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• The influences of the geometric parameters of the reactor on the SCPP-HPCR are investigated. • A formula is proposed to calculate the CO 2 emissions reduction of the system. • The optimal operating conditions of the SCPP-HPCR is analyzed. • 2.38 kg of CH 4 is degraded and 375.52 kg of CO 2 is reduced through the system one day. The increase of 1.09 °C in global temperature resulted in significant catastrophes because of the extreme climate. The climate change rate can be slowed down by reducing the levels of CH 4 and CO 2 in the atmosphere. The solar chimney power plant integrated with a honeycomb photocatalytic reactor (SCPP-HPCR) uses the photocatalytic technology to remove atmospheric CH 4. In addition, CO 2 emissions can be reduced from coal fired power plant due to the generating capacity of the system. In this paper, the influence of the geometric parameters of the reactor and turbine on the overall performance of the SCPP-HPCR is studied by numerical simulation. The obtained results showed that the flow resistance inside the system was mostly caused by the HPCR at low turbine speed, and primarily by the turbine at high turbine speed. Reducing the pore diameter of the reactor could improve the photocatalytic performance of the SCPP-HPCR more than increasing the turbine speed. The SCPP-HPCR having a pore diameter of 3 mm, porosity of 0.85, and constant turbine speed of 180 rpm, built in Qianyanzhou, China, could remove 2.38 kg of CH 4 and reduce 375.52 kg of CO 2 in one day. [ABSTRACT FROM AUTHOR]

• Physical models to design the PV/T air systems are presented. • Electrical and thermal models are outlined to perform the performances of PV/T air-based systems. • An experimental validation of the discussed models is assessed in terms of thermal and electrical efficiencies. Solar photovoltaic thermal (PV/T) systems have the capacity to become a key actor in the world's energy transition. The design of such systems requires the implementation and development of physical models, which can predict their thermal and electrical performances. In this paper, some of the main models for designing PV/T systems are developed. In fact, various configurations of equivalent-circuit models are presented to perform the electrical behavior of PV/T systems. Further, a Quasi-Steady Thermal Model (QSTM) is developed to forecast thermal performances. All reported models are validated based on the literature results. The efficiency analysis of developed models demonstrates that the good choice of equivalent-circuit model is substantial and varies according to the climatic changes. Limitations of certain electrical models have also been outlined and discussed. This work could be a guideline to researchers for the physical modelling of PV/T systems. [ABSTRACT FROM AUTHOR]

• The review on performance impact of different design components of PVT modules. • The electrical and thermal efficiency analysis from various researches work on PVT modules. • The performance capacity results of different PVT structures has been reviewed and presented. • Recommendations were drawn for future performance enhancement. The Photovoltaic/Thermal (PVT) technology has attracted many researchers and scholars in order to increase the level of renewable energy utilization minimizing the issues caused by climate change especially the global warming which has the main roots on the greenhouse emissions produced by nonrenewable energy utilization. A PVT module is a combination of photovoltaic (PV) technology and solar thermal (ST) technology that receives and converts solar radiation into electrical and thermal energy at the same time leaving less greenhouse emissions. Even though the PVT technology seems simple in some designs and has low utilization cost, the inadequate performance and initial costs of PVT modules can slowdown their market. Based on research work outcomes and analysis, the design components of PVT modules have a strong influence on the performance. Analyzing the performance impacts of different main components of PVT module is very important not only for researchers but also for manufacturers because it points out both weaknesses and strengths for further improvements and invention of the technology to meet the market requirements. In this paper we deeply investigated the performance of PVT modules and the performance influence of each of the main components of PVT module by making a comprehensive review, finding analysis, summarizing and presenting the outcomes. [ABSTRACT FROM AUTHOR]

