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The paper presents an experimental investigation of a solar dish concentrating system with thermal collectors, along with a numerical investigation of a solar cooling installation based on such system by means of dynamic simulation. The main aim of this study is the analysis of heat generation from the system for heating and cooling purposes, with the use of sorption chillers. A computer simulation of the dynamic operation of the proposed solar heating and cooling system was developed within TRNSYS software. The experimental data were used to validate the model of the concentrator and solar collectors. Successively, a solar heating and cooling installation for a residential application, integrating the different configurations of solar energy collecting devices and thermally driven chillers, was proposed and dynamically simulated. Flat-plate, evacuated tube and photovoltaic-thermal collectors were considered along with absorption and adsorption chiller units. In the present study, different system configurations, localities and time bases were considered to investigate the energy and economic performance of the system. The model of the solar dish and collector arrangement overestimates the produced energy by less than 5% as compared to the experimental study. The results show that the space cooling demand is matched in 23.6 and 46.2% by solar energy in Warsaw, while in Lisbon from 38.2 to 46.1%. The simple payback period of the investigated system configuration was for Warsaw between 18.1 years for the combination of flat-plate collector and absorption chiller and 27.2 year for the photovoltaic-thermal collector with adsorption chiller. • A hybrid solar heating and cooling system was investigated dynamically. • Experiments were performed on flat-plate collectors and dish concentrator set-up. • Different configurations of solar collectors and sorption chillers were investigated. • For Warsaw location, despite a good energy yield, Simple Pay Back is above 18 years. [ABSTRACT FROM AUTHOR]

Highlights • A comprehensive technical and economic evaluation tool was developed. • Pre-defined boundary conditions are available for technical and economic assessment. • Two examples are shown with each one solar thermal and one photovoltaic supported HVAC. • Trends comparing solar thermal and photovoltaic HVAC are reversed for these two cases. • Both technologies can reach cost equity under today's state of the art and boundaries. Abstract Assessing the performance of solar heating and cooling systems, especially cooling systems using solar thermal or photovoltaic driving energy, in a common comparable format, is complicated by the numerous, alternative energy sources and design possibilities. A generalized technical and economic assessment methodology was developed and tested in the course of IEA SHC Task 53. This paper is summarizing the key facts for the assessment and showing the evaluation on the basis of two simulated cases including sensitivity analysis of main boundary conditions. One case is comparing an air/water heat pump with photovoltaic and solar thermal support for a small multifamily house located in Madrid. The second case is comparing a solar thermal driven absorption chiller with a photovoltaic supported heat pump system for a hotel with dominant domestic hot water demand in Innsbruck. The sensitivity analysis shows that photovoltaic and solar thermal systems are cutting across with the same trends. Lower costs have to be derived first, followed by the efficiency of the system. Cost competitiveness is achievable for both technologies with appropriate system design and control strategies. [ABSTRACT FROM AUTHOR]

This paper presents a user-friendly Life Cycle Assessment tool, which aims to support researchers, designers and decision-makers in evaluating the life cycle energy and environmental advantages related to the use of solar heating and cooling (SHC) systems in substitution of conventional ones, considering specific climatic conditions and building loads. The tool was developed within the Task 48 “Quality Assurance & Support Measures for Solar Cooling Systems”, promoted by the International Energy Agency in the framework of the SHC Programme. [ABSTRACT FROM AUTHOR]

The IEA SHC Task 45 Large Scale Solar Heating and Cooling Systems, carried out between January 2011 and December 2014, had the main objective to assist in the development of a strong and sustainable market of large solar heating systems by focusing on high performance and reliability of systems. Within this project, subtask A had the more specific objectives of investigating ways to evaluate the influence that different operating conditions can have on the collector performance, assure proper and safe installation of large solar collector fields, and guarantee their performance and yearly energy output. The results of the different investigations are presented, with a particular focus on how different parameters such as tilt, flow rate and fluid type, can affect the collector efficiency. Other presented results include methods to guarantee and check the thermal performance of a solar collector field and guidelines to design collector fields in such a way that the flow distribution is improved and the risks related to stagnation are minimized. [ABSTRACT FROM AUTHOR]

