Almacenamiento de energ��a t��rmica por calor latente en los edificios: bases para la optimizaci��n de aplicaciones pasivas, opacas y trasl��cidas

La principal motivaci��n para la elecci��n del tema de la tesis es nuestra realidad energ��tica y ambiental. Y m��s espec��ficamente, la necesidad urgente de dar una respuesta a esta realidad desde el sector de la edificaci��n. Por lo que, el trabajo parte de la b��squeda de soluciones pasivas que ayuden a la reducci��n del consumo energ��tico y de las emisiones de C02 de los edificios, tanto nuevos como existentes. El objeto de estudio son aplicaciones innovadoras, basadas en el uso de materiales reactivos, con un efecto t��rmico de memoria bidireccional. La energ��a es un elemento imprescindible para el desarrollo. Sin embargo, el modelo energ��tico predominante, basado principalmente en la utilizaci��n de combustibles de origen f��sil, es uno de los importantes responsables del deterioro ambiental que sufre el planeta. Adem��s, sus reservas son limitadas y est��n concentradas en unas pocas regiones del mundo, lo que genera problemas de dependencia, competitividad y de seguridad de suministro. Dado el gran potencial de ahorro energ��tico del sector de la edificaci��n, la Uni��n Europea en sus directivas enfatiza la necesidad de mejorar la eficiencia energ��tica de los edificios. A��adiendo, adem��s, la obligatoriedad de desarrollar edificios ���energ��a casi nula���, cuyo prerrequisito es tener un muy alto rendimiento energ��tico. En Espa��a, los edificios son responsables del 31% del consumo de energ��a primaria. La mayor parte de este consumo se relaciona a la utilizaci��n de sistemas activos de acondicionamiento. Una medida efectiva para reducir la demanda es mejorar la envolvente. Sin embargo, hay que buscar estrategias adicionales para aumentar a��n m��s la eficiencia de los edificios nuevos y existentes. Para los climas de Espa��a, el uso de la inercia t��rmica ha probado ser una estrategia v��lida. Sin embargo, su funcionamiento est�� vinculado al peso y al volumen de los materiales utilizados. Esto limita sus posibilidades en la rehabilitaci��n energ��tica y en los nuevos edificios basados en la construcci��n ligera. Una alternativa es el uso de aplicaciones de almacenamiento t��rmico por calor latente, utilizando materiales de cambio de fase (PCM). Los PCM son sustancias con un muy alto calor de fusi��n, capaces de almacenar una gran cantidad de energ��a t��rmica sin requerir aumentos significativos de peso o volumen. Estas caracter��sticas los hacen id��neos para reducir el consumo relacionado con el acondicionamiento t��rmico, en edificios nuevos y existentes. En la parte preliminar de la investigaci��n, se encontr�� que para lograr un aprovechamiento ��ptimo de las aplicaciones con PCM es necesario tener un conocimiento profundo de su funcionamiento y de las variables del sistema. De ah�� que el objetivo principal de la presente tesis sea: establecer las bases para la optimizati��n integral de las aplicaciones con almacenamiento de energ��a t��rmica por calor latente, identificando y validando sus variables m��s relevantes. La investigaci��n consta de tres partes. La primera, documental, sistematizando y jerarquizando la informaci��n cient��fica publicada; la segunda, num��rica, basada en un an��lisis param��trico de una aplicaci��n con PCM, utilizando simulaciones t��rmicas; y la tercera, experimental, monitorizando el funcionamiento t��rmico y energ��tico de diferentes aplicaciones con PCM en m��dulos a escala real. Los resultados brindan un m��s profundo entendimiento del funcionamiento de las aplicaciones evaluadas. Han permitido identificar sus variables relevantes, cuantificar su influencia, y determinar condiciones ��ptimas para su utilizaci��n as�� como situaciones en las que ser��a muy dif��cil justificar su uso. En el proceso, se realiz�� la caracterizaci��n t��rmica y energ��tica de aplicaciones con PCM, tanto opacas como trasl��cidas. Adem��s, se ha encontrado que las aplicaciones con PCM son