Accounting for local impacts of photovoltaic farms: two stated preferences approaches

Renewable energy sources for electricity generation are unequivocally more environmentally friendly than the traditional sources, but are not impact-free. Given the potential for solar photovoltaic energy to contribute to the energy mix in some countries, it is timely to carefully consider the potential environmental costs of operation of photovoltaic farms, which are experienced by the local population, while the general benefits accrue to all. These adverse impacts should be identified and acknowledged. This paper proposes and applies economic valuation methods to estimate the value of those environmental impacts. We apply the contingent valuation method to a sample of local residents close to three selected photovoltaic farms in Portugal. We design a discrete choice experiment to elicit the valuation of specific adverse impacts of electricity generation through photovoltaic energy by national residents. Our results show that the value elicited in the vicinity of the photovoltaic farms is non-negligible and national residents value positively and differently the different adverse local impacts. Both of these estimates, in conjunction or independently, can be used to fully account for this often neglected cost of solar energy. The asymmetric equity implications of photovoltaic projects should not be neglected when deciding their construction and location.PTDC/EGEECO/122402/201

Aesthetic impact of solar energy systems

The presence of solar energy systems has increased significantly in recent years both in rural areas –in the form of solar farms–, and in urban areas as part of building installations. This transformation of the landscape, in spite of the good social acceptance of solar energy, causes an aesthetic impact whose interest has been growing in literature in recent years. This study aimed to review prior literature in order to establish the objective factors, aesthetic perception and methods that are most relevant when assessing the aesthetic impact. As a result of the lack of consensus, a new qualitative theoretical framework is proposed that can serve as a basis for future research in the field of the integration of solar energy and its aesthetic impact. The framework comprises three sub-impacts: land use, solar system energy and glare. The results are discussed for future research and innovation in building photovoltaic integration and for SES site location and its environmental impact assessments

Molten Salts as Heat Transfer Fluids for Solar Thermal Power Plants

Carbon dioxide, primarily created by burning fossil fuels, is an overwhelming component to the global warming problem. With these environmental issues surrounding fossil fuels, it is important to fully develop alternative energy options. Solar thermal power is a viable solution to the world's energy problem and is an environmentally friendly and safe solution. The purpose of this thesis is to determine melting temperature, heat capacity and density of molten salts and investigate their viability as a heat transfer fluid for a solar thermal power plant. The solar thermal power plant model developed by Powell and Edgar [1] was utilized and altered to implement the properties determined for NaCl, KCl and a NaCl-KCl mixture. The unit cell structures for each were developed in MATLAB to determine the necessary material properties for the solar thermal power plant simulation. The melting temperature was determined using Tosi-Fumi interaction potentials. Using the simulation results for the melting temperature, the heat capacity and density were determined for the molten salts' melt and crystal structures. The parameters of NaCl and KCl were used in the power plant simulation to study their effect on power. Both molten salts did not perform as well as the original molten salt used by Powell and Edgar. An additional study was conducted to determine the effects of density and heat capacity on power. As anticipated, a higher heat capacity increases the power output, whereas density does not affect the power output. Due to the low heat capacities of NaCl and KCl, these are not realistic options for heat storage. Overall, molten salts possess high thermal stability and high thermal conductivities. The simulations created in this study provide the building blocks for future work in more complex molten salts, such as solar salt, Hitec and Hitec XL.M.S., Materials Science -- Drexel University, 201

Experimental Assessment of the Reflection of Solar Radiation from Façades of Tall Buildings to the Pedestrian Level

Urban climates are highly influenced by the ability of built surfaces to reflect solar radiation, and the use of high-albedo materials has been widely investigated as an effective option to mitigate urban overheating. While diffusely solar reflective walls have attracted concerns in the architectural and thermal comfort community, the potential of concave and polished surfaces, such as glass and metal panels, to cause extreme glare and localized thermal stress has been underinvestigated. Furthermore, there is the need for a systematic comparison of the solar concentration at the pedestrian level in front of tall buildings. Herein, we show the findings of an experimental campaign measuring the magnitude of the sunlight reflected by scale models reproducing archetypical tall buildings. Three 1:100 scaled prototypes with different shapes (classic vertical façade, 10% tilted façade, curved concave façade) and different finishing materials (representative of extremes in reflectance properties of building materials) were assessed. A specular surface was assumed as representative of a glazed façade under high-incidence solar angles, while selected light-diffusing materials were considered sufficient proxies for plaster finishing. With a diffusely reflective façade, the incident radiation at the pedestrian level in front of the building did not increase by more than 30% for any geometry. However, with a specular reflective (i.e., mirror-like) flat façade, the incident radiation at the pedestrian level increased by more than 100% and even by more than 300% with curved solar-concentrating geometries. In addition, a tool for the preliminary evaluation of the solar reflectance risk potential of a generic complex building shape is developed and presented. Our findings demonstrate that the solar concentration risk due to mirror-like surfaces in the built environment should be a primary concern in design and urban microclimatology