• The Shockley-Queisser model is extended to account for all of the spectral energy. • Thermodynamic losses are described and cell temperature is accounted for. • Real spectra can be analyzed, accounting for geographical and climatic variation. Research into the fundamental limitations to photovoltaic power conversion has historically used a single predetermined set of conditions to define device performance limitations. This fails to account for the many variables involved in real-world situations. Previous work describing thermodynamic losses in solar energy conversion has typically used an analytical approach, precluding the use of real-world spectra. This paper describes a model which marries the advantages of the analytical approach with a numerical detailed balance calculation, enabling analysis of maximum attainable power conversion efficiency and associated loss mechanisms in photovoltaics under more representative conditions. Input spectra in the model are treated as separate beam and diffuse components, both in terms of power and subtended angle. Differences in conversion show that diffuse light is effectively under maximum concentration. This does not result in an efficiency gain since the equivalent energy is instead accounted for in the Carnot loss. The Carnot limit for the diffuse portion of the spectrum is therefore lower than that for direct light. Simulated hourly "clear sky" spectra across a year were analysed for five geographically disparate locations. Results showed that at higher latitudes narrower band gap devices have a similar maximum efficiency to those with wider band gaps, whilst at lower latitudes wider band gap devices have a slightly higher maximum efficiency. This is compounded by increased irradiance at lower latitudes. Irrespective of band gap, annual energy conversion shows little variation at lower latitudes, with greater conversion in summer being offset by reductions in winter at higher latitudes. [ABSTRACT FROM AUTHOR]

The present paper discusses issues related to the three major problems of the built environment in Europe and in particular, the energy consumption of buildings, the energy poverty and the local climate change. The article introduces the idea of a zero concept world where the global impact of the three specific sectors will be diminished. The paper analyses the actual status of each sector and identifies the main problems. It discusses and sets a road map to satisfy this objective, involving future quantitative and qualitative targets for the three considered sectors while it investigates the major technological, economic and social forces and policies that have to be employed in order to minimize the energy consumption of buildings, eradicate the energy poverty and mitigate the local climate change. The links, synergies and impacts between them are analysed in a comprehensive way and the interrelated nature and characteristics of the three sectors is highlighted. The mechanisms to transform the actual problems into opportunities and appropriate drivers for future development are identified and analysed. A road map involving a full estimation of the necessary investments to fulfil the defined targets is presented. The major medium and long term benefits for the society, including the impact on the economy, employment, the environment and health are fully quantified and analysed. [ABSTRACT FROM AUTHOR]

• Quantitative assessment of the heat waves in different city zones. • Quantification of the heat waves impact on building energy performance. • Influence of heat waves on the indoor operative temperature. • Impact of the synergic effect of heat waves and urban heat island. Global and local climate change increases the occurrence and the magnitude of extreme phenomena, as urban heat island and heat waves. These phenomena seriously affect the quality of life in several aspects: society, health, environment; they also heavily affect the building sector, increasing the energy use for cooling and deteriorating the indoor thermal environment. This paper utilizes data from a continuous urban microclimatic monitoring over three years to quantify the impact of heat waves on the thermal quality of two reference residential buildings in the city of Rome, Italy. The synergic effect of heat waves with the urban heat island is also analysed. The observation period includes summers of 2015, 2016 and 2017. The buildings' response is analysed through numerical thermal analyses in transient regime, taking into account several variants: thermal insulation, mechanical cooling system and thermal free-floating conditions, with different night ventilation strategies. Results show that daily average temperature and urban heat island intensity increase by up to 4.3 °C and 1.5 °C respectively during the heat waves with respect to the rest of the summer. The building cooling energy use rises up 87% during heat wave periods, while average operative temperature in free-running buildings increments by up to 3.5 °C. Results also show the impressive combined impact of heat wave and heat island: triplication of cooling energy use in the worst case and increase of the average operative temperature above 5 °C. [ABSTRACT FROM AUTHOR]