Abstract: One of the necessary steps to push solar cooling into the market is to define a suitable energy label. The bases for such a label are appropriate testing and rating procedures to which a labelling directive can refer to. Thus a valid and accepted standard for the measurement procedure and performance calculation of solar cooling systems is required. Many different rating methods are available in the field of solar heating and cooling. These comprise different methodical characteristics such as component testing and whole system testing, with the equipment under test measured under steady-state or dynamic conditions, measured in a laboratory, entirely indoor partly outdoor. The output of the measurement is some kind of description of the equipment under test such as performance points or parameters of a model that have been fitted and identified with the measurement data. Based on this input, several approaches for the performance calculation can be observed such as direct extrapolation, look-up tables, frequency distributions or full dynamic simulations. The aim of this paper is to develop a common language for the characteristics applied among the different rating methods in order to help people get acquainted more easily. Firstly general requirements for test and rating methods are brought up. Secondly a classification is proposed which comprises the main characteristics of testing and rating methods as well as options for each of these characteristics. Finally, the classification is applied on the most common European methods for solar heating and cooling systems. [Copyright &y& Elsevier]

Abstract: This paper analyzes different control strategies for the thermal storage management in Solar Heating and Cooling systems (SHC) for different Italian climates. This novel thermal storage system consists in a variable volume storage tank system, which includes three separate tanks and a number of mixers and diverters. Such devices are managed through two different control strategies, based on combinations of series/parallel charging and discharging approaches. Thus, it is possible to vary the thermal storage capacity as a function of the combinations of solar radiation availability and user thermal/cooling energy demands. The system allows one to either increase or reduce the number of active tanks when the occurring mismatch between the solar energy supply and the user demand is either high or low, respectively. In addition, the surplus of solar energy is used through a heat exchanger included in the solar loop for the production of Domestic Hot Water (DHW). This novel variable-volume storage system, in all the proposed configurations, is also compared with a constant-volume storage system from the energetic and economic points of view. In addition, in order to determine the set of the synthesis/design variables which maximize the system profitability, a parametric analysis is implemented. A case study developed for an office building located in different Italian climatic areas is also presented. Simulation results show that the analyzed SHC systems system configurations may be profitable for all those cases and weather locations in which a sufficiently high solar fraction is achieved. [Copyright &y& Elsevier]

This paper presents thedevelopment of a compact and cheap solar heating system based on photovoltaic panels, heat pump and heating storage through a smart regulation from a technical and economical point of view. The heat pump can be standard and have its own regulation. The building's owner may interact with the regulation through a web service to visualize the monitoring of the installation, update the calendar of the presence and change the operation mode. One of the goals of the regulation is to optimize the consumption of his own electricity production and therefore minimize the electricity taken from the grid. Several means are developed to reach the main objective. On one hand, the regulation takes into account the weather forecast to anticipate the future heating's needs and the photovoltaic production. Weather forecast data allows also to optimize the storage in hot water tanks and in the building structure. On the other hand, the project includes the development of an electronic module which collects the monitoring data and gives the commands to the heat pump and the pumps. This is accomplished without any intrusion in the heat pump's own regulation and therefore the user keeps the constructor's warranty. The new regulation was validated numerically. The expected energy gain due to the weather forecast is about 10%, while the one due to the self-consumption and the heat storage management will bring another 10-15%. [ABSTRACT FROM AUTHOR]

Abstract: When rating the performance of a solar cooling system a standardized method is required to calculate seasonal performance figures from measurements at test conditions. A method commonly used for electrical chillers is the so called bin method which utilizes the reference climate as a basic table of temperature and their frequency distribution. When applying this method for solar cooling an additional column is necessary to define the radiation profile of the reference weather. This paper defines a standard radiation profile and describes the applicability of the bin method for solar cooling. It turns out that a simplified reference weather profile creates an uncertainty below 1% onto the calculation of heat gain. The focus in this paper is on solar cooling, however this method may also be used to calculate the gain of solar heating and DHW. [Copyright &y& Elsevier]

Abstract: As the new government came to power, urbanization construction created waves in China, and it will produce hundreds of thousands of billion production value. New-type urbanization has the feature of ecological, energy saving. In this situation, renewable energy especially the lower cost solar energy will play a major role in the urbanization construction. In this paper, we analyzed application potential of SHC (solar energy heating and cooling) and typical cases of Beijing in urbanization construction. [Copyright &y& Elsevier]