The dark side of photovoltaic : 3D simulation of glare assessing risk and discomfort

Photovoltaic (PV) systems form an important force in the implementation of renewable energies, but as we all know, the force has always its dark side. Besides efficiency considerations and discussions about architectures of power distribution networks, the increasing numbers of installations of PV systems for implementing renewable energies have secondary effects. PV systems can generate glare due to optical reflections and hence might be a serious concern. On the one hand, glare could affect safety, e.g. regarding traffic. On the other hand, glare is a constant source of discomfort in vicinities of PV systems. Hence, assessment of glare is decisive for the success of renewable energies near municipalities and traffic zones for the success of solar power. Several courts decided on the change of PV systems and even on their de-installation because of glare effects. Thus, location-based assessments are required to limit potential reflections and to avoid risks for public infrastructure or discomfort of residents. The question arises on how to calculate reflections accurately according to the environment's topography. Our approach is founded in a 3D-based simulation methodology to calculate and visualize reflections based on the geometry of the environment of PV systems. This computational model is implemented by an interactive tool for simulation and visualization. Hence, project planners receive flexible assistance for adjusting the parameters of solar panels amid the planning process and in particular before the installation of a PV system

METODOLOGIA de Avaliação Lumínica: Estudo de Caso Estação Antártica Comandante Ferraz

A luz define o que se vê, e esse fenômeno envolve o objeto iluminado, o objeto que ilumina e quem o observa. Na arquitetura, a luz auxilia na percepção dos aspectos formais, conceituais e participa ativamente dos resultados finais, principalmente quanto ao conforto. Especificamente, no que se refere ao usuário e a luz, estão intrínsecas questões fisiológicas e psicológicas assim como o entendimento entre o limiar do conforto e do desconforto humano. Os índices lumínicos propostos e os métodos existentes mensuram normalmente condições padrão de uso e de localização, ou seja, não costumam ponderar a condição de exceção. Situações em que uma pequena quantidade de luz de um ambiente pode ser julgada inadequada nos padrões estabelecidos por normativa, para outras caracterizadas pela reduzida disponibilidade de luz, aquela mínima quantidade existente pode causar um efeito positivo, e não negativo. A pesquisa teve como objetivo geral desenvolver uma metodologia para avaliar a condição de conforto visual para o ambiente Antártico, cuja disponibilidade de luz requer estudos específicos, tendo como estudo de caso a Estação Antártica Comandante Ferraz (EACF). Os resultados obtidos indicam uma nova faixa avaliativa, desenvolvida a partir da Useful Daylight Illuminance (UDI), e o método final apresenta o desempenho lumínico do espaço, através do diagrama de flutuabilidade, medido de duas formas: com um panorama estático, de hora em hora; e dinâmico, com períodos demarcados, concomitantemente. A visualização dos dados compilados nos diagramas permite a avaliação do ambiente e funciona como uma ferramenta ao projetista

Buildings of Tomorrow: Goals and Challenges for Design and Operation of High-Performance Buildings

This reprint aims to address the challenges modern-day buildings face in the context of high energy and resource consumption and climate change. One of the ways to address the issues is holistic design and operation of high-performance buildings in the area of energy efficiency, occupant health, and comfort. All this should be achieved through synergic interconnectedness between parameters such as the indoor–outdoor environment, sustainability, and resilience. Through different chapters, this reprint highlights the key areas, namely, the optimization of building design parameters, the impact of the use of modern-day phase-change materials, the adaptation of occupants and buildings to climate change, the mitigation of urban overheating by cool roofs, and reducing energy demand and CO2 emissions