• The performances of single and double diode equivalent circuit models are discussed. • A new approach that combines both the single and double diode models is proposed. • The proposed hybrid approach is tested under climate variation of real field data. Various works investigated different photovoltaic (PV) cell equivalent-circuit models and several techniques were proposed to extract their unknown parameters. The present paper analyzes the current/voltage (I-V) characteristics for Si-crystalline PV modules under non-standard conditions of irradiance and temperature, by using single-diode and double-diode models. The Chaibi and Ishaque methods are employed to determine the parameters for each equivalent-circuit model. Then, the I-V curves provided by the manufacturers and the calculated I-V characteristics are compared at different levels of irradiance and temperature. The comparison suggests prioritizing one of the two equivalent-circuit models according to the prevailing meteorological inputs. As such, a hybrid approach is proposed in order to select the most appropriate model depending on the relevant climatic conditions. The presented approach accuracy is evaluated using real weather data of two PV plants located in two different climatic zones (Mediterranean and Semi-Continental). Results show that the double-diode model is more reliable for low-irradiance levels; however, the single-diode model performs well with low-temperature fluctuations. An error reduction of 53.93% and 21.04% can be reached for the cloudy weather and for the sunny days, respectively. Accordingly, this approach can be easily implemented as a computing tool to achieve more accurate prediction in the PV systems simulations. [ABSTRACT FROM AUTHOR]

• Evidence syntheses for sustainable urban development are of increasing importance. • An evidence map of systematic reviews and meta-analyses on this topic is presented. • The map contains 131 reviews examining numerous aspects of built environment. • The paper is supplemented by a free online database and interactive visual summaries. Sharing of key evidence on strategies for reducing resources consumption and lowering carbon footprint is essential to alleviating risks of increasing urbanization, population growth and looming climate change impacts. However, finding scientifically robust research and distilling knowledge to draw confident conclusions in a reasonable timeframe is challenging due to the sheer volume of rapidly accumulating research evidence. Primary evidence is aggregated in secondary studies, i.e. various types of reviews, including systematic reviews and meta-analyses. However, the number of secondary studies is also growing rapidly and their quality varies. This work presents the first systematic review of secondary studies which were claimed to be systematic reviews or meta-analyses of literature relevant to reducing carbon footprint of the built environment or its co-benefits (e.g., health and well-being). The resulting searchable and updatable database contains 131 reviews published between 2001 and early 2018. Importantly, the quality of the included reviews was assessed and categorized. The database is available via a dedicated website which includes interactive visualizations and filtering tools. In its current form, the interactive map and database can help discovery and appraisal of secondary evidence for decision-making and research use, supporting transition to low carbon future. This overview aimed to reveal trends and patterns, including gaps, in the publications of research syntheses relevant to sustainable built environment. The results showed that the number of reviews claiming to by systematic reviews or meta-analyses is rapidly increasing in recent years. However, the exact methodology used and the standard of adherence to methodological and reporting guidelines varies widely among reviews. The included reviews span different disciplines, such as environmental sciences, engineering, urban planning, public health, and social sciences. The first authors from USA, UK and Australia contributed the most relevant reviews. Health and well-being, along with closely related environment and nature, are currently the best synthesized subject areas, while there are still very few included reviews related to policy, economy or information technology, indicating synthesis gaps in these areas. Our analysis reveals the lack of standardized definitions of different types of research syntheses across disciplines, as well as poor reporting quality of research syntheses. We encourage detailed descriptions of methods, providing datasets and interactive visualizations as integral components of the future systematic reviews and evidence maps. [ABSTRACT FROM AUTHOR]