capaces de aumentar la eficiencia energ��tica inclusive en recintos con dise��os optimizados, demostrando ser una de las estrategias adecuadas para lograr el muy alto desempe��o energ��tico requerido en los edificios energ��a nula. ABSTRACT The main motivation for choosing the theme of the thesis is our energy and environmental reality. And more specifically, the urgent need to respond to this reality from the building sector. This is why, the work start with the search of passive solutions that help reduce energy consumption and C02 emissions of buildings, in both new and existing ones. The object of study is innovative applications based on the use of responsive materials, with bidirectional thermal memory. Energy is an essential element for development. However, the predominant energy model, based primarily on the use of fossil fuels, is one of the major responsible for the environmental deterioration of the planet, the cause of most of the CO2 emissions. Furthermore, reserves of fossil fuels are limited and are concentrated in a few regions of the world, which creates issues related to dependency, competitiveness, and security of supply. Given the large potential for energy savings in the building sector, the European Union in its directives emphasizes the need to improve energy efficiency in buildings. Also, adding the obligation to develop "nearly zero energy" buildings, whose first prerequisite is to achieve a very high energy efficiency. In Spain, buildings are responsible for 31% of primary energy consumption and most of this consumption is related to the used of HVAC systems. One of the most effective measures to reduce demand is to improve the envelope. However, it is necessary to look for additional strategies to further increase the efficiency of new and existing buildings. For the predominant climates in Spain, use of the thermal inertia may be a valid strategy. Nevertheless, its operation is linked to weight and volume of the materials used. This limits their possibilities in the existing buildings energy retrofitting and in the new buildings based on lightweight construction. An alternative is the use of latent heat thermal energy storage applications (LHTES), using phase change materials (PCM). PCM are substances with a high heat of fusion, capable of storing a large amount of thermal energy without requiring significant increases in weight or volume. These features make them ideal for reducing energy consumption associated with thermal conditioning in both new and existing buildings. In the preliminary part of the investigation, it was found that to get optimum utilization of the PCM applications is needed to have a deep understanding of its operation and, in particular, how the system variables affect its performance. Hence, the main objective of this thesis is: to establish the basis for the integral optimization of applications with latent heat thermal energy storage, identifying and validating the most relevant variables. The research comprises of three parts. The first, documentary, systematizing and prioritizing published scientific information. The second, numeric, based on a parametric analysis of an application PCM using thermal simulations. The third, experimental, monitoring the thermal and energy performance of different applications with PCM on real scale test cells. The results provide a complete understanding of the functioning of the evaluated LHTES application. They have allowed to identify their relevant variables, quantify their influence and determine optimum conditions for use as well as situations where it would be very difficult to justify its use. In the process, it was carried out the power and thermal characterization of various opaque and translucent PCM applications. Furthermore, it has been found that applications with PCM can increase the energy efficiency, even in buildings with optimized designs; proving to be one of the appropriate measures to achieve the high energy performance required in zero energy buildings.