Abstract: A reliable solar thermal cooling and heating system with high solar fraction and seasonal energy efficiency ratio (SEER) is preferable. By now, bulky sensible buffer tanks are used to improve the solar fraction for heating purposes. During summertime when solar heat is converted into useful cold by means of sorption chillers the waste heat dissipation to the ambient is the critical factor. If a dry cooler is installed the performance of the sorption machine suffers from high cooling water temperatures, especially on hot days. In contrast, a wet cooling tower causes expensive water treatment, formation of fog and the risk of legionella and bacterial growth. To overcome these problems a latent heat storage based on a cheap salt hydrate has been developed to support a dry cooler on hot days, whereby a constant low cooling water temperature for the sorption machine is ensured. Therefore the need of a wet cooling tower is avoided and neither make-up water nor maintenance is needed. The same storage serves as additional low temperature heat storage for heating purposes allowing optimal solar yield due to constant low storage temperatures. Four pilot installations between 7kW and 90kW nominal cooling capacity were equipped with latent heat storages between 80 kWh and 240 kWh energy content. Annual in situ measurement data shows a positive effect on the seasonal energy efficiency ratio (SEER) for cooling up to 11.4. Furthermore simulation results under different climatic conditions indicate raising efficiency up to 64% compared to a system with solely dry re-cooling. Long-term test bench measuring data concerning performance and durability as well as a new approach for a state of charge detection for latent heat storages are presented as well. [Copyright &y& Elsevier]

Abstract: Solar thermal cooling has difficulty to emerge as an economically competitive solution for small systems mainly due to high investment cost and system complexity [1]. Therefore developments of principally new system solutions are needed. This paper describes such a solution with sorption modules directly integrated into a solar thermal collector. The focus of the work has been to find key parameters influencing the module and the system efficiency. A validated model of a sorption collector has been implemented into a simplified system deck providing cooling, heating and domestic hot water to static loads in the system modelling environment TRNSYS [2]. Simulations have been conducted for different boundary conditions and at two locations with different climatic conditions. Thermal losses from the collector as well as internal thermal losses inside the collector were found to be the most important parameters influencing efficiency. The system simulations gave overall thermal cooling efficiencies in the range of 0.12-0.27 and electrical cooling efficiencies in the range of 15-45 depending on collector technology, climate and control strategy. [Copyright &y& Elsevier]

Abstract: Transparent façade collectors can provide solar heating and cooling and lead to primary energy savings even compared to an opaque wall. They can be simulated with a detailed physical model based on laboratory measurements. The demonstration installation in Ljubljana will provide extensive measurement data of transparent façade collectors in an outdoor environment. This allows a comparison with simulations performed with the model validated by laboratory measurements. This paper presents the demonstration installation and the measurement system, which are based on the new modelling abilities and focused on the outdoor validation of such models. [Copyright &y& Elsevier]

Abstract: In recent years solar hot water systems, solar heating combisystems and solar air conditioning systems have been developed faster in China. Many demonstration projects were built and a technical supporting system including technical code, computer design software and design handbook has been formed. It is introduced that developing situation of technology for solar heating and cooling in China and energy saving effects of some demonstration projects in the paper. [Copyright &y& Elsevier]

Abstract: The availability of solar radiation in phase with the seasonal as well as hourly cooling load profiles in most of the office buildings in the Mediterranean region, in addition to the large share of primary energy consumed for air- conditioning applications in office buildings create a high motivation for the utilization of solar cooling technology for such type of buildings. A solar heating and cooling system for an office building in Italy has been designed, installed and monitored within the framework of the EC co-funded project SOLERA aiming at developing highly integrated solar thermal heating and cooling system that is able to achieve a high solar fraction both for the heating and cooling seasons. The analysis of the system performance during 2011 is presented in this paper, with main focus on electricity consumption during summer. The analysis has been carried out according to the monitoring procedure developed within the frame of the IEA SHC Task 38. [Copyright &y& Elsevier]

Abstract: The objective of Task 44 of the Solar Heating and Cooling program of the IEA is to assess performances and relevance of combined systems using solar thermal and heat pumps, to provide a common definition of performances of such systems, and to contribute to successful market penetration of these new promising combinations of renewable technologies. The Task is also Annex 38 of the Heat pump program and thus called T44A38. It gathers 12 countries and 55 participants.This paper presents the mid term results of the activity, which started in January 2010 and will last until December 2013. [Copyright &y& Elsevier]