• Model development on the lifetime energy prediction and annual energy assessment. • Expression of domestic PV generation potential in various climatic conditions. • Demonstration of the importance of the reliability and maintenance of PV systems. • Demonstration of the energy prediction risks regarding PV systems' economic viability. This paper presents a generic model for the prediction of the lifetime energy production of photovoltaic (PV) systems and the assessment of their annual energy yield in different time periods of operation. As case studies, it considers domestic PV system generation potentials in the UK and India to demonstrate the model results across a range of contrasting climatic and operating conditions. The model combines long-term averages of solar data, a commercial PV system simulation package and a probability density function to express the range of the annual energy prediction in different time periods of system operation. Moreover, a sensitivity analysis based on degradation rates and energy output uncertainties is embedded in the lifetime energy calculations. The importance of the reliability and maintenance of the PV systems and the energy prediction risks, especially regarding economic viability, are demonstrated through the PV lifetime energy potentials in these two countries. It is shown that, even for countries that are significantly different in respect to their solar resource, PV systems may produce similar amounts of energy during their lifetime for reasonable assumptions of degradation rates and uncertainty levels. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper is to examine the energy consumption of and determine energy-efficient design strategies for mid-rise and high-rise office buildings in composite climate. For this purpose, a comparative study is performed of six energy-efficient office buildings in composite climate in India. The selected energy-efficient office buildings are situated in the major cities (Delhi, Gurgaon, and Hyderabad) of India with a composite climate. This study investigates the effectiveness of different design strategies for reducing the heating, ventilation, and air-conditioning (HVAC) and lighting loads of the six buildings. The effect of factors such as the building form, envelope configuration, placement of the service core, window-to-wall ratio (WWR), and percentage of air-conditioned space on the HVAC load are analyzed. Similarly, the effect of the plan depth and WWR on the lighting load is also determined. Finally, the findings of the study are used to recommend effective design strategies for high-rise office buildings in composite climate. Moreover, the energy performance data are compared with the national energy consumption benchmarks for composite climate. The comparison indicates the design strategies performed well, that lead to a decrease in the energy consumption of high-rise office buildings in composite climate. [ABSTRACT FROM AUTHOR]

Facing the climate change is a common priority, due to ethical issues related to general concept of sustainability and livable future for the next generations. Moreover, ethical aims for contrasting energy poverty, heat-related diseases and deaths, availability of food and water, infections and viral-bacteriological risks, meteorological extreme phenomena, such as floods and intense and destructive precipitations, are stringent and pressing targets. All serious and independent investigations reveal future scenarios of an overall global warming that surely make worrying the evolution of quality of life on this earth. Each one has to do his part. In this study, the research is focused on renewable technologies for the passive cooling of buildings. Indeed, the space cooling is a strongly increasing use of energy and induces a vicious circle, being, at the same time, a cause and an effect of the anthropogenic overheating of the planet. The paper mainly reviews techniques for suitably governing the energy interaction between buildings and surrounding environment. The energy efficiency concerns the building envelope design, the use of efficient HVAC systems, adoption of renewable energy on-site. On the other hand, every energy conversion process determines waste heat, so that also a ‘free of operational cost’ solar cooling system however causes dissipation of heat into the ambient. Finally, renewables cannot be the unique solutions for supplying the energy required for the building use. Conversely, strategies for reducing the building cooling are needed, and these are reviewed in this study. In thermodynamics terms, the building is seen as part of the system and not the mere control volume. Greenery of facades and roofs, phase change materials, nocturnal convective cooling, evaporative and ground cooling, solar systems such as chimneys for improving the building ventilation are here discussed, as well as emerging technologies such as breathing walls and dynamic insulation. The reviewed studies, selected on the basis of more recent progresses concerning the investigated technologies, revealed potentialities but also criticalities in the design. [ABSTRACT FROM AUTHOR]

The present paper introduces the concept of solar cooling as a major issue in the valorization of the solar source in front of the challenge represented by the worldwide growing demand of cold. The most relevant solar cooling technologies are briefly discussed as well as their possible combination and implementation in different contexts. Some real-world installations are proposed as representative of possible plant design in a variety of climate and building integration conditions. Through these cases, trends of innovation are identified both for small and settlement scale applications, supporting the perspective of a more efficient exploitation of the solar cooling potential. [ABSTRACT FROM AUTHOR]