Application of the nZEB methodology in the retrofitting of a typical Portuguese dwelling from the 60's.

Buildings and the whole built environment are in a key role when societies are mitigating climate change and adapting to its consequences. More than 50% of the existing residential buildings in EU-25 were built before 1970. Thus, these buildings are of significant importance in reducing energy consumption and CO2 emissions. The existence of more nearly zero energy buildings (nZEB) is a possible solution for this problem. This study aims to analyze the application of the nZEB methodology in the retrofitting of a typical Portuguese dwelling build in 1950. It was shown that the primary energy used can be reduced to a very low value (11,95 kWhep/m2.y) in comparison with the reference consumption (69,15 kWhep/m2.y), with the application of the best construction techniques together with the use of energy from on-site renewable sources.

An investigation of the required skills for the delivery of low and zero carbon buildings within a region

The United Kingdom is committed to a raft of requirements to create a low-carbon economy. Buildings consume approximately 40% of UK energy demand. Any improvement on the energy performance of buildings therefore can significantly contribute to the delivery of a low-carbon economy. The challenge for the construction sector and its clients is how to meet the policy requirements to deliver low and zero carbon (LZC) buildings, which spans broader than the individual building level, to requirements at the local and regional levels, and wider sustainability pressures. Further, the construction sector is reporting skills shortages coupled with the need for ���new skills��� for the delivery of LZC buildings. The aim of this paper is to identify, and better understand, the skills required by the construction sector and its clients for the delivery of LZC buildings within a region. The theoretical framing for this research is regional innovation system (RIS) using a socio-technical network analysis (STNA) methodology. A case study of a local authority region is presented. Data is drawn from a review of relevant local authority documentation, observations and semi-structured interviews from one (project 1) of five school retrofit projects within the region. The initial findings highlight the complexity surrounding the form and operation of the LZC network for project 1. The skills required by the construction sector and its clients are connected to different actor roles surrounding the delivery of the project. The key actors involved and their required skills are: project management and energy management skills required by local authority; project management skills (in particular project planning), communication and research skills required by school end-users; and a ���technical skill��� relating to knowledge of a particular energy efficient measure (EEM) and use of equipment to implement the EEM is required by the EEM contractors.

Energy efficiency evaluation of zero energy houses

Given the global energy and environmental situation, the European Union has been issuing directives with increasingly demanding requirements in term of the energy efficiency in buildings. The international competition of sustainable houses, Solar Decathlon Europe (SDE), is aligned with these European objectives. SDE houses are low energy solar buildings that must reach the near to zero energy houses��� goal. In the 2012 edition, in order to emphasize its significance, the Energy Efficiency Contest was added. SDE houses��� interior comfort, functioning and energy performance is monitored. The monitoring data can give an idea about the efficiency of the houses. However, a jury comprised by international experts is responsible for carrying out the houses energy efficiency evaluation. Passive strategies and houses services are analyzed. Additionally, the jury's assessment has been compared with the behavior of the houses during the monitoring period. Comparative studies make emphasis on the energy aspects, houses functioning and their interior comfort. Conclusions include thoughts related with the evaluation process, the results of the comparative studies and suggestions for the next competitions.

Study of low grade temperature CCHP systems for the realization of zero power buildings

Combined Cooling Heat and Power Generation (CCHP) or trigeneration has been considered worldwide as a suitable alternative to traditional energy systems in terms of significant energy saving and environmental conservation. The development and evaluation of a solar driven micro-CCHP system based on a ORC cogenerator and an Adsorption Chiller (AC) experimental prototypes has been the focus of this PhD research. The specific objectives of the overall project are: ��� To design, construct and evaluate an innovative Adsorption Chiller in order to improve the performances of the AC technology. ��� To thermodynamically model the proposed micro-scale solar driven CHP system and to prove that the concept of trigeneration through solar energy combined with an organic Rankine turbine cycle (ORC) and an adsorption chiller (AC) is suitable for residential applications.

Splitting of the zero-energy edge states in bilayer graphene

Bilayer graphene nanoribbons with zigzag termination are studied within the tight-binding model. We also include single-site electron-electron interactions via the Hubbard model within the unrestricted Hartree-Fock approach. We show that either the interactions between the outermost edge atoms or the presence of a magnetic order can cause a splitting of the zero-energy edge states. Two kinds of edge alignments are considered. For one kind of edge alignment (?) the system is nonmagnetic unless the Hubbard parameter U becomes greater than a critical value Uc. For the other kind of edge alignment (?) the system is magnetic for any U>0. Our results agree very well with ab initio density functional theory calculations.

Converg��ncia para NZEB de um edif��cio classificado

Disserta����o para obten����o do grau de Mestre em Engenharia Civil na ��rea de Edifica����es