Using conventional fossil fuels causes both energy crisis and environmental pollution. Renewable energy with the merits of almost unlimited availability and environmental-friendliness provides a perfect solution to the problem. Solar energy is widely recognized as one of the most important renewable energy resources due to its even distribution, safety and serving as sources for others. In past decades, global solar thermal capacity increases rapidly and now it has been widely used worldwide to provide heating and cooling. To understand the current progress of relevant technologies and the future development, this paper briefly summarizes the current situation of solar heating and cooling, and then some new achievements in related areas and potential future market penetration are discussed. It is found that solar hot water heating system's development is in fast lane in recent years with evacuated tube solar collector dominating the mass market. How to integrate solar collecting system with different types of buildings is the main research and development direction for solar building heating system. Large-scale district water heating system and solar PVT system as the most promising solutions attract extensive attentions. For solar cooling, efforts have been made to improve the efficiency of conventional solar thermal cooling methods in terms of adsorption and absorption technology. In addition to technical development, economic analysis of solar heating and cooling system is also discussed. Return of investment period is widely adopted to evaluate the economic performance. Results reveal that low initial cost and advantageous allowance are the most efficient ways to make solar heating and cooling system economically attractive. This paper is presented and recommended by 5th International Conference on Nuclear and Renewable Energy Resources. [ABSTRACT FROM AUTHOR]

Solar heating and cooling systems are a promising technology which may significantly contribute to the reduction of greenhouse gas emissions, the enhancement of energy efficiency, and the increase of renewables share in the building sector. The available literature show a high number of papers aiming at investigating solar heating and cooling systems based on heat driven and solar technologies, configurations, operating strategies, and financing issues. Nevertheless, none of the papers available in literature investigates the possibility to replace conventional solar thermal collectors by flat plat and concentrating photovoltaic/thermal systems, also producing renewable electricity. To cover this lack of knowledge, in this paper a dynamic simulation model of novel solar polygeneration heating and cooling systems is presented. Such dynamic simulation model is developed and implemented in a computer code, written in MatLab, and allows investigating the energy, economic and environmental performance of such novel solar polygeneration systems, based on both adsorption and absorption chiller technologies fed by dish-shaped concentrating and flat photovoltaic/thermal collectors. In order to show the potentiality of the presented tool, a comprehensive parametric case study is carried out to find out the optimal system configurations, as a function of crucial design and operating parameters and of weather conditions. The presented case study analysis refers to a small cluster of four buildings, including office and residential spaces, located in different European weather zones. The modelled solar polygeneration systems simultaneously produce electricity, space heating and cooling, and domestic hot water; electricity is self-consumed or delivered to the electrical grid. For comparative purposes, two different back-up system configurations, based on an electric chiller and a condensing gas-fired heater are also taken into account as conventional reference building-plant systems. By means of this systematic parametric analysis, comprehensive guidelines for system designers, practitioners and/or researchers focused on the development and use of solar heating and cooling systems are provided. [ABSTRACT FROM AUTHOR]

Abstract: Heat transformation based on adsorption/desorption of water in microporous adsorbents has been considered for the application as adsorption chiller (ACS), adsorption heat pump (AHP) or thermochemical storage (TCS) since the 1980s. Unfortunately, most of the available adsorbents like zeolites were not optimized for the use in these processes as they originally had been developed for gas separation or catalysis processes. Within the last decade, intensive research on adsorbents yielded in improved and very promising new sorption materials with an enhanced adsorption capacity. This work gives a broad overview on current developments on materials including the new class of metal-organic frameworks for the use in adsorption processes for heat storage and transformation. [Copyright &y& Elsevier]

Solar heating and cooling systems for space heating and cooling are experiencing a growing trend and interest. However, the actual energy and environmental performance of small/medium size installations is not clearly foreseeable. In this paper, an analysis of such systems using adsorption chillers in different European climates is presented. Solar systems have been simulated in TRNSYS and compared to a conventional system employing a vapour compression unit. The results have been used for a Life Cycle Assessment (LCA) study, determining the potential impact during the whole life of the system, from raw materials supply to its end-of-life. The LCA has been carried out by using the LCA tool developed in the framework of the International Energy Agency SHC Task 48. Results showed that the useful life of the system is a key parameter: for a useful life of 10 years, the conventional system performs better than the renewable-based one for almost all the locations. However, if a longer life is achieved (15 or 20 years), solar systems show environmental advantage under almost all the climatic conditions: the environmental benefits of using a solar system during the operation step counterbalance the additional impact generated during the other life-cycle steps. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel purposely designed dynamic simulation model for the performance analysis of solar heating and cooling systems is presented. The investigated system layouts are based on single stage LiBr–H2O absorption chillers and on both evacuated tube and concentrating photovoltaic thermal solar collectors. Furthermore, both electric chiller and gas fired heater backup system are considered. Such model is implemented in a computer code written in MATLAB. Here, the optimisation of several system design and operating parameters in terms of energy saving is also carried out. A code to code analysis is performed comparing the obtained simulation results vs. those achieved by a TRNSYS model available in literature. The simulation code for the concentrating photovoltaic thermal solar collectors is validated by experimental data. A good agreement among results is observed in both the cases. A suitable case study referred to a building including both offices and dwellings located in Northern and Southern Italy is presented. High primary energy savings are obtained for some of the investigated system layouts. By evacuated tube collectors solar field such savings can reach 74%, while shifting to concentrating photovoltaic thermal solar collectors they often surpass 100%. The system economic profitability strongly depends on future scale economies and eventual public funding. [Copyright &y& Elsevier]