Local and global climate change increases the ambient temperature of cities by several degrees with important consequences on energy consumption, health and the economy. Advanced urban mitigation technologies contribute to decrease the ambient temperature and counterbalance the impact of urban heat islands. The present paper analyses and presents in a comparative way the mitigation potential of the known mitigation technologies using performance data from about 220 real scale urban rehabilitation projects. The average and peak temperature drop of reflective technologies, greenery, evaporative systems, earth to air heat exchangers and their combinations is calculated and presented. The mitigation potential of the main systems like cool roofs, cool pavements, green roofs, urban trees, pools and ponds, sprinklers, fountains, and evaporative towers, is analysed. It is found that the potential of the main mitigation technologies is considerable and can counterbalance UHI effects partly or fully. The average peak temperature drop calculated for all projects is close to 2 K, while the corresponding decrease of the average ambient temperature is close to 0.74 K. Almost 31% of the analysed projects resulted in a peak temperature drop below 1 K, 62% below 2 K, 82% below 3 K and 90% below 4 K. [ABSTRACT FROM AUTHOR]

Urban systems, from their early origins, were acknowledged to be responsible for both benefits and penalties due to anthropogenic actions affecting human wellbeing. In this view, local overheating exacerbated by urban heat island phenomenon has been identified as a result of anthropogenic actions responsible for citizens’ health issues and other serious socio-economic consequences in urban areas, where almost the 70% of the world population is expected to live in thirty years. This fact imposes to respond to an urgent research question concerning the development and the real-world application of effective mitigation strategies against urban climate change phenomena, for a better population resilience. Among the variety of these strategies, the implementation of “cool” coatings over urban surfaces exposed to the solar radiation, i.e. cool roofs and cool pavements, represents a proved solution to counteract such overheating effect and its negative consequences on the population living in urban context. In this view, the present work reviews the state of the art about the development of new materials and their main applications as cool roofing and paving systems for passive cooling purpose of buildings and cities, which have been published in more than 260 papers in the last decades. Both indoor and outdoor passive cooling benefits were clearly demonstrated and quantified with varying climate conditions, material characteristics and the built environment context. Despite that, the investigation around this issue is still active worldwide, from chemistry, material science and engineering fields. Additionally, new triggers were highlighted as possible starting points for future scientific focus. In particular, still active discussions give rise to promising research findings expected to clarify (i) the effect of cool coatings on pedestrians’ glare, possibly mitigated by directionally-reflective materials, (ii) the role of cool coatings for HVAC optimization, (iii) the combined benefits of cool coatings and thermal-energy storage techniques for UHI mitigation. [ABSTRACT FROM AUTHOR]

This paper investigates the relationship between two parameters characterizing a given location on a given day: the daily clear sky index KT ∗ and the intraday variability given by the standard deviation of the changes in the hourly clear sky index σ ( Δ kt Δ t ∗ ) . Empirical evidence assembled from twenty climatically distinct locations led us to derive a simple model to infer intraday variability from the day’s clear sky index. Although the model shows little dependence on location, we did observe a systematic difference traceable to a location’s prevailing cloud formation regime. Therefore, we also propose two alternative models for sites where cloud formations is influenced by local orography and sites where cloud formation is traceable to weather events only. Finally, we present a possible application of the models to enhance the informative content of day(s) ahead NWP forecasts. [ABSTRACT FROM AUTHOR]

Vernacular buildings in Egypt express a variety of passive low-tech approaches in design and construction to achieve human comfort and fulfil inhabitants’ requirements. They have been devised to suit living in regions where local inhabitants had to invent various passive building strategies to live under severe local climatic conditions without depending on fossil fuels. This paper discusses a retrofitting approach for off-grid vernacular buildings in the Western Desert of Egypt. The study hypothesis argues that, when retrofitted and equipped with renewable energy solutions, vernacular structures can act as nearly zero energy buildings. A post occupancy evaluation was used as an assessment tool for two pilot projects that served as case studies. Results showed that combining vernacular passive strategies with affordable active renewables such as roof top solar panels results in a hybrid energy efficient retrofitting solution for deprived off-grid vernacular buildings. The intention is for the results to act as a basis for future retrofitting that would take into account the challenges and obstacles inherent in such work. This is an aim capable of contributing to a reduction of energy consumption that would also encourage retrofitting using renewable solutions for existing housing stock in Egypt. [ABSTRACT FROM AUTHOR]

