Implementation of moist air in large air volumes simulations for energy-related efficiency in buildings

LAUREA MAGISTRALENegli ultimi anni è stato in gran parte dimostrato che il consumo globale energetico è largamente dovuto all’utilizzo di energia degli edifici e degli agglomerati urbani. E’ stato osservato più precisamente che il dispendio energetico maggiore è causato dagli impianti di condizionamento e riscaldamento degli edifici (HVAC). I due principali modi per ridurre al minimo i suddetti consumi sono l’utilizzo di tecniche di costruzione sempre più all’avanguardia, impiegando materiali sempre più efficienti dal punto di vista energetico, e l’adozione di sistemi di controllo innovativi per la gestione energetica. In questo lavoro mi sono occupato di esporre una completa revisione dei principali software e paradigmi modellistici che siano in grado di supportare il difficile problema della progettazione di edifici (o raggruppamenti di essi) ad alta efficienza energetica. La progettazione di questi ultimi è ampiamente limitata dalla complessità degli stessi, intesi come sistemi, le cui performance sono determinate dall’interazione dei vari sottosistemi di cui sono composti. Negli ultimi 50 anni sono stati prodotti innumerevoli software in aiuto della simulazione delle performace energetiche degli edifici. Negli ultimi anni in particolare sono state implementate tecniche molto utili in questo ambito, note come Object-Oriented Modeling and Simulation (OOMS), sono basate sul concetto di equazioni anzichè di algoritmi. Tale approccio risulta agevole e riesce a risolvere molte difficoltà di modellazione. In questa tesi, tramite l’approccio modellistico Object Oriented del linguaggio Modelica si è attuato un processo di ’restauro’ e di ampliamento di una precedente libreria atta alla modellazione di ampi volumi d’aria all’interno di edifici. L’obiettivo è quello di ricreare una situazione di modello il più vicina possibile alla realtà al fine di arrivare a simulazioni sempre più veritiere e introdurre maggiori gradi di complessità. Successivamente le idee presentate sono state supportate da alcune applicazioni e simulazioni che mettono in pratica le tecniche proposte.In recent years it has been largely demonstrated that global energy consumption is largely due to the energy use of buildings and urban agglomerations. More precisely, it has been observed that the greatest energy expenditure is caused by the Heating, Ventilation and Air Conditioning of buildings (HVAC). The two main ways to minimize the mentioned consumption are the use of advanced construction techniques, using increasingly energy-efficient materials, and the adoption of innovative control systems for energy management. In this work one has dealt with a complete review of the main software and modeling paradigms that are able to support the difficult problem of designing buildings (or groups of them) with high energy efficiency. The design of the latter is largely limited by the complexity of the same, viewed as systems, whose performances are determined by the interaction of the various subsystems of which they are composed. In the last 50 years, countless software programs have been produced to help simulate the energy performance of buildings. In the last few years in particular, very useful techniques have been implemented in this area, known as Object-Oriented Modeling and Simulation (OOMS), based on the concept of equations rather than algorithms. This approach is easy and manages to solve many modeling difficulties. In this thesis, through the Object Oriented modeling approach of the Modelica language, a process of ’restoration’ and expansion of a previous library for the modeling of large volumes of air inside buildings is carried out. The goal is to recreate a model situation as close as possible to reality in order to reach increasingly truthful simulations and introduce greater degrees of complexity. Subsequently the ideas presented were supported by some applications and simulations that put the proposed techniques into practice

Predicting the Performance of a Solar Domestic Water Heating System with Evacuated Tube Collectors and Hydronic Radiant Flooring

Residential solar thermal system installations have been significantly increasing in the last decade and there exists limited resources for reasonably predicting the performance of those systems. A simulated model is developed in MATLAB® and used to predict the performance of a solar domestic water heating system. In the simulated system, hot water is generated using evacuated tube solar collectors and stored in a domestic hot water storage tank, which utilizes immersed coil heat exchangers. The system is designed to provide hydronic radiant floor heating to its occupants based on the heat loss of a building energy model for an energy-efficient home. Performance characteristics of the components from well-known manufacturers are utilized where available. Some of the parameters are easily changeable so that several manufacturers\u27 characteristics could be compared using the model. The system\u27s sensitivity to tank thermal stratification and tank size are investigated. For solar intermittencies, the energy required for auxiliary domestic water heating is determined by the model as well. Some empirical investigations of two sets of evacuated tube collectors were used to compare the validity of the model. Results are presented in terms of temperatures and heat gains

Origins of Analysis Methods in Energy Simulation Programs Used for High Performance Commercial Buildings

Current designs of high performance buildings utilize hourly building energy simulations of complex, interacting systems. Such simulations need to quantify the benefits of numerous features including: thermal mass, HVAC systems and, in some cases, special features such as active and passive solar systems, photovoltaic systems, and lighting and daylighting systems. Unfortunately, many high performance buildings today do not perform the way they were simulated. One potential reason for this discrepancy is that designers using the simulation programs do not understand the analysis methods that the programs are based on and therefore they may have unreasonable expectations about the system performance or use. The purpose of this study is to trace the origins of a variety of simulation programs and the analysis methods used in the programs to analyze high performance buildings in the United States. Such an analysis is important to better understand the capabilities of the simulation programs so they can be used more accurately to simulate the performance of an intended design. The goal of this study is to help explain the origins of the analysis methods used in whole-building energy simulation, solar system analysis simulation or design, and lighting and daylighting analysis simulation programs. A comprehensive history diagram or genealogy chart, which resolves discrepancies between the diagrams of previous studies, has been provided to support the explanations for the above mentioned simulation programs

Photovoltaic system with multilevel converter coupled to a compressed air energy storage system for grid integration.

