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Lollini R.,Institute for Renewable Energy | Danza L.,CNR Construction Technologies Institute | Meroni I.,CNR Construction Technologies Institute
Solar Energy | Year: 2010

The reduction of air-conditioning energy consumptions is one of the main indicators to act on when improving the energy efficiency in buildings. In the case of advanced technological buildings, a meaningful contribution to the thermal loads and the energy consumptions reduction could depend on the correct configuration and management of the envelope systems. In recent years, the architectural trend toward highly transparent all-glass buildings presents a unique challenge and opportunity to advance the market for emerging, smart, dynamic window and dimmable daylighting control technologies (Lee et al., 2004). A prototype dynamic glazing system was developed and tested at ITC-CNR; it is aimed at actively responding to the external environmental loads. Both an experimental campaign and analyses by theoretical models were carried out, aimed at evaluating the possible configurations depending on different weather conditions in several possible places. Therefore, the analytical models of the building-plant system were defined by using a dynamic energy simulation software (EnergyPlus). The variables that determine the system performance, also influenced by the boundary conditions, were analysed, such as U- and g-value; they concern both the morphology of the envelope system, such as dimensions, shading and glazing type, gap airflow thickness, in-gap airflow rate, and management, in terms of control algorithm parameters tuning fan and shading systems, as a function of the weather conditions. The configuration able to provide the best performances was finally identified by also assessing such performances, integrating the dynamic system in several building types and under different weather conditions. The dynamic envelope system prototype has become a commercial product with some applications in façade systems, curtain walls and windows. The paper describes the methodological approach to prototype development and the main results obtained, including simulations of possible applications on real buildings. © 2009 Elsevier Ltd. All rights reserved.

D'Antoni M.,Institute for Renewable Energy | Saro O.,University of Udine
Solar Energy | Year: 2013

The aim of this work is to investigate the energy potential of using exposed concrete structures as solar energy absorbers (here denoted with the general term of Massive Solar-Thermal Collectors, MSTCs) during the heating period and in particular the design of a Concrete Solar Collector (CSC) is then presented. The CSC is a particular kind of MSTC, conceived as an exposed free standing structure that embeds a coiled pipe heat exchanger in a massive-concrete matrix. A numerical design model has been developed and parametric simulations have been conducted in order to get a figure of the energy potential of the CSC under different European climate conditions. The CSC has reached an energy yield of 460.77kWh/m2/y and an average heat flux of 93.07W/m2 for the reference climate of Stuttgart (Germany) during the winter season (inlet fluid temperature of -5°C and mass-flow rate of 45kg/h/m2). The Elementary Effect Method has been adopted as Sensitivity Analysis procedure with the aim of understanding the dependency of design parameters on the energy output. Finally, an economic analysis has been carried out by comparing investment costs and energy outputs. © 2013 Elsevier Ltd.

Noris F.,Institute for Renewable Energy | Musall E.,University of Wuppertal | Salom J.,Catalonia Institute for Energy Research IREC | Berggren B.,Lund University | And 3 more authors.
Energy and Buildings | Year: 2014

With the current movement towards Net Zero Energy Buildings (Net ZEBs) decisions regarding energy carrier weighting factors will have implications on which technologies could be favoured or disfavoured, and therefore adopted or not adopted, in the building sector of the near future. These implications should be taken into consideration by policy makers when developing legislation and regulations addressing the building sector. A parametric analysis was conducted on six buildings in Europe of different typologies and climates in order to assess how different weighting factors would impact the choice of technical systems to be installed. For each combination the amount of PV capacity necessary to achieve a net zero balance has been calculated and used as the main indicator for comparison; where less PV area means more favourable condition. The effect of including a solar thermal system is also discussed. With the current European national weighting factors, biomass boiler is largely the preferred solution, frequently achieving the balance with PV installed on the roof, while gas boiler is the most penalized. The situation changes when strategic weighting factors are applied. Lower weighting factors for electricity and district heating, e.g. reflecting national targets of increased penetration of renewables in such grids, would promote the use of heat pump and district heating, respectively. Asymmetric factors aimed at rewarding electricity export to the grid would facilitate the achievement of the zero balance for all technologies, promoting cogeneration in some cases. On the contrary, low weighting factors for electricity, e.g. reflecting a scenario of high decarbonisation of the power system, prove quite demanding; only few technical solutions would be able to reach the balance within the available roof area for PV, because of the low value credited to exported electricity. In this situation, the preferred solution would be heat pumps combined with solar thermal. In addition, the choice of weighting factors and the resulting favoured technologies will determine the temporal matching of load and generation. While all-electric solutions tend to use the grid as seasonal storage, other solutions will have a yearly net export of electricity to the grid to compensate for the supply of other (thermal) energy carriers. Therefore, it is important to consider the implications for the electricity grid resulting from the choice of weighting factors. © 2014 Elsevier B.V.

Marszal A.J.,University of Aalborg | Heiselberg P.,University of Aalborg | Bourrelle J.S.,Norwegian University of Science and Technology | Musall E.,University of Wuppertal | And 3 more authors.
Energy and Buildings | Year: 2011

The concept of Zero Energy Building (ZEB) has gained wide international attention during last few years and is now seen as the future target for the design of buildings. However, before being fully implemented in the national building codes and international standards, the ZEB concept requires clear and consistent definition and a commonly agreed energy calculation methodology. The most important issues that should be given special attention before developing a new ZEB definition are: (1) the metric of the balance, (2) the balancing period, (3) the type of energy use included in the balance, (4) the type of energy balance, (5) the accepted renewable energy supply options, (6) the connection to the energy infrastructure and (7) the requirements for the energy efficiency, the indoor climate and in case of gird connected ZEB for the building-grid interaction. This paper focuses on the review of the most of the existing ZEB definitions and the various approaches towards possible ZEB calculation methodologies. It presents and discusses possible answers to the abovementioned issues in order to facilitate the development of a consistent ZEB definition and a robust energy calculation methodology. © 2011 Elsevier B.V. All rights reserved.

Colli A.,Institute for Renewable Energy | Colli A.,Brookhaven National Laboratory | Zaaiman W.J.,European Commission - Joint Research Center Ispra
IEEE Journal of Photovoltaics | Year: 2012

This paper presents springtime monitoring results for different crystalline-silicon (c-Si) photovoltaic (PV) systems installed at the multitechnology ground-mounted PV test field at the Airport Bolzano Dolomiti (ABD) located in the Italian Alps. The system data are analyzed and discussed.The main purpose of this paper is to validate the performance evaluation through a methodology based on the effective maximum power of the PV modules. This approach could be useful when dealing, as in the present case, with commercial monitoring systems. Three different silicon-based technologies are taken into consideration: polycrystalline silicon, high-efficiency monocrystalline silicon, and hybrid monocrystalline silicon that have been positioned both on a single-axis tracker and on fixed 30 °-tilted supports. The systems are connected to different types of inverter, through which the power monitoring is performed. The assessment shows indicators, such as final yield and performance ratio, for both tracked and fixed-tilt systems. The PV systems are evaluated in relation to irradiance data registered by two identical c-Si reference devices positioned on the tracker and on the fixed supports. Results show that an average difference of ±14 W exists between the module's label and the actual peak power. This difference is in line with the power tolerance declared by manufacturers. The maximum-power-based PV performance validation method could initially highlight cases in which a faulty module hides in the system, having the potential for application in fault detection and reliability analysis, followed by more specific evaluations. © 2012 IEEE.

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