Integral energy performance characterization of semi-transparent photovoltaic elements for building integration under real operation conditions

In this paper, a methodology for the integral energy performance characterization (thermal, daylighting and electrical behavior) of semi-transparent photovoltaic modules (STPV) under real operation conditions is presented. An outdoor testing facility to analyze simultaneously thermal, luminous and electrical performance of the devices has been designed, constructed and validated. The system, composed of three independent measurement subsystems, has been operated in Madrid with four prototypes of a-Si STPV modules, each one corresponding to a specific degree of transparency. The extensive experimental campaign, continued for a whole year rotating the modules under test, has validated the reliability of the testing facility under varying environmental conditions. The thermal analyses show that both the solar protection and insulating properties of the laminated prototypes are lower than those achieved by a reference glazing whose characteristics are in accordance with the Spanish Technical Building Code. Daylighting analysis shows that STPV elements have an important lighting energy saving potential that could be exploited through their integration with strategies focused to reduce illuminance values in sunny conditions. Finally, the electrical tests show that the degree of transparency is not the most determining factor that affects the conversion efficiency.

Energy saving potential of semi-transparent photovoltaic elements for building integration

Within the building energy saving strategies, BIPV (building integrated photovoltaic systems) present a promising potential based on the close relationship existing between these multifunctional systems and the overall building energy balance. Building integration of STPV (semi-transparent photovoltaic) elements affects deeply the building energy demand since it influences the heating, cooling and lighting loads as well as the local electricity generation. This work analyses over different window-to-wall ratios the overall energy performance of five STPV elements, each element having a specific degree of transparency, in order to assess the energy saving potential compared to a conventional solar control glass compliant with the local technical standard. The prior optical characterization, focused to measure the spectral properties of the elements, was experimentally undertaken. The obtained data were used to perform simulations based on a reference office building using a package of specific software tools (DesignBuilder, EnergyPlus, PVsyst, and COMFEN) to take proper account of the STPV peculiarities. To evaluate the global energy performance of the STPV elements a new Energy Balance Index was formulated. The results show that for intermediate and large façade openings the energy saving potential provided by the STPV solutions ranges between 18% and 59% compared to the reference glass.

Energy-consistent time integration for nonlinear viscoelasticity

This work is concerned with the numerical solution of the evolution equations of thermomechanical systems, in such a way that the scheme itself satisfies the laws of thermodynamics. Within this framework, we present a novel integration scheme for the dynamics of viscoelastic continuum bodies in isothermal conditions. This method intrinsically satisfies the laws of thermodynamics arising from the continuum, as well as the possible additional symmetries. The resulting solutions are physically accurate since they preserve the fundamental physical properties of the model. Furthermore, the method gives an excellent performance with respect to robustness and stability. Proof for these claims as well as numerical examples that illustrate the performance of the novel scheme are provided

Integral energy behaviour of photovoltaic semi-transparent glazing elements for building integration

