1,720,997 research outputs found
Prestazione termoenergetica di edifici sostenibili in terra cruda
No full textSi riportano i risultati di una campagna di misure su intonaci di terra cruda mista a paglia d’orzo in differenti percentuali. I valori dei parametri termoigrometrici ottenuti portano a ritenere tale materiale più idoneo, rispetto ad altri materiali da intonaco, a mitigare le condizioni termoigrometriche degli ambienti confinati.
A tale fine è stato utilizzato il software WUFI+ per una analisi dettagliata delle condizioni termoigrometriche in un monolocale campione realizzato con pareti laterali e soffitto rivestiti con intonaco di terra cruda-paglia. La prestazione termoigrometrica è stata confrontata con quella dello stesso locale in presenza di intonaco di gesso. Il confronto tra le due soluzioni è stato condotto nelle due situazioni di: a) edificio passivo, in assenza di impianto di climatizzazione; b) edificio con impianto di condizionamento in grado di mantenere condizioni interne di temperatura ed umidità controllate tutto l’anno.
L’analisi dei risultati della simulazione ha portato alla conclusione che l’adozione dell’intonaco in terra cruda alleggerita con il 4% di paglia realizza condizioni igrometriche interne migliori con un più intenso scambio di flusso di vapore d’acqua tra le superfici interne e l’aria interna. Inoltre, in presenza dell’impianto di condizionamento, il consumo energetico per la umidificazione-deumidificazione dell’aria ambiente è più ridotto per la soluzione di intonaco in terra-paglia.Results of measurements on plaster of unbaked earth with different percentages of barley straw are reported. Values of hygrothermal parameters lead us to believe the material more suitable than other plasters, to mitigate the humidity of confined spaces.
WUFI+ simulations were carried out for a detailed analysis of temperature and humidity conditions in a sample room with side walls and ceiling with unbaked earth-straw plaster. Hygrothermal performance was compared with the same room with gypsum plaster. The comparison between the two solutions was carried out in two situations: a) passive building, without air conditioning, b) building with air conditioning system able of maintaining internal conditions with controlled temperature and humidity all year round.
Results pointed out that plaster of unbaked earth with 4%b.w. of barley straw gives rise to better indoor conditions in terms of humidity with a more intensive exchange of water vapor flux between inner surfaces and indoor air. Moreover, in the presence of air conditioning system, energy consumption for air humidification-dehumidification is less expensive for the unbaked earth-straw plaster
Experimental study on hygrothermal performances of indoor covering materials
No full textSeveral clayey materials were prepared in Thermophysical Laboratory of Bari. Hygrothermal properties were measured according to technical standards. In order to consider the potential of earthen materials to improve indoor comfort, the software WUFI+ was used to simulate the hygrothermal behavior of a Test Room, placed in a Mediterranean climate. The analysis was carried out considering the internal surface of the walls of the building covered by five different plasters. Results demonstrated that when considering an unconditioned scenario (without HVAC system) Clay-Straw and Lime-Bentonite lead up to a greater improvement of the hygric performances, unlike traditional coverings as Gypsum or Ceramic tiles. It can be appreciated a greater damping relative humidity and sorption capacity of the earthen coatings. However, in presence of HVAC system any significant variations occurs in terms of energy saving
Research and development of sustainable clay-based building materials with natural additives and local agricultural waste
No full textAn experimental research is ongoing in the “Laboratorio di Termofisica dei Materiali” of Politecnico di Bari on sustainable building materials achieved by a basic mix of clay, silt, sand with local additives (i.e. lime) and natural components originating from agricultural waste produced in Mediterranean area (i.e. straw, olive trees waste, etc.). The agro-waste disposal represents one of the main issue at national and international level.
