F2TE3: A Transparent semi-monocoque VIP Envelope

This article examines a new lightweight, slim, high energy efficient, light-transmitting, self-supporting envelope system, providing for seamless, free-form designs for use in architectural projects. The system exploits vacuum insulation panel technology. The research was based on envelope components already existing on the market and patents and prototypes built by independent laboratories, especially components implemented with silica gel insulation, as this is the most effective transparent thermal insulation there is today. The tests run on these materials revealed that there is not one that has all the features required of the new envelope model, although some do have properties that could be exploited to generate this envelope, namely, the vacuum chamber of vacuum insulation panels, the use of monolithic aerogel as insulation in some prototypes, and reinforced polyester barriers. These three design components have been combined and tested to design a new, variable geometry, energy-saving envelope system that also solves many of the problems that other studies ascribe to the use of vacuum insulation panels.

The use of arc-erosion as a patterning technique for transparent conductive materials

Within the framework of cost-effective patterning processes a novel technique that saves photolithographic processing steps, easily scalable to wide area production, is proposed. It consists of a tip-probe, which is biased with respect to a conductive substrate and slides on it, keeping contact with the material. The sliding tip leaves an insulating path (which currently is as narrow as 30 μm) across the material, which enables the drawing of tracks and pads electrically insulated from the surroundings. This ablation method, called arc-erosion, requires an experimental set up that had to be customized for this purpose and is described. Upon instrumental monitoring, a brief proposal of the physics below this process is also presented. As a result an optimal control of the patterning process has been acquired. The system has been used on different substrates, including indium tin oxide either on glass or on polyethylene terephtalate, as well as alloys like Au/Cr, and Al. The influence of conditions such as tip speed and applied voltage is discussed

Free-Form, High Energy Performance, Transparent Vacuum Envelope

El artículo examina un nuevo sistema envolvente ligero, delgado, con ahorro energético, libre de formas diseñado para su uso en proyectos de arquitectura.

F2TE3: A Transparent semi-monocoque VIP Envelope

This article examines a new lightweight, slim, high energy efficient, light-transmitting, selfsupporting envelope system, providing for seamless, free-form designs for use in architectural projects. The system exploits vacuum insulation panel technology. The research was based on envelope components already existing on the market and patents and prototypes built by independent laboratories, especially components implemented with silica gel insulation, as this is the most effective transparent thermal insulation there is today.

Free-Form, High Energy Performance, Transparent Envelope

This article examines, from the energy viewpoint, a new lightweight, slim, high energy efficient, light-transmitting envelope system, providing for seamless, free-form designs for use in architectural projects. The research was based on envelope components already existing on the market, especially components implemented with granular silica gel insulation, as this is the most effective translucent thermal insulation there is today. The tests run on these materials revealed that there is not one that has all the features required of the new envelope model, although some do have properties that could be exploited to generate this envelope, namely, the vacuum chamber of vacuum insulated panels (VIP), the monolithic aerogel used as insulation in some prototypes, reinforced polyester barriers. By combining these three design components — the high-performance thermal insulation of the vacuum chamber combined with monolithic silica gel insulation, the free-form design potential provided by materials like reinforced polyester and epoxy resins—, we have been able to define and test a new, variable geometry, energy-saving envelope system.

F²TE³: A Transparent semi-monocoque VIP Envelope

This article examines a new lightweight, slim, high energy efficient, light-transmitting, self-supporting envelope system, providing for seamless, free-form designs for use in architectural projects. The system exploits vacuum insulation panel technology. The research was based on envelope components already existing on the market and patents and prototypes built by independent laboratories, especially components implemented with silica gel insulation, as this is the most effective transparent thermal insulation there is today. The tests run on these materials revealed that there is not one that has all the features required of the new envelope model, although some do have properties that could be exploited to generate this envelope, namely, the vacuum chamber of vacuum insulation panels, the use of monolithic aerogel as insulation in some prototypes, and reinforced polyester barriers. These three design components have been combined and tested to design a new, variable geometry, energy-saving envelope system that also solves many of the problems that other studies ascribe to the use of vacuum insulation panels.

Electrophoretic Deposition of Transparent ZnO Thin Films from Highly Stabilized Colloidal Suspensions

The parameters that control the stability of ZnO-nanoparticles suspensions and their deposition by electrophoretic deposition were studied, so as to organize the assembly and compaction of nanoparticles. The addition of cationic polyelectrolyte - Polyethylenimine (PEI) - with different molecular weights was investigated, in order to study their effectiveness and the influence of the molecular weight of the organic chain on suspensions dispersion. It was found that PEI with the highest molecular weight provided better dispersion conditions. Cathodic EPD was performed under previously optimized suspensions conditions and over electropolished stainless steel substrates. Experimental results showed that the EPD process in these conditions allows obtaining dense transparent ZnO thin films. Deposition times and intensities were optimized by analyzing the resulting thin films characteristics. Finally, the deposits were characterized by FE-SEM, AFM, and different spectroscopic techniques.

Design, development and construction of an outdoor testing facility for semi-transparent photovoltaic modules

Building-integrated Photovoltaics (BIPV) is one of the most promising technologies enabling buildings to generate on-site part of their electricity needs while performing architectural functionalities. A clear example of BIPV products consists of semi-transparent photovoltaic modules (STPV), designed to replace the conventional glazing solutions in building façades. Accordingly, the active building envelope is required to perform multiple requirements such as provide solar shading to avoid overheating, supply solar gains and thermal insulation to reduce heat loads and improve daylight utilization. To date, various studies into STPV systems have focused on their energy performance based on existing simulation programs, or on the modelling, normally validated by limited experimental data, of the STPV modules thermal behaviour. Taking into account that very limited experimental research has been conducted on the energy performance of STPV elements and that the characterization in real operation conditions is necessary to promote an energetically efficient integration of this technology in the building envelope, an outdoor testing facility has been designed, developed and built at the Solar Energy Institute of the Technical University of Madrid. In this work, the methodology used in the definition of the testing facility, its capability and limitations are presented and discussed.

Optical characterisation of semi-transparent PV modules for building integration

A complete characterisation of PV modules for building integration is needed in order to know their influence on the building’s global energy balance. Specifically, certain characteristic parameters should be obtained for each different PV module suitable for building integrated photovoltaics (BIPV), some by direct or indirect measurements at the laboratory, and others by monitoring the element performance mounted in real operating conditions. In the case of transparent building envelopes it is particularly important to perform an optical and thermal characterization of the PV modules that would be integrated in them. This paper addresses the optical characterization of some commercial thin-film PV modules having different degrees of transparency, suitable for building integration in façades. The approach is based on the measurement of the spectral UV/Vis/NIR reflectance and transmittance of the different considered samples, both at normal incidence and as a function of the angle of incidence. With the obtained results, the total and zoned UV, visible and NIR transmission and reflection values are calculated, enabling the correct characterization of the PV modules integrated in façades and the subsequent evaluation of their impact over the electrical, thermal and lighting performance in a building.

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.

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.