A solar-heating-and-cooling (SHC) system, consisting of a flat-plate solar collector array, a hot water storage tank, and an absorption chiller unit is designed and modeled to satisfy thermal loads (space heating, domestic hot water, and space cooling). The system is applied for Nicosia, Cyprus, a location with prolonged summer-like conditions, where heating demand is moderate, while space cooling demand is comparatively very high. The study investigates the potential of a solar system installed and operated onsite in a detached single-family household to satisfy all necessary thermal loads. The hot water storage tank is also connected to an auxiliary heater (diesel-fired boiler) to supplement solar heating, when needed. The main purpose of the study is to model the overall system and contact a parametric study that will determine the optimum economic system performance in terms of design parameters. The system is compared, through a cost analysis, to an electric heat pump (EHP) system. It is found that the optimum system combination of solar collector area and volumetric capacity of the hot water storage tank is 70 m 2 and 2000 L, respectively. The total annualized cost (in USD) for the optimum SHC system is $3,719. The sensitivity analysis showed that the SHC system would be unfavorable to compete with EHP technology, if the solar collector cost is above $360/m 2 . [ABSTRACT FROM AUTHOR]

Parametric optimization using dynamic simulation of a solar thermal system for producing hot water, space heating and cooling was developed. The system layouts include a single-effect absorption chiller activated by heat generated by flat plate solar collectors and stored in a solar storage tank. Two construction types were compared; the first is the typical construction in Algeria (low thermal mass with U-values of 1.25 W/m 2 K, single glazing), which represents the majority in the country, while the second is a High-Energy-Performance building (with U-values of 0.35 W/m 2 K, double glazing), representing the pilot project called ECO-BAT. Three of Algeria's regions were considered to evaluate the climatic effect of solar systems integration. Algiers represents the coastal region; Djelfa, the highlands region; Tamanrasset, the Sahara region. In parametric study, two solar collectors' field parameters were analysed, including the surface area and the tilt angle. The results indicated that building loads are significantly reduced (12%, 44% and 22% for Algiers, Djelfa and Tamanrasset, respectively). The solar energy contribution is more than 60% for all cases, a significant contribution for an efficient building. In all cases, we observed that the solar fraction reaches more than 45% when the optimum parameters of the solar system are selected. [ABSTRACT FROM AUTHOR]

Abstract: In the paper, the optimal thermoeconomic configuration of Solar Heating and Cooling systems (SHC) is investigated. In particular, a case study is presented, referred to an office building located in Naples (south Italy); for such building, three different SHC configurations were analyzed: the first one is based on the coupling of evacuated solar collectors with a single-stage LiBr–H2O absorption chiller equipped with a water-to-water electrical heat pump, to be used in case of insufficient solar radiation; in the second case, a similar layout is considered, but the capacities of the absorption chiller and the solar field are smaller, since they are requested to balance just a fraction of the total cooling load of the building selected for the case study; finally, in the third case, the electric heat pump is replaced by an auxiliary gas-fired heater. A zero-dimensional transient simulation model, developed in TRNSYS, was used to analyze each layout from both thermodynamic and economic points of view. In particular, a cost model was developed in order to assess the owning and operating costs for each plant layout. Furthermore, a mixed heuristic–deterministic optimization algorithm was implemented in order to determine the set of the synthesis/design variables able to maximize the overall thermo-economic performance of the systems under analysis. For this purpose, two different objective functions were selected: the Pay-Back Period and the overall annual cost. Possible public funding, in terms of Capital Cost Contributions and/or feed-in tariff, were also considered. The results are presented on monthly and weekly basis, paying special attention to the energy and monetary flows in the optimal configurations. In particular, the thermoeconomic analysis and optimization showed that a good funding policy for the promotion of such technologies should combine a feed-in tariff with a slight Capital Cost Contribution, allowing to achieve satisfactory Pay-Back Periods. [Copyright &y& Elsevier]