M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.Electricity demand is continuously increasing and nations including South Africa, are looking to exploit renewable energy sources to augment conventional electricity generation. An analysis of electricity demand and supply, the electricity infrastructure and the status of renewable electricity including the progress and plans made thereof in South Africa were carried out. A review of the challenges affecting the bulk exploitation of renewable energy (RE) resources and its future prospects are discussed to determine the sustainability of these efforts. This research investigation focuses on a simulation model designed to harness the energy from the sun through a photovoltaic system. Based on empirical data of environmental conditions, a photovoltaic (PV) system model to generate 30 MW of electricity at Witkop substation, Polokwane (South Africa) was developed and to be fed into the grid. A maximum power point tracker (MPPT) control scheme is utilised to ensure that maximum power can be derived from the PV plant. A modular multi-level converter (MMLC) is utilised to convert the electricity generated by the PV system from direct current (DC) to alternative current (AC). The MMLC coupled to compressed air energy storage (CAES) stores the electricity generated during the day and injects it into the grid during peak periods of electricity demand. Mathematical models of the PV system, the MMLC, the CAES and the grid integration were developed, modelled and simulated to describe the electrical behaviour and to establish the ideal operational parameters of the various systems components. Furthermore, validation of the performance of the system components in the simulation model were carried out against manufacturers’ data sheets for similar studies and prototypes. The simulation model were used to combine all the system components effectively into the grid based on the electricity generation system configurations, electricity demand and the environmental conditions of the selected site. More importantly, this investigation seeks to increase the effort of development of PV generation models in the field of renewables when compared to other alternative energy sources such as wind energy generation

Efficient modelling and simulation techniques for energy related system level studies in buildings