NZEB: um desafio para a engenharia civil

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia Civil

Estudo experimental de um sistema BIPV/T-PCM

A Uni��o Europeia tem dado cada vez mais enfoque �� efici��ncia energ��tica nos edif��cios e �� sua capacidade de produ����o de energia, tendo lan��ado a directiva ���Energy Performance of Buildings Directive��� com o intuito de que at�� 31 de Dezembro de 2018 todos os edif��cios novos sejam ���nZEB-nearly Zero Energy Building���, o que significa que devem por um lado diminuir o seu consumo energ��tico, aumentando a sua efici��ncia, e por outro lado produzir localmente e atrav��s de fontes de energias renov��veis toda, ou quase toda, a energia de que necessitam. A presente tese est�� integrada no Projecto ���Frame ��� Prefabricated systems (modules) for low-energy buildings: design, prototyping and testing��� (Ref: PTDC/AURAQI-AQI/117782/2010) que est�� a ser desenvolvido na Unidade de Efici��ncia Energ��tica do Laborat��rio Nacional de Energia e Geologia (LNEG). Neste trabalho �� desenvolvido e analisado um sistema BIPV/T-PCM (Building Integrated Photovoltaic Thermal ��� Phase Change Materials) que engloba todo um novo conceito de capta����o, armazenamento e gest��o da energia solar em fachadas. Este sistema �� composto por um m��dulo fotovoltaico, uma bateria de PCM (Materiais de Mudan��a de Fase) e todo um sistema de fluxo de ar que permite a gest��o da energia colectada e armazenada. Foi tamb��m desenvolvido teoricamente um c��digo de gest��o energ��tica para a manipula����o do sistema. O sistema em estudo apoia-se em tr��s objectivos principais: aquecer no inverno; arrefecer no ver��o; e aumentar a efici��ncia do PV arrefecendo-o. Na sequ��ncia do trabalho realizado verificou-se que o conceito do sistema em estudo alcan��a alguns dos objectivos propostos, tendo ainda potencial para se continuar o seu desenvolvimento. O sistema em estudo �� um sistema inovador, e como tal est�� a ser registada uma patente com base no conceito desenvolvido.

Asymptotically Zero Energy Computing Using Split-Level Charge Recovery Logic

The dynamic power requirement of CMOS circuits is rapidly becoming a major concern in the design of personal information systems and large computers. In this work we present a number of new CMOS logic families, Charge Recovery Logic (CRL) as well as the much improved Split-Level Charge Recovery Logic (SCRL), within which the transfer of charge between the nodes occurs quasistatically. Operating quasistatically, these logic families have an energy dissipation that drops linearly with operating frequency, i.e., their power consumption drops quadratically with operating frequency as opposed to the linear drop of conventional CMOS. The circuit techniques in these new families rely on constructing an explicitly reversible pipelined logic gate, where the information necessary to recover the energy used to compute a value is provided by computing its logical inverse. Information necessary to uncompute the inverse is available from the subsequent inverse logic stage. We demonstrate the low energy operation of SCRL by presenting the results from the testing of the first fully quasistatic 8 x 8 multiplier chip (SCRL-1) employing SCRL circuit techniques.

Supersymmetric Isospectral Formalism for the Calculation of Near-Zero Energy States: Application to the Very Weakly Bound He-4 Trimer Excited State

We propose a novel mathematical approach for the calculation of near-zero energy states by solving potentials which are isospectral with the original one. For any potential, families of strictly isospectral potentials (with very different shape) having desirable and adjustable features are generated by supersymmetric isospectral formalism. The near-zero energy Efimov state in the original potential is effectively trapped in the deep well of the isospectral family and facilitates more accurate calculation of the Efimov state. Application to the first excited state in He-4 trimer is presented.

Passive design strategies and performance of Net Energy Plus Houses

The first step in order to comply with the European Union goals of Near to Zero Energy Buildings is to reduce the energy consumption in buildings. Most of the building consumption is related to the use of active systems to maintain the interior comfort. Passive design strategies contribute to improve the interior comfort conditions, increasing the energy efficiency in buildings and reducing their energy consumption. In this work, an analysis of the passive strategies used in Net Energy Plus Houses has been made. The participating houses of the Solar Decathlon Europe 2012 competition were used as case studies. The passive design strategies of these houses were compared with the annual simulations, and the competition monitored data, especially during the Passive Monitored Period. The analysis included the thermal properties of the building envelope, geometric parameters, ratios and others passive solutions such as Thermal Energy Storage systems, evaporative cooling, night ventilation, solar gains and night sky radiation cooling. The results reflect the impact of passive design strategies on the houses' comfort and efficiency, as well as their influence in helping to achieve the Zero Energy Buildings category.