La hipótesis general que esta tesis quiere demostrar es que la integración arquitectónica de sistemas fotovoltaicos semitransparentes (STPV) puede contribuir a mejorar la eficiencia energética de los edificios. Por lo tanto, la investigación se centra en el desarrollo de una metodología capaz de cuantificar la reducción de la demanda energética del edificio proporcionada por estas novedosas soluciones constructivas. Al mismo tiempo, los parámetros de diseño de las soluciones STPV se han analizado para establecer cuales presentan el mayor impacto sobre el balance energético global del edificio y por lo tanto tienen que ser cuidadosamente definidos a la hora de optimizar el comportamiento energético del mismo. A la luz de estos objetivos, la metodología de estudio se ha centrado en tres puntos principales:  Caracterizar el comportamiento energético global de sistemas STPV en condiciones de operación realistas, similares a las que se darían en un sistema real;  Caracterizar el comportamiento energético global de sistemas STPV en condiciones controladas, con el objetivo de estudiar la variación del comportamiento del los elementos en función de parámetro de diseño y operación;  Evaluar el potencial de ahorro energético global de los sistemas STPV en comparación con soluciones acristaladas convencionales al variar de las condiciones de contorno constituidas por los parámetros de diseño (como el grado de transparencia), las características arquitectónicas (como el ratio entre superficie acristalada y superficie opaca en la fachada del edificio) y las condiciones climáticas (cubriendo en particular la climatología europea). En síntesis, este trabajo intenta contribuir a comprender la interacción que existe entre los sistemas STPV y el edificio, proporcionando tanto a los fabricantes de los componentes como a los profesionales de la construcción información valiosa sobre el potencial de ahorro energético asociado a estos nuevos sistemas constructivos. Asimismo el estudio define los parámetros de diseño adecuados para lograr soluciones eficientes tanto en proyectos nuevos como de rehabilitación. ABSTRACT The general hypothesis this work seeks to demonstrate is that the architectural integration of Semi-Transparent Photovoltaic (STPV) systems can contribute to improving the energy efficiency of buildings. Accordingly, the research has focused on developing a methodology able to quantify the building energy demand reduction provided by these novel constructive solutions. At the same time, the design parameters of the STPV solution have been analysed to establish which of them have the greatest impact on the global energy balance of the building, and therefore which have to be carefully defined in order to optimize the building operation. In the light of these goals, the study methodology has focused on three main points:  To characterise the global energy behaviour of STPV systems in realistic operating conditions, similar to those in which a real system will operate;  To characterise the global energy behaviour of STPV systems in controlled conditions in order to study how the performance varies depending on the design and operating parameters;  To assess the global energy saving potential of STPV systems in comparison with conventional glazing solutions by varying the boundary conditions, including design parameters (such as the degree of transparency), architectural characteristics (such as the Window to Wall Ratio) and climatic conditions (covering the European climatic conditions). In summary, this work has sought to contribute to the understanding of the interaction between STPV systems and the building, providing both components manufacturers and construction technicians, valuable information on the energy savings potential of these new construction systems and defining the appropriate design parameters to achieve efficient solutions in both new and retrofitting projects.

Energy-entropy-momentum time integration methods for coupled smooth dissipative problems

Esta tesis aborda la formulación, análisis e implementación de métodos numéricos de integración temporal para la solución de sistemas disipativos suaves de dimensión finita o infinita de manera que su estructura continua sea conservada. Se entiende por dichos sistemas aquellos que involucran acoplamiento termo-mecánico y/o efectos disipativos internos modelados por variables internas que siguen leyes continuas, de modo que su evolución es considerada suave. La dinámica de estos sistemas está gobernada por las leyes de la termodinámica y simetrías, las cuales constituyen la estructura que se pretende conservar de forma discreta. Para ello, los sistemas disipativos se describen geométricamente mediante estructuras metriplécticas que identifican claramente las partes reversible e irreversible de la evolución del sistema. Así, usando una de estas estructuras conocida por las siglas (en inglés) de GENERIC, la estructura disipativa de los sistemas es identificada del mismo modo que lo es la Hamiltoniana para sistemas conservativos. Con esto, métodos (EEM) con precisión de segundo orden que conservan la energía, producen entropía y conservan los impulsos lineal y angular son formulados mediante el uso del operador derivada discreta introducido para asegurar la conservación de la Hamiltoniana y las simetrías de sistemas conservativos. Siguiendo estas directrices, se formulan dos tipos de métodos EEM basados en el uso de la temperatura o de la entropía como variable de estado termodinámica, lo que presenta importantes implicaciones que se discuten a lo largo de esta tesis. Entre las cuales cabe destacar que las condiciones de contorno de Dirichlet son naturalmente impuestas con la formulación basada en la temperatura. Por último, se validan dichos métodos y se comprueban sus mejores prestaciones en términos de la estabilidad y robustez en comparación con métodos estándar. This dissertation is concerned with the formulation, analysis and implementation of structure-preserving time integration methods for the solution of the initial(-boundary) value problems describing the dynamics of smooth dissipative systems, either finite- or infinite-dimensional ones. Such systems are understood as those involving thermo-mechanical coupling and/or internal dissipative effects modeled by internal state variables considered to be smooth in the sense that their evolutions follow continuos laws. The dynamics of such systems are ruled by the laws of thermodynamics and symmetries which constitutes the structure meant to be preserved in the numerical setting. For that, dissipative systems are geometrically described by metriplectic structures which clearly identify the reversible and irreversible parts of their dynamical evolution. In particular, the framework known by the acronym GENERIC is used to reveal the systems' dissipative structure in the same way as the Hamiltonian is for conserving systems. Given that, energy-preserving, entropy-producing and momentum-preserving (EEM) second-order accurate methods are formulated using the discrete derivative operator that enabled the formulation of Energy-Momentum methods ensuring the preservation of the Hamiltonian and symmetries for conservative systems. Following these guidelines, two kind of EEM methods are formulated in terms of entropy and temperature as a thermodynamical state variable, involving important implications discussed throughout the dissertation. Remarkably, the formulation in temperature becomes central to accommodate Dirichlet boundary conditions. EEM methods are finally validated and proved to exhibit enhanced numerical stability and robustness properties compared to standard ones.