Ad oggi, è stato ampiamente riconosciuto che il consumo energetico su scala globale dipende in larga parte dal consumo degli edifici. E' stato anche osservato che il loro consumo possa essere notevolmente ridotto agendo in due direzioni principali: l'utilizzo di materiali più efficienti dal punto di vista energetico, migliorare le tecniche di costruzione, i dispositivi per la climatizzazione, eccetera; mentre la seconda, prevede l'adozione di politiche per il controllo e gestione dell'energia. All'interno dello scenario esposto, la tesi si occupa dello sviluppo di modelli e di paradigmi modellistici che siano in grado di supportare il difficile problema della progettazione di edifici (o raggruppamenti di essi) al alta efficienza energetica; senza precludere la ristrutturazione ed il miglioramento dell'esistente. Una caratteristica distintiva del lavoro è che nonostante si parli di edifici, in realtà l'analisi si rivolge anche agli impianti contenuti al loro interno. Questo aspetto rende i risultati ottenuti applicabili anche ad altri contesti. E' importante sottolineare che uno dei limiti principali nella progettazione (o eventuali riprogettazioni) degli edifici ad elevata efficienza energetica, è la complessità dell'edificio inteso come sistema, le cui performance sono determinate dalle interazioni dei svariati sottosistemi che lo compongono. Pertanto, la progettazione di un sistema così complesso ed eterogeneo, per essere efficace deve essere supportata da strumenti informatici. Per questo motivo, negli ultimi 50 anni sono stati sviluppati molti software per la simulazione delle performance energetiche degli edifici, e molti di questi sono ancora in uso all'interno della comunità dei progettisti. Tuttavia, molti esperti si chiedono se questi strumenti saranno in grado di affrontare le nuove sfide in modo efficace. Negli ultimi anni, nuove tecniche per la modellistica e simulazione hanno preso piede in molti ambiti sia nel campo scientifico che industriale. L'obiettivo della tesi è di sfruttare i principi delle tecniche sopracitate in modo da fornire dei modelli -- e più in astratto metodologie modellistiche -- che siano in grado di risolvere i principali problemi dei software per la simulazione dei consumi energetici degli edifici. Pertanto, i contributi di questo lavoro sono riassunti in seguito. (i) Mostrare come integrare in un unico framework problemi che altrimenti richiederebbero l'ausilio di diversi strumenti di simulazione, a svantaggio della simulazione d'insieme dell'edificio. Le idee proposte sono esemplificate mostrando come integrare uno dei punti più critici, la simulazione dell'aria all'interno di grandi spazi. (ii) Le stesse idee, sebbene applicate in un contesto completamente diverso, si dimostrano in grado di rappresentare in modo realistico i sistemi di controllo. Infatti, le performance energetiche potrebbero essere migliorate significativamente se i sistemi di controllo fossero accuratamente ottimizzati. Tuttavia, l'ottimizzazione risulta impossibile solo se l'edificio ed il sistema di controllo possono essere simulati contemporaneamente. (iii) I principi della modellistica Object-Oriented sono stati sfruttati per la realizzazione di modelli aventi diversi livelli di dettaglio. Tali modelli permettono l'adattamento del modello di simulazione a una qualsiasi delle fasi di progetto, concentrandosi sulla parte in questione e semplificando le altre. E' evidente che la possibilità di adattare il livello di dettaglio dei modelli porti grandi benefici al flusso di progettazione, presentandosi come uno strumento in grado di seguirne il ciclo completo. (iv) Le idee presentate nella tesi sono state supportate da molte applicazioni e simulazioni che esemplificano l'utilizzo delle tecniche proposte, evidenziandone l'applicabilità ed il potenziale.It is universally acknowledged that buildings contribute to a very significant extent to the world energy demand. It is also recognised that said contribution can be dramatically reduced by acting along two main directions: to employ better materials, construction techniques, climatisation devices, lighting, appliances, while the second is to adopt improved control and energy management policies. In such a scenario, this dissertation deals with the definition and realisation of a modelling and simulation paradigm suitable for supporting all the steps of so complex a problem as the design of a new energy efficient building or neighbourhood, and also the refurbishment of an existing one in a view to reducing its energy footprint. As an important peculiarity of the work, it is to be noticed that despite the presented research is said to refer to ``buildings'' for brevity, in fact the installed plants are considered as well. This makes the obtained results applicable also in other domains. In this respect, it is worth noticing right from the beginning that one of the most significant barriers to energy efficient building (re)design is that buildings are complex systems, the energy performance of which is affected by the interaction of several parts and phenomena. The design of such complex and heterogeneous systems apparently needs to be supported by computer aided tools. In fact, during the past 50 years, a wide variety of building energy simulation programs have been developed, and some are nowadays commonly in use throughout the building energy community. However, many experts wonder if these tools will be able to address the future needs in an effective way. In recent years, new modelling and simulation techniques have gained interest in the scientific and professional communities of a variety of fields. The aim of this work is to exploit these techniques so as to provide models, and modelling methodologies, to overcome the main shortcomings of the Energy and Building Performance Simulation tools presently available. As such, the contribution of this dissertation can be summarised as follows. (i) It is shown how to use OOMS to represent in a unitary framework phenomena that would otherwise call for different simulation and analysis tools, to the detriment of a coordinated and whole-system, approach. The proposed general ideas are exemplified by addressing and solving (among others) maybe the toughest problem of this type, i.e., the modelling and simulation of large air volumes. (ii) The same ideas, though differently declined, are shown to be capable of accommodating for a reliable representation of control systems. In fact, if properly optimised can provide significant energy performance improvements, but such an optimisation is hardly possible if the building and its controls cannot be represented and simulated jointly. (iii) The principles of OOMS are exploited so as to allow for models of scalable detail level, which permits to tailor the simulation model complexity to any particular study at hand, concentrating on the relevant parts of the system and employing simple - thus computationally fast - descriptions of the rest. It is worth noticing that the possibility of scaling the detail level is highly beneficial also in a view to have the simulation tool follow the entire life cycle of a project. (iv) Several simulation studies are proposed and discussed, to better explain the presented ideas and to show their actualDIPARTIMENTO DI ELETTRONICA, INFORMAZIONE E BIOINGEGNERIA25SCATTOLINI, RICCARDOFIORINI, CARLO ETTOR

Proceedings of the COST Action TU1403 : Adaptive Facades Network Final Conference

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Proceedings of 8th International Conference Improving Energy Efficiency in Commercial Buildings (IEECB’14)

This book contains the proceedings of the 8th International Conference on Energy Efficiency in Commercial Buildings which took place in Frankfurt, Germany 1-3 April 2014. The IEECB conference brings together all the key players from this sector, including commercial buildings’ investors and property managers, energy efficiency experts and building technologies researchers, equipment manufacturers, service providers (ESCOs, utilities, facilities management companies) and policy makers, with a view to exchange information, to learn from each other and to network. The wide scope of topics covered during the IEECB’14 conference includes: smart building and low energy buildings, (Nearly) Net Zero Energy Buildings, equipment and systems (lighting, HVAC auxiliary equipment, ICT & office equipment, miscellaneous equipment, BEMS, electricity on-site production, renewable energies, etc.) and the latest advances in energy efficiency programmes, regulation & policies for public and private sector commercial buildings. Potential readers who may benefit from this book include researchers, engineers, policymakers, energy agencies, electric utilities, and all those who can influence the design, selection, application, and operation of electrical motor driven systems.JRC.F.7-Renewables and Energy Efficienc