La implementaci��n arquitect��nica de los acristalamientos activos con agua circulante, y su contribuci��n en edificios de consumo de energ��a casi nulo

La presente Tesis Doctoral eval��a la contribuci��n de una fachada activa, constituida por acristalamientos con circulaci��n de agua, en el rendimiento energ��tico del edificio. Con especial ��nfasis en la baja afecci��n sobre su imagen, su integraci��n ha de favorecer la calificaci��n del edificio con el futuro est��ndar de Edificio de consumo de Energ��a Casi Nulo (EECN). El prop��sito consiste en cuantificar su aportaci��n a limitar la demanda de climatizaci��n, como soluci��n de fachada transparente acorde a las normas de la energ��a del 2020. En el primer cap��tulo se introduce el planteamiento del problema. En el segundo cap��tulo se desarrollan la hip��tesis y el objetivo fundamental de la investigaci��n. Para tal fin, en el tercer cap��tulo, se revisa el estado del arte de la tecnolog��a y de la investigaci��n cient��fica, mediante el an��lisis de la literatura de referencia. Se comparan patentes, prototipos, sistemas comerciales asimilables, investigaciones en curso en Universidades, y proyectos de investigaci��n y desarrollo, sobre envolventes que incorporan acristalamientos con circulaci��n de agua. El m��todo experimental, expuesto en el cuarto cap��tulo, acomete el dise��o, la fabricaci��n y la monitorizaci��n de un prototipo expuesto, durante ciclos de ensayos, a las condiciones clim��ticas de Madrid. Esta fase ha permitido adquirir informaci��n precisa sobre el rendimiento del acristalamiento en cada orientaci��n de incidencia solar, en las distintas estaciones del a��o. En paralelo, se aborda el desarrollo de modelos te��ricos que, mediante su asimilaci��n a soluciones multicapa caracterizadas en las herramientas de simulaci��n EnergyPlus y IDA-ICE (IDA Indoor Climate and Energy), reproducen el efecto experimental. En el quinto cap��tulo se discuten los resultados experimentales y te��ricos, y se analiza la respuesta del acristalamiento asociado a un determinado volumen y temperatura del agua. Se calcula la eficiencia en la captaci��n de la radiaci��n y, mediante la comparativa con un acristalamiento convencional, se determina la reducci��n de las ganancias solares y las p��rdidas de energ��a. Se comparan el rendimiento del acristalamiento, obtenido experimentalmente, con el ofrecido por paneles solares fotot��rmicos disponibles en el mercado. Mediante la traslaci��n de los resultados experimentales a casos de c��lulas de tama��o habitable, se cuantifica la afecci��n del acristalamiento sobre el consumo en refrigeraci��n y calefacci��n. Diferenciando cada caso por su composici��n constructiva y orientaci��n, se extraen conclusiones sobre la reducci��n del gasto en climatizaci��n, en condiciones de bienestar. Posteriormente, se eval��a el ahorro de su incorporaci��n en un recinto existente, de construcci��n ligera, localizado en la Escuela de Arquitectura de la Universidad Polit��cnica de Madrid (UPM). Mediante el planteamiento de escenarios de rehabilitaci��n energ��tica, se estima su compatibilidad con un sistema de climatizaci��n mediante bomba de calor y extracci��n geot��rmica. Se describe el funcionamiento del sistema, desde la perspectiva de la operaci��n conjunta de los acristalamientos activos e intercambio geot��rmico, en nuestro clima. Mediante la parametrizaci��n de sus funciones, se estima el beneficio adicional de su integraci��n, a partir de la mejora del rendimiento de la bomba de calor COP (Coefficient of Performance) en calefacci��n, y de la eficiencia EER (Energy Efficiency Ratio) en refrigeraci��n. En el recinto de la ETSAM, se ha analizado la contribuci��n de la fachada activa en su calificaci��n como Edificio de Energ��a Casi Nula, y estudiado la rentabilidad econ��mica del sistema. En el sexto cap��tulo se exponen las conclusiones de la investigaci��n. A la fecha, el sistema supone alta inversi��n inicial, no obstante, genera elevada eficiencia con bajo impacto arquitect��nico, reduci��ndose los costes operativos, y el dimensionado de los sistemas de producci��n, de mayor afecci��n sobre el edificio. Mediante la envolvente activa con suministro geot��rmico no se condena la superficie de cubierta, no se ocupa volumen ��til por la presencia de equipos emisores, y no se reduce la superficie o altura ��til a base de reforzar los aislamientos. Tras su discusi��n, se considera una alternativa de valor en procesos de dise��o y construcci��n de Edificios de Energ��a Casi Nulo. Se proponen l��neas de futuras investigaci��n cuyo prop��sito sea el conocimiento de la tecnolog��a de los acristalamientos activos. En el ��ltimo cap��tulo se presentan las actividades de difusi��n de la