The research aims to develop a sustainable material suitable for building applications (i.e panels, bricks, mortar) with high physical and hygrothermal performances
Requisiti termici dinamici dell'involucro opaco alla luce dell'attuale quadro normativo
No full textNell'articolo si dimostra che l’involucro opaco svolge un ruolo importante nella determinazione della prestazione termoenergetica complessiva dell’edificio, ma resta comunque solo uno dei fattori influenti. Soprattutto in regime termico dinamico l’interazione tra le varie componenti di involucro, il clima esterno, gli apporti interni e l’impianto, può essere tale da rendere imprevedibile la prestazione reale in opera. *** The paper demonstrates that the opaque envelope plays an important role in determining the overall energy performance of the building, but it is still only one of the factors influential. In dynamic thermal regime the interaction between the various envelope’s components, the external climate, the internal gains and the HVAC system, may be such as to make unpredictable performance in real operation
Fundamental parameters of heat and moisture transfer for energy efficiency in buildings
No full textHeat and moisture transfer in a room is critical for the indoor comfort. This first chapter introduces the basic concepts of heat and moisture transfer in buildings, dealing with the main theoretic fundamentals. It focuses on the most common parameters, used to analyze heat and moisture transfer in buildings. Furthermore this section takes into account a numerical model to calculate the simultaneous heat and moisture transfer in building materials. It is demonstrated that both the microstructure and physical parameters, e.g. density and porosity, may influence greatly the hygrothermal behaviour of the building materials. This is the reason why this chapter also gives prominence to the porous materials
Soil based Building Materials for Energy Efficiency
No full textA descriptive analysis and some definitions of clays are provided at the beginning of the
chapter; after that the most common earthen materials are introduced. A list of the most common
worldwide building techniques and physical parameters is provided. The main building regulations
are reported in a brief summary.
At the end of the chapter, according to the main important studies, hygrothermal and physical
performances of earthen building materials are discusse
La verifica termoigrometrica dell’involucro opaco secondo il D.M. 26 giugno 2015 "requisiti minimi"
No full textLa verifica termoigrometrica dell’involucro opaco, con l’entrata in vigore del Decreto Requisiti
Minimi nel 2015, è divenuta un vincolo progettuale non semplice da superare. La richiesta
assenza di rischio muffa sulla superficie interna dell’involucro e l’assoluta assenza di condensa
interstiziale ha complicato il progetto dell’involucro opaco dal punto di vista termoigrometrico.
Questo articolo illustra le modalità di calcolo con esempi e casi pratici
Analisi numerica e sperimentale della trasmissione del calore nelle cavità d’aria dei blocchi forati
No full textThe thermal performance of hollow bricks, as elements of the building envelope, is mainly linked to the presence of air cavities. The heat propagates within those components through the three basic modes of transmission: conduction in the solid matrix, convection of the air cavity, direct radiation between surfaces that face in the cavities.
The rigorous treatment of such heat exchange is very complex even in thermal conditions close to the environment with moderate temperature differences. In engineering practice a simplified calculation method is used, as incorporated in national and international standards, which reduce heat transfer into the cavity to an equivalent heat conduction that results in the transport of the same thermal power.
UNI EN ISO 6946 and UNI 10355 follow this method by proposing a simplified model of computation that lead to different results.
Given the importance that the correct assessment of the insulation performance of the envelop in the context of energy certification of buildings it was considered useful to undertake a detailed analysis of the reliability of the estimation methods of heat transfer in air cavities of hollow bricks.
The study was conducted with the use of different tools, numerical and experimental. An experimental study was conducted in the laboratory with heat transmission measurements, in specimens with parallelepiped cavities, through the guarded hot plate apparatus according to UNI EN 12664.
The analysis of the results, numerical and experimental, compared with the predictions obtained from simplified models of technical standards, have called attention to the order of magnitude of the calculation accuracy obtainable with such procedures. For certain geometric configurations and boundary conditions, the application of the standard procedures can lead to large errors of evaluation of the thermal resistance of the cavity
Building with earth, a sustainable material for efficient buildings
No full textThe hygrothermal behaviour of a small building in a Mediterranean climate was studied by comparing
three different solutions for the walls: concrete, fired clay and unbaked earthen walls. Several
numerical simulations, with EnergyPlus, were carried out on the IEA BESTEST building. The
evolution of the indoor relative humidity has proved that the unbaked earth significantly dump the
fluctuations in indoor air relative humidity. This effect was generated by the better moisture buffering
capacity of the unbaked earthen wall and by its lower water vapour resistance coefficient. The aim of
the ongoing experimental research is to obtain a low cost-high performance building material suitable
to achieve better indoor hygrothermal comfort in modern sustainable and efficient buildings
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