The hot-spot phenomenon is a relatively frequent problem occurring in current photovoltaic generators. It entails both a risk for the photovoltaic module’s lifetime and a decrease in its operational efficiency. Nevertheless, there is still a lack of widely accepted procedures for dealing with them in practice. This paper presents the IES–UPM observations on 200 affected photovoltaic modules. Visual and infrared inspection, as well as electroluminescence, peak power rating and operating voltage tests have been carried out. Thermography under steady state conditions and photovoltaic module operating voltage, both at normal photovoltaic system operating conditions, are the selected methods to deal in practice with hot-spots. The temperature difference between the hot-spot and its surroundings, and the operating voltage differences between affected and non-affected photovoltaic modules are the base for establishing defective criteria, at the lights of both lifetime and operating efficiency considerations. Hot-spots temperature gradients larger than 20 °C, in any case, and larger than 10 °C when, at the same time, voltage operating losses are larger than the allowable power losses fixed at the photovoltaic module warranties, are proposed as rejecting conditions for routine inspections under contractual frameworks. The upper threshold of 20 °C is deduced for temperate climates from the basic criterion of keeping absolute hot-spot temperatures below 20 °C. [ABSTRACT FROM AUTHOR]

This paper deals with the detailed analysis of evacuated tubular collector (ETC) connected in series in the terms of thermal energy and exergy gain. The study have been done by considering four type of weather conditions (a, b, c and d type) for the climatic condition of New Delhi, India. The maximum outlet temperature increases from 53.91 °C to 129.23 °C and the useful daily thermal gain increases from 3.29 kW h to 6.34 kW h for as the number of collector increases from two to six, at constant mass flow rate ( m ̇ f ) = 0.002 kg/s. For a mass flow rate ( m ̇ f ) = 0.002 kg/s, the temperature difference between inlet and outlet ( Δ T ) increases (55.52–133.29 °C) as the number of collector increases from 2 to 12 and then becomes almost constant. Monthly gain in thermal energy and exergy are also evaluated by considering four number of collectors connected in series and at constant mass flow rate of 0.002 kg/s. The characteristic equations of ETC have also been developed. Instantaneous thermal efficiency decreases from 53.5% to 34.4% as the number of ETC increases from two to six. [ABSTRACT FROM AUTHOR]

In this paper, the Performance analysis in terms of effect of carbon credit earned on annualized uniform cost of glazed hybrid photovoltaic thermal air collector on the basis of annual thermal energy and exergy have been analyzed for New Delhi climatic conditions. The effect of interest rates on annualized uniform cost has also been evaluated. For the lifetime (30 year) analysis, the carbon emission reduction comes to Rs 109,242 and Rs 25275.6 on the basis of overall thermal energy and exergy basis. It has also been observed that there is significant decrease in annualized uniform cost due to carbon credit earned. [ABSTRACT FROM AUTHOR]

In this paper the water uptake by PV-modules during weathering tests of the type approval standard IEC 61215 was simulated and compared with the water ingress under ambient outdoor conditions. For this purpose, the base materials, one encapsulant (EVA) and one back sheet (TPT), were analyzed regarding their water vapor permeability. The micro climate a PV-module sees at its surface was monitored during accelerated IEC tests and at outdoor test sites located in four different climatic regions. These measured values were used for FEM based simulations of the water ingress into PV-modules. The results show the speed and the amount of water uptake under IEC-test conditions as damp heat, humidity freeze and thermal cycling tests compared with the water ingress under the different climates. It can be stated that the IEC-damp-heat test provokes almost two times higher water concentrations in the encapsulant between cell and glass than outdoor weathering can adjust over 20 years. The humidity freeze test shows a similar behavior and even the thermal cycling test results in a slightly water uptake in the back sheet. [ABSTRACT FROM AUTHOR]

