool, as the syngas composition measured is not so far from the thermodynamic predictions.