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Linear Fresnel reflectors are a versatile solar concentration technology, suitable for a wide range of industrial processes and thermal conditioning applications. Such collectors entail a certain footprint, generating shading on the surface where they are installed. This effect is rarely quantified but may play an indirect role on the surface below. When installed on a roof, the solar radiation heats the building less. In places where the annual heating demand is higher than the cooling demand, this constitutes an asset. However, this becomes a disadvantage when the cooling demand is higher annually than the heating demand. Essentially, the reduced solar radiation allows for the growth of plants that would not grow without the shade provided by the collector. The present paper is a quantitative analysis of such shading based on the linear Fresnel reflector of the Cyprus Institute. The work was conducted using the Tonatiuh++ ray-tracing software to determine the annual radiation blocking. A total of four years of actual meteorological measurements were applied directly to the ray-tracing model. [ABSTRACT FROM AUTHOR]

The increase in renewable energy sources (RESs) in distribution grids is a major driver for achieving green energy goals worldwide. However, RES power inverters affect power quality, increase power losses, and, in certain cases, may cause power interruptions due to harmonics, deterioration of the rate of change of frequency, and inability to rapidly react in grid faults. Today, phasor measurement units (PMUs) are the ultimate tools for real-time monitoring of distribution grids' health, and they enable several data-driven added-value services such as fast and automated fault detection, isolation, and recovery; state estimation; power quality monitoring; dynamic events analysis, etc. The present paper proposes an open hardware and software PMU platform, which is low cost, high performance, expandable, and, in general, suitable for research and innovation activities. The system is based on two processor modules (a digital signal processor from Texas Instruments TMS320c5517, and a microprocessor System-in-Package from Octavo Systems OSD3358), two local databases of 64 Gbytes each, GPS module, 5G modem interface, as well as analog and signal conditioning circuits to interface three-phase power voltage and current signals. The entire hardware design, schematics, and instrumentation components, as well as all firmware and software functions are completely open source. Pilot operation of the prototype design has been installed in three medium-/low-voltage substations in Cyprus, as well as twelve substations in Spain and Italy. [ABSTRACT FROM AUTHOR]

The high penetration of the Renewable Energy Sources and other emerging technologies likely to be installed in future power grids will pose new operational challenges to grid operators. One of the main issues expected to affect the operation of the power grid is the impact of inverter-based technologies to the power system inertia and, hence, to system stability. Consequently, the main challenge of the future grid is the evaluation of the frequency stability in the presence of inverter-based systems and how the aforementioned technology can support frequency stability without the help of the rotating masses of the traditional power grid systems. To assess the above problem, this paper proposes a methodology to evaluate the frequency stability in a projection of the real distribution grid in Cyprus with the time horizon to be the year 2030. The power grid under investigation is evaluated with and without the presence of smart hierarchical controllers for providing support to the power system under disturbance conditions. The advanced controllers were applied to manage the available power resource in a fast and effective manner to maintain frequency within nominal levels. The controllers have been implemented in two hierarchical levels revealing useful responses for managing low-inertia networks. The first is set to act locally within a preselected area and the second level effectively supporting the different areas for optimal operation. After undertaking a significant number of simulations for time-series of one year, it was concluded from the results that the local control approach manages to minimize the frequency excursion effectively and influence all related attributes including the rate of change of frequency (RoCoF), frequency nadir and frequency zenith. [ABSTRACT FROM AUTHOR]

In response to escalating environmental challenges, this research underscores the pivotal role of sustainable construction practices, particularly focusing on bioclimatic design as a foundational element within the realm of sustainable architecture and environmental upgrading of buildings, within the broader context of sustainable urban planning. The study delves into the perspectives of residents in Cyprus concerning bioclimatic building design. Employing a quantitative methodology, the investigation aims to comprehensively assess homeowner views on the benefits, motivations, concerns, and preferred techniques associated with bioclimatic design. By comprehending these perspectives and contextual factors, this study identifies obstacles hindering broader implementation and illuminates why adoption remains limited, despite the potential for substantial energy and emissions reductions. The research also examines the background of respondents, such as heating/cooling systems, energy expenses, and upgrade preferences, to provide essential context for the findings. A structured questionnaire was administered to a stratified sample of 150 pedestrians in the Pafos area, ensuring a representative cross-section of the local population. This method allowed for a robust examination of demographic influences on opinions and an in-depth analysis of the impact of residential characteristics. The findings reveal a substantial influence of cost considerations in shaping decisions related to residential property development and the renovation of existing structures, contributing to the limitation of widespread adoption across the island. This influence persists even as a majority of respondents express a readiness to undertake building energy upgrades, among which, the most popular actions include the installation of specialized glass, the replacement of traditional air conditioning units with inverters, and the adoption of energy-efficient lighting. The research culminates in the proposal that introducing financial incentives has the potential to enhance homeowner participation in bioclimatic and energy upgrades. This recommendation is particularly salient in the climatic context of Cyprus, where the implementation of solar control measures emerges as a promising avenue for bolstering energy efficiency. In considering the socio-economic dimensions implicit in these findings, it becomes evident that the interplay between financial considerations and sustainable construction practices is a critical aspect. The identified barriers underscore the necessity for nuanced strategies and policy frameworks that address the socio-economic dimensions of bioclimatic design adoption. In this context, the study contributes to the existing body of knowledge by shedding light on the intricate relationship between financial factors and sustainable architectural practices, offering implications for future research endeavors and potential avenues for policy interventions. [ABSTRACT FROM AUTHOR]