investigaci��n. Adicionalmente se ha proporcionado una mejora tecnol��gica a las fachadas activas existentes, que ha derivado en la solicitud de una patente, actualmente en tramitaci��n. ABSTRACT This Thesis evaluates the contribution of an active water flow glazing fa��ade on the energy performance of buildings. Special emphasis is made on the low visual impact on its image, and the active glazing implementation has to encourage the qualification of the building with the future standard of Nearly Zero Energy Building (nZEB). The purpose is to quantify the fa��ade system contribution to limit air conditioning demand, resulting in a transparent fa��ade solution according to the 2020 energy legislation. An initial approach to the problem is presented in first chapter. The second chapter develops the hypothesis and the main objective of the research. To achieve this purpose, the third chapter reviews the state of the art of the technology and scientific research, through the analysis of reference literature. Patents, prototypes, assimilable commercial systems, ongoing research in other universities, and finally research and development projects incorporating active fluid flow glazing are compared. The experimental method, presented in fourth chapter, undertakes the design, manufacture and monitoring of a water flow glazing prototype exposed during test cycles to weather conditions in Madrid. This phase allowed the acquisition of accurate information on the performance of water flow glazing on each orientation of solar incidence, during different seasons. In parallel, the development of theoretical models is addressed which, through the assimilation to multilayer solutions characterized in the simulation tools EnergyPlus and IDA-Indoor Climate and Energy, reproduce the experimental effect. Fifth chapter discusses experimental and theoretical results focused to the analysis of the active glazing behavior, associated with a specific volume and water flow temperature. The efficiency on harvesting incident solar radiation is calculated, and, by comparison with a conventional glazing, the reduction of solar gains and energy losses are determined. The experimental performance of fluid flow glazing against the one offered by photothermal solar panels available on the market are compared. By translating the experimental and theoretical results to cases of full-size cells, the reduction in cooling and heating consumption achieved by active fluid glazing is quantified. The reduction of energy costs to achieve comfort conditions is calculated, differentiating each case by its whole construction composition and orientation. Subsequently, the saving of the implementation of the system on an existing lightweight construction enclosure, located in the School of Architecture at the Polytechnic University of Madrid (UPM), is then calculated. The compatibility between the active fluid flow glazing and a heat pump with geothermal heat supply system is estimated through the approach of different energy renovation scenarios. The overall system operation is described, from the perspective of active glazing and geothermal heat exchange combined operation, in our climate. By parameterization of its functions, the added benefit of its integration it is discussed, particularly from the improvement of the heat pump performance COP (Coefficient of Performance) in heating and efficiency EER (Energy Efficiency Ratio) in cooling. In the case study of the enclosure in the School of Architecture, the contribution of the active glazing fa��ade in qualifying the enclosure as nearly Zero Energy Building has been analyzed, and the feasibility and profitability of the system are studied. The sixth chapter sets the conclusions of the investigation. To date, the system may require high initial investment; however, high efficiency with low architectural impact is generated. Operational costs are highly reduced as well as the size and complexity of the energy production systems, which normally have huge visual impact on buildings. By the active fa��ade with geothermal supply, the deck area it is not condemned. Useful volume is not consumed by the presence of air-conditioning equipment. Useful surface and room height are not reduced by insulation reinforcement. After discussion, water flow glazing is considered a potential value alternative in nZEB design and construction processes. Finally, this chapter proposes future research lines aiming to increase the knowledge of active water flow glazing technology. The last chapter presents research dissemination activities. Additionally, a technological improvement to existing active facades has been developed, which has resulted in a patent application, currently in handling process.