In the coming years, it is anticipated that if we continue with the same pace of energy consumption, communities will continue to face three major challenges; a mounting increase in energy demands, pollution, and global warming. On a local scale, Egypt is experiencing one of its most serious energy crises in decades. The energy consumed in indoor cooling and heating is the biggest portion of total energy consumption in residential buildings. This paper is an experimental simulation study for building retrofitting in off-grid settlements in semi-arid climates, using Trombe wall as a low-tech passive heating and cooling solution. In this study, we made developments to the conventional classic Trombe wall using occupant-centered design and living lab experimental methods. The thermal efficiency of the proposed Trombe wall design is simulated during winter and summer peaks. In the proposed design we used gray paint instead of typical black paint in addition to 15 cm reversible natural wool insulation and two 3 mm thick roll-up wool curtains. The new design reduced the heating load by 94% and reduced the cooling load by 73% compared to the base case with an annual energy savings of 53,631 kW h and a reduction in CO 2 emissions of 144,267 kg of CO 2 . The living lab test proved that the proposed design of the Trombe wall is economically viable and the payback time is 7 months. It is recommended that the proposed design be monitored for a whole year to have an accurate assessment of its efficiency. A post occupancy evaluation is also needed to measure local residents’ acceptance and perceived comfort after retrofitting. [ABSTRACT FROM AUTHOR]

The solar heating and nocturnal radiant cooling techniques are combined aiming at a novel solar heating and cooling panel (termed as SHCP) to be easily assembled as construction components for building roofing or envelope and also compatible with surroundings for its versatile coating colors, which can remove the double-skin mode from conventional solar equipment. SHCP has two functions for heating and cooling collecting. In this paper, the heating and cooling performances were analyzed in detail based on a small scale experimental system and effects of air gap and coatings were investigated. The results show that in sunny day of extreme cold January in Tianjin, China, the daily average heat-collecting efficiency is 39% with the maximum of 65%, while in sunny night during hot seasons the average cooling capacity can reach 87 W/m 2 . When two different coatings were sprayed on SHCP without air gap, its heating and cooling performances were all analyzed, the daily average heat-collecting efficiency was 39% and 27% with the maximum points of 65% and 49%, respectively, and the cooling capacity was almost the same of 30 W/m 2 in January. [ABSTRACT FROM AUTHOR]

Abstract: Solar heating and nocturnal radiant cooling techniques are united to produce a novel solar heating and cooling system. The radiant panel with both heating and cooling functions can be used as structural materials for the building envelope, which realizes true building integrated utilization of solar energy. Based on the natural circulation principle, the operation status can be changed automatically between the heating cycle and the cooling cycle. System performances under different climate conditions using different covers on the radiant panel are studied. The results show that the novel solar heating and cooling system has good performance of heating and cooling. For the no cover system, the daily average heat collecting efficiency is 52% with the maximum efficiency of 73%, while at night, the cooling capacity is about 47W/m2 on a sunny day. On a cloudy day, the daily average heat collecting efficiency is 47% with the maximum of 84%, while the cooling capacity is about 33W/m2. As a polycarbonate (PC) panel or polyethylene film are used as covers, the maximum heat collecting efficiencies are 75% and 72% and the daily average heat collecting efficiencies are 61% and 58%, while the cooling capacities are 50W/m2 and 36W/m2, respectively. [Copyright &y& Elsevier]

Abstract: The paper investigates different control strategies for the thermal storage management in SHC (Solar Heating and Cooling) systems. The SHC system under investigation is based on a field of evacuated solar collectors coupled with a single-stage LiBr–H2O absorption chiller; auxiliary thermal energy is supplied by a gas-fired boiler. The SHC is also equipped with a novel thermal storage system, consisting in a variable volume storage tank. It includes three separate tanks and a number of mixers and diverters managed by novel control strategies, based on combinations of series/parallel charging and discharging approaches. The aim of this component is to vary the thermal storage capacity as a function of the combinations of solar radiation availability and user thermal/cooling energy demands. The system allows one to increase the number of active tanks when the time shift between solar energy and user demand is high. Conversely, when this time shift is low, the number of active tanks is automatically reduced. In addition, when the solar energy in excess cannot be stored in such tanks, a heat exchanger is also used in the solar loop for producing DHW (Domestic Hot Water). The analysis is carried out by means of a zero-dimensional transient simulation model, developed by using the TRNSYS software