Growing concerns over environmental issues and sustainable living have resulted in increased interest in renewable energy and energy efficiency. The real estate market is no exception, with homeowners increasingly considering the market value of green and sustainable buildings, which can offer both energy efficiency and potential health benefits. This study investigates the level of interest among homeowners in investing in renewable energy sources and energy efficiency measures for their homes and how it relates to their perception of the market value of green or sustainable buildings in the real estate market. A survey was conducted in the Paphos urban complex in Cyprus, with 180 participants over the age of 18. The participants were selected through a random sampling method and were representative of the general population in terms of gender, age, and income. Data were collected on their attitudes towards renewable energy sources and energy efficiency, as well as their perceptions of the market value of green buildings. The data collected were analyzed using various statistical methods, including Cronbach's α coefficient, the non-parametric Friedman test, descriptive statistics, and factor analysis, with the Statistical Package for the Social Sciences (SPSS) being used for coding and analysis. Results indicate that 64% of the homeowners surveyed were interested in investing in renewable energy sources, and 72% were interested in energy efficiency measures. Additionally, findings suggest a moderate level of interest (58%) among homeowners in investing in renewable energy sources and that this is positively associated with their perception of the market value of green buildings. Furthermore, homeowners with higher income and education levels tend to be more interested in investing in renewable energy sources and energy efficiency measures and perceive green buildings as having higher market value. This study provides insights into the factors that drive homeowners' investment in renewable energy sources and energy efficiency measures, shedding light on the relationship between homeowners' perceptions of the market value of green buildings and their interest in such investments. [ABSTRACT FROM AUTHOR]

One of the most effective strategies to mitigate water shortages worldwide is to reuse treated wastewater for freshwater production employing reverse osmosis (RO) technology. This strategy is appropriate in urban areas of arid or semi-arid regions as it can provide a sustainable and reliable water source close to the consumers. One of the drawbacks of RO is the high variability of production costs due to the electricity intensity. In addition, depending on the electricity source, it can also result in substantial environmental costs. This study showed that upgrading pumping and RO membrane systems of a wastewater reuse plant in Cyprus can significantly alleviate these drawbacks in terms cost, water recovery rate, and air pollution. The water-recovery rate of the upgraded RO plant increased from 43.2 to 75 percent, which resulted in a substantial net financial benefit due to the reduction in the quantity of wastewater purchased and the increase in potable water produced. The upgraded system also reduced the electricity requirement from 3.63 kWh/m3 to 1.92 kWh/m3. Pollution emissions decreased substantially because of the reduction in electricity requirements. The beneficiaries of these lower emission costs are the residents of Cyprus and global society. Overall, the benefit of upgrading the plant is highly attractive with more than 65 percent annual real internal rates of return in financial and economic terms. Positive net present values are realized for all the scenarios considered. [ABSTRACT FROM AUTHOR]

The modelling of Linear Fresnel Collectors (LFCs) is crucial in order to predict accurate performance for annual yields and to define proper commands to design the suitable controller. The ISO 9806 modelling, applied to thermal collectors, presents some gaps especially with concentration collectors including LFCs notably due to the factorisation of the incidence angle modifiers and the fact that they are considered symmetric around the south meridian. The present work details the use of two alternative modellings methodologies based on recorded experimental data on the solar system installed at the Cyprus Institute, in the outskirts of Nicosia, Cyprus. The first modelling is the RealTrackEff, which is an improved ISO9806 modelling, and the second is constructed using the CARNOT blockset in MATLAB/Simulink. Both models include all the elements of the heat transfer fluid loop, i.e., mineral oil, with a tank and a heat-exchanger. First, the open loop's studies demonstrated that the root mean square on temperature is 1 °C with the RealTrackEff; 2.9 °C with the CARNOT and 6.3 °C with the ISO9806 in comparison to the experimental data. Then, a PID control is applied on the experimental values in order to estimate the impact on the outlet temperature on the absorber and on power generation. Results showed that the error on the estimation of the heat absorbed reaches 32%. [ABSTRACT FROM AUTHOR]

An innovative thermal energy storage system (TESSe2b) was retrofitted in a residential building in Cyprus with a typical Mediterranean climate. The system comprises flat-plate solar collectors, thermal energy storage tanks filled with organic phase change material, a geothermal installation consisting of borehole heat exchangers with and without phase change material and a ground source heat pump, an advanced self-learning control system, backup devices and several other auxiliary components. The thermal energy storage tanks cover the building's needs at certain temperature ranges (10–17 °C for cooling, 38–45 °C for heating and 50–60 °C for domestic hot water). A performance evaluation was conducted by comparing the TESSe2b system with the existing conventional heating and cooling system. The systems were simulated using commercial software, and the performance of the systems and the building's energy needs were calculated. Based on the energy quantities, an economic analysis followed. The equivalent annual primary energy consumption with the conventional system resulted in being 43335 kWh, while for the storage system, it was only 8398 kWh. The payback period for the storage system was calculated to be equal to 9.76 years. The operation of the installed storage system provided data for calculations of the seasonal performance factor and storage performance. The seasonal performance factor values were very high during June, July and August, since the TESSe2b system works very efficiently in cooling mode due to the very high temperatures that dominate in Cyprus. The measured stored thermal energy for cooling, heating and domestic hot water resulted in being 14.5, 21.9 and 6.2 kWh, respectively. Moreover, the total volume of the phase change material thermal energy storage tanks for heating and domestic hot water was calculated to be roughly several times smaller than the volume of a tank with water as a storage medium. [ABSTRACT FROM AUTHOR]

Shallow Geothermal Energy Systems (SGESs) constitute Renewable Energy Systems (RES), which find application in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are associated with Ground Heat Exchangers (GHEs), whereby heat is gained/lost through a network of tubes into the ground. GSHPs have failed to flourish in the RES market due to their high initial costs and long payback periods. In this study, the use of Energy Geo-Structure (EGS) systems, namely, the foundation (or energy) piles and the foundation bed of a residential building in Cyprus, was computationally modeled in the COMSOL Multiphysics software. First, the single-houses' trend in number of units and area in Cyprus was examined and a theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was considered. The heating and cooling loads were estimated in the TRNSYS software environment and used as inputs to investigate the performance of the GSHP/GHE systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for residential building integration. Next, the systems were economically evaluated through a comparison with a convectional Air Source Heat Pump (ASHP) system. The economic analysis showed that the cost of the suggested conversions of the foundation elements into GHEs had short payback periods. Consequently, either using the foundation piles or bed as a GHE is a profitable investment and an alternative to conventional RES. [ABSTRACT FROM AUTHOR]

Three load matching indicators (self-consumption rate, self-sufficiency rate, loss of load probability) and the CO2 emissions were evaluated for 55 Cypriot households with 3 kWp rooftop photovoltaic (PV) generators. The calculations were performed using 30-minute generation and consumption data from a large scale smart meter project in Cyprus. To investigate the effects of recent advances in local legislation, an analysis for higher PV capacities (5 kWp and 10 kWp) was also performed. The PV generation profiles for 5 kWp and 10 kWp PVs were obtained by scaling the 3 kWp PV generation profiles. The results showed that the self-consumption of the analyzed households varied seasonally, as it was related to their heating and cooling demand. More interestingly, the ratio between the households' annual electricity generation and demand, formally defined here as generation-to-demand ratio (GTDR), was found to be related to the value ranges of the studied load matching indicators. Hence, on average, households with 3 kWp PV generators annually self-consumed 48.17% and exported 2,415.10 kWh of their PV generation. On the other hand, households with larger PV generators were characterized by a higher GTDR, but lower load matching capabilities. For the cases of 5 kWp and 10 kWp PV generators, the average self-consumption fell to 34.05% and 19.31%, while the exported PV generation was equal to 5,122.47 kWh, and 12,534.90 kWh, respectively. Along with lower load matching capabilities, households that generated more than they consumed were also found to have a lower potential for CO2 emissions reduction per installed kWp within the boundaries of the building. In this context, the GTDR could be used by stakeholders to characterize buildings, infer possible value ranges of more complex indicators and make evidence based decisions on policy and legislation. [ABSTRACT FROM AUTHOR]