Deploying the energy incentive: reinforcing EU integration in South-East Europe. CEPS Policy Brief No. 296, July 2013

This Policy Brief urges the European Union to consider reinforcing the Energy Community by further Europeanising the Energy Community Treaty. It argues that the level of dysfunctionality with respect to the rule of law and corruption will make it very hard to establish a pathway for accession for most Balkan states. However, the demand across the region for a sustainable, competitive and stable energy sector creates an ‘energy incentive’ that the Union can leverage to improve the rule of law and adherence to European rules. Furthermore, a juridical strengthening of the Energy Community Treaty will also strengthen the hand of those parties supporting energy liberalisation rules across the region, such as independent businesses, consumers and NGOs. In addition, there is likely to be significant spill-over effects from decisions of a European Energy Community Court operating in the region on the rule of law in general and the accession process in particular.

Between energy security and energy market integration. Guidelines for the future development of the EU’s external energy policy in Europe’s neighbourhood. OSW Report, June 2011

For many years the European Union has been improving the efficient use of energy resources and yet the demand for energy in the EU continues to increase. When Europe belonged to one of the world’s key energy markets with relatively easy access to energy resources, growing energy needs were not seen as a source of concern. Today, however, as the competition for energy resources is intensifying and the global position of the EU energy market is being challenged by growing economies in the developing countries, above all China and India, the EU needs to adopt bold policies to guarantee the sustainable supply of energy. This report argues the EU needs to develop a fully-fledged external energy policy; i.e. a common, coherent, strategic approach that build bridges between the interests and needs of the EU integrated energy market on the one hand and supplier countries on the other. The EU’s external energy policy has two main objectives. The first one is to ensure a sustainable, stable and cost-effective energy supply. The second is to promote energy market integration and regulatory convergence with neighbouring countries (often but not always this supports the achievement of the first objective). However, in order to improve its effectiveness, the EU’s external energy policy needs to be seen in a broader economic and political context. Any progress in energy cooperation with third countries is contingent upon the EU’s general stance and offer to those countries.

EU climate and energy policy: hope for more and better climate policy integration? IES Policy Brief Issue 2014/02/January 2014

Summary. With discussions on-going in the EU on the climate and energy policy framework to 2030, it is timely to assess the reality of climate policy integration into EU energy policy. Such an analysis can lead to lessons for the legislative process for the 2030 package, and even for policies in other sectors and beyond 2030. Climate change is a complex, crosscutting, long-term and global problem. Policymakers acknowledge that integrating climate policy objectives into the elaboration and agreement of measures in other sectors represents one method for striving towards coherent policies that respond adequately to the climate change problem. This policy brief presents the results and policy recommendations from the project “climate policy integration into EU energy policy”.

Energy related innovation, the missing link? : a revision and integration of the business cycle theories of Keynes and Schumpeter /

"To be presented at the Sixteenth International Atlantic Economic Conference, Philadelphia, Pennsylvania, October 6-9, 1983."