Towards a GIS-based Multiscale Visibility Assessment Method for Solar Urban Planning

Urban areas are facing a growing deployment of solar photovoltaic and thermal tech-nologies on building envelopes, both on roofs and on façades, essential for the realization of the Swiss Energy Strategy 2050. This process often occurs regardless of the desirable archi-tectural integration quality in a given urban context, which depends on socio-cultural sensitivi-ty and on the visibility of the solar modules from the public space. Visibility and visual impact are recurrent decisional factors in spatial planning processes, with practical implications in-cluding touristic and real estate promotion, outdoor human comfort, way finding, public feeling of security and advertisement. In this thesis, the definition of visibility under a geometrical, physical and psycho-physiological perspective is explored, several quantitative indicators being described and test-ed. The objective is to provide a scale-dependent methodology to assess the visibility of build-ing envelope surfaces exposed to solar radiation, which could host solar modules, in urban areas. A visibility index is determined for inclusion as a variable in a multi criteria method, cover-ing areas from the strategic broad territorial scale to the district level, including neighborhoods and clusters of buildings. Accomplished research includes the estimation of public visual inter-est on the basis of crowd-sourced photographic databases, complementing geometry-based parameters such as cumulative viewsheds and solid angles. At each scale, the visibility index is systematically overlapped on an urban sensitivity layer issued from land use and on a spatial representation of the solar energy generation potential, at an appropriate level of detail. Results indicate that stakeholders can reasonably expect to harvest a serious amount of solar energy by means of building integrated solar systems without crucially affecting public perception. In the study area located in the city of Geneva (Switzerland), more than 50 m2 / building of non-visible envelope surface receiving sufficient solar radiation for an economically viable solar re-furbishment is available over half of the buildings. Solar thermal collectors or PV panels in-stalled on scarcely visible surfaces, mainly situated in courtyards, far from the streets or in deep urban canyons, could cover about 10% of the annual heating demand or alternatively, the same share of electricity needs on a district basis. At the same time, plenty of highly visible areas remain available for high-end solar deployments, which could also serve pilot and demonstration purposes

Urban planning support based on the photovoltaic potential of buildings: a multi-scenario ranking system

An increased use of renewable energy and of energy efficiency measures in buildings is needed to face the urgency of climate change. Buildings are in fact among the highest worldwide consumers of primary energy, mostly of fossil fuel origin, while still making insufficient use of in-situ renewable energy sources. To find a solution to this situation, many municipalities have promoted the use of solar cadastres mapping the solar energy potential of the existing building stock. However, their implementation has limits from different points of view including assessment accuracy, representation methods, and decision-support. To overcome these limits, this thesis proposes a planning-support system based on the photovoltaic (PV) potential of buildings. The goal is to provide decision-makers and stakeholders with a robust method to assess the potential of photovoltaic electricity generation of existing buildings under uncertain environmental conditions. The developed methodology is based on an urban-scale modeling workflow that includes the simulation of the photovoltaic electricity production and a simplified estimation of the building energy retrofit potential. Existing state-of-the-art models for solar radiation, building energy and PV performance are coupled in the workflow, which relies on a vector 3D city model featuring an accurate representation of buildings, terrain, and vegetation. The proposed modeling workflow also includes an innovative approach for simulating the arrangement of PV modules on the building envelope, which influences both the energy yield and the acceptability of the system. The modeling workflow is in turn integrated into a planning-support system that provides a robust assessment of the photovoltaic potential through risk-averse scenarios. We consider here two crucial yet underestimated uncertainty factors: weather and vegetation. The results are aggregated at different scales and, for each scale, the spatial locations are ranked through pairwise comparisons according to relevant energy indicators. The results are finally displayed in a 3D-mapping tool featuring false-color overlays at the considered aggregation scales to address different objectives and inform decision-makers. We conducted sensitivity analyses towards different input data resolutions and modeling scenarios so as to achieve a good trade-off between accuracy and computational cost and define confidence intervals for the calculated values. The simulated PV yield was also compared against measured data from an existing PV installation. The proposed modeling workflow and planning-support system were tested in an urban district within the city of Neuchâtel (Switzerland). The analysis highlighted areas with the highest potential and provided a priority list of interventions. It also showed the impact of vegetation on absolute results and especially on the ranking of the spatial locations evaluated by their energy potential