1,721,383 research outputs found
Energy reduction measures in agricultural greenhouses heating: Envelope, systems and solar energy collection
No full textWhile a great reduction of the energy demand for the environmental control of civil buildings has been reached in recent years, still a great potential of energy savings lies in other sectors like the one of agricultural production. The scope of this paper is to investigate the energy performance of some of the recent envelope and systems technologies that best can contribute to a great reduction of the energy demand for the climatic control of a greenhouse for intensive crop production. This article concentrates on three aspects: the use of polycarbonate hollow sheets to reduce the thermal transmittance of the glazing, the application of polypropylene sheets as a basal heating system and the solar energy capture by means of low cost plastic solar collectors. A tunnel greenhouse for basil production of 40 m of length and 10 m of width was considered as a case study and modelled within the EnergyPlus simulation software. The climate locations that were considered refer to the north-west of Italy. The results show that savings of the order of 30% can be achieved by using more insulated transparent materials. On the contrary, the application of the solar collectors still remains problematic because of the large land use and lower global efficiencie
Feasibility of polygeneration in energy supply systems for health-care facilities under the Italian climate and boundary conditions
No full textThis article investigates the opportunities of a multi-energy system in a hospital facility under the Italian climate and boundary conditions. One of the benchmarks for tertiary buildings constructed by the U.S. DOE (Department of Energy) to be used in association with the energy simulation software EnergyPlus was taken as a reference hospital. After importing that benchmark under the Italian climatic conditions (in the Turin, Florence and Naples locations) and determining the energy needs for heating energy, cooling energy and electricity, several polygeneration alternatives were presented. The reference configuration of the benchmark case study is based on a one-energy rationale (one energy carrier for each load), while the polygeneration alternatives (cogeneration, trigeneration and renewable) are based on a multi-energy rationale (variable energy carriers used in several converters to cover the same load with the maximum efficiency and reliability). By means of a multi-energy systems modeling framework, the scenarios that are most efficient or profitable were determined. Results show that renewable energy is far from covering the whole energy demand of a hospital, and that - given the actual Italian primary energy weighting factor for electricity, that is the amount of source energy required for the production of one unit of electricity in Italy - trigeneration can be feasible only from an economic point of view, and not from an energy point of view. © 2011 International Energy Initiativ
Zero Energy Buildings: A Reached Target or a Starting Point?
Full text linkThe debate about zero energy buildings (ZEBs) has been one of the main new drivers of innovation in the construction industry around the world in the past decade. What may have been seen ten years ago as a theoretical objective has become a current construction standard. Most of the new buildings in various countries, at least the European ones, are now highly-performing buildings (in Europe they are called nearly zero energy buildings), and achieving the high-performance targets became compulsory
Il significato del fattore di utilizzazione nel calcolo semplificato del fabbisogno termico degli edifici: aspetti teorici e applicativi
No full textCriticità nell'impiego di sistemi di gestione dell'energia e del comfort negli edifici
No full textCon la concezione dell’edificio a energia quasi zero, in cui un fabbisogno energetico molto basso o quasi nullo è coperto in misura molto significativa da energia da fonti rinnovabili e la cui prestazione energetica è condizionata dalle tecnologie edilizie e impiantistiche oggi disponibili e dai loro costi di mercato, il progettista non ha più possibilità né ragioni per migliorare le prestazioni energetiche dell’edificio oltre i valori imposti dalla normativa. L’attenzione si sposta dunque dalla progettazione all’esercizio, con la duplice finalità di contenere lo scostamento delle prestazioni energetiche dell’edificio rispetto a quelle ottimali previste in sede di progettazione e di contenere i costi di esercizio
attesi. Nella sua azione l’occupante di una unità abitativa o il facility manager di una realtà terziaria o industriale, trova, in teoria, un efficace supporto nei sistemi di automazione, controllo e supervisione degli impianti tecnologici (e l’azione della Commissione Europea è chiaramente indirizzata a favorirne l’impiego attraverso l’introduzione di una certificazione di “smartness” degli edifici), ma nella realtà si riscontrano non poche criticità a causa della carenza di mezzi di informazione/istruzione dei soggetti interessati
Assessment of building cooling energy need through a quasi-steady state method: simplified correlation for gain – loss mismatch
No full textThe objective of this work is to implement a simplified calculation procedure for building net energy need, based on a quasi-steady state model and on a monthly data set. In particular, it is intended to supply a formulation of the dynamic parameters and to adapt them to Italian climatic, typological, constructive and user data. The method was validated by determining the numerical correlations of the gain/loss utilization factor, through a comparison with a detailed building energy simulation software (EnergyPlus). The simulation was run on some test rooms defined by CEN (European Committee for Standardization) and on some real buildings that are representative of the Italian building stock, assuming weather data from different Italian locations (Torino, Roma, Palermo). The work shows that the accuracy of results is greatly affected by nonlinearities in the determination of the heat transfer and that the dynamic parameters are sensitive to some building features which are not taken into account in the CEN correlations
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