Solar irradiation calculations depend on atmospheric variations and sunshine duration record interval. Generally, it is calculated by using the classical Angström–Prescott equation, which provides a linear relationship between the solar irradiation and sunshine duration. Also few 2nd and 3rd degree solar radiation and sunshine duration models are proposed by different authors. Natural events do not have temporal and spatial independent structures. In this paper, three solar irradiation models are used for solar radiation examination in three of the southern cities, Adana, Antakya and Silifke in Turkey. One of these models are proposed in this work as dependency model and this is compared with the Angström–Prescott model and fuzzy logic ANFIS model. The comparison illustrates that dependency model is superior over other approaches. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, on the basis of studying mathematical models of photovoltaic (PV) generation system, a novel maximum power point tracking (MPPT) control method with variable weather parameters is proposed. In this method, the key technologies are finding out the relationship between variable weather parameters and control signal at the maximum power point (MPP) and finding out a way to track the MPP quickly. Through using this proposed method, the MPP can be successfully reached by measuring the solar irradiance and the output voltage and temperature of solar cell. As such, the MPPT control efficiency is raised and the hardware cost of measurement circuits is reduced. Finally, simulated experiments show that this control method can accurately implement the MPP tracking of PV generation system and can have better transient-state performance than conventional P&O method. [Copyright &y& Elsevier]

Abstract: The application of Trombe walls in temperate climates is problematic due to undesired heat gains and overheating phenomena in summer. A proper shading and ventilation of this system can reduce such drawbacks, but the impact of these strategies on the wall’s thermal parameters is yet not widely investigated in quantitative terms. This paper presents an experimental study on the thermal behavior of Trombe walls in summer under Mediterranean climate conditions. The aim of the study is to determine experimentally the thermal parameters of a Trombe wall in summer conditions through the changing of shading, ventilation and operational conditions. In order to do that a series of experimental campaigns were carried out on a case study. A detailed simultaneous monitoring of two Trombe walls made it possible to compare the thermal behavior by varying the screening, ventilation and internal gains conditions. Furthermore, monitoring of indoor thermal comfort conditions and energy simulation using a model in dynamic state were carried out. The results showed that shading, ventilation and occupancy conditions affect significantly the thermal parameters of Trombe wall in summer: screening with roller shutters determines a decrease in internal surface temperature of the wall of 1.4°C and a decrease in daily heat gains of about 0.5MJ/m2; the combined use of overhangs, roller shutters and cross ventilation for the Trombe wall can assure a satisfactory thermal comfort level in summer and a reduction of the cooling energy needs respectively of −72.9% and −63.0% for a dwelling with low or highly insulated building envelope in comparison with the case of an unvented Trombe wall without solar protections. [Copyright &y& Elsevier]

Abstract: For decades, residential and commercial roofs have been considered a prime location for installation of building integrated solar systems. In climatic conditions of East Tennessee, USA, an experimental solar roof was tested during 2009/2010, by a research team representing Metal Construction Association (MCA), and a consortium of building insulation companies, photovoltaic (PV) manufacturers, and energy research centers. The main objective was to thermally evaluate a new roofing technology utilizing amorphous silicon PV laminates integrated with the metal roof panels. In order to mitigate thermal bridging and reduce roof-generated thermal loads, this novel roof/attic assembly contained a phase change material (PCM) heat sink, a ventilated air cavity over the roof deck, and thermal insulation with an integrated reflective surface. During winter, the experimental roof was expected to work as a passive solar collector storing solar heat absorbed during the day, and increasing overall attic air temperature during the night. During summer, the PCM was expected to act as a heat sink, reducing the heat gained by the attic and consequently, lowering the building cooling-loads. In this paper, field thermal performance data of the experimental PV-PCM roof/attic system are presented and discussed. Performance of the PV-PCM roof/attic is evaluated by comparing it to a control asphalt shingle roof. The test results showed about 30% heating and 50% cooling load reductions are possible with the experimental roof configuration. [Copyright &y& Elsevier]

Abstract: In cooling buildings, the use of solar energy can save around 50% of primary energy. Many studies have demonstrated the interest of such systems. However, developing and improving reliability of new components, design, control, and implementation remain a major concern. The performances of solar cooling systems are greatly influenced by climatic conditions. Indeed they affect both the driving energy of the chiller and the heat rejection. It is important to mention that internal loads and control strategy also have an impact on energy performances. Therefore, assessing the energy performance during the design phase is a key point in evaluating the economic interest of an installation. Moreover, once the commissioning of the installation is accomplished, there is a need to follow through and ensure its performance, since a large number of malfunctions can affect the quality of the system. Actual performances can be very different from those calculated in the design phase. With this aim, the present article deals with the development of an absorption chiller model used in an existing solar cooling system. This installation includes a single effect absorption chiller with a nominal chilling capacity of 30kW (EAW LB30 chiller functioning with water and lithium bromide), and it cools four classrooms of a University building in Reunion Island which is situated under a tropical climate. This pilot plant is very good monitored and can thus be used to develop and validate the absorption chiller model. The present paper first recalls the absorption principle and presents the pilot plant, the metrology, and the control strategy. Secondly, the experimental results are analysed and the steady state chiller model and also the identification method are developed. Thereafter, the simplex method is used to determine the design parameters of the machine. Finally, the simulation results are presented. The good agreement between the prediction and the experimental results allows the use of the model not only to design an installation but also to follow and control its performances. [Copyright &y& Elsevier]

Abstract: The development of renewable energy technologies is a critical tool for reducing climate change and the reliance on fossil fuels. However, renewable energy technologies cannot be considered totally clean because they require energy consumption and have environmental impacts that cannot be neglected during their life cycle. In this paper, the life cycle assessment methodology was applied to assess resource use and other environmental burdens related to the entire life-cycle steps of a solar cooling plant. The investigated system works with an absorption chiller assisted by a solar plant. Two back-up configurations (hot back-up and cold back-up) were examined in two localities: Palermo (southern Italy) and Zurich (Switzerland). The benefits in terms of primary energy savings and greenhouse gases emission reduction were demonstrated by comparing the use of this innovative plant in substitution of a conventional one. Energy and CO2eq emission payback times and the energy return ratio of the system were calculated. For all the analysed configurations they ranged from 4 to 6years. A sensitivity analysis related to the calculation of the energy payback time was carried out to assess the influence of various system performance parameters on the payback index. The analysis stressed the following: [–] LCA of renewable energy technologies has to include a detailed analysis of the use phase to assess the benefits that arise from the energy produced by the system during its useful life and to obtain reliable and high-quality LCA results. [–] The use phase is responsible of about 70–90% of the energetic and environmental impacts of the plant life cycle. [–] The innovative plant has a lower environmental impact than the conventional plant. [–] The advantages of renewable energy technologies strongly depend on the climate of the installation site. [Copyright &y& Elsevier]

Abstract: Accurate prediction of building energy performance requires precise information of the local climate. Typical weather year files like test reference year (TRY) and typical meteorological year (TMY) are commonly used in building simulation. They are also essential for numerical analysis of the sustainable and renewable energy systems. The weather year file of one city is often employed by the nearby cities for such purposes. In this paper, the developments of customized weather year formulation are reviewed. The key issues are discussed making reference to two neighboring cities, Hong Kong and Macau, using their weather data records over a century, and the typical weather year files developed. The findings support the preference of TMY over TRY. It is also suggested that the TMY selection process should include the most recent meteorological observations, and should be periodically reviewed to well reflect the long-term climate change. [Copyright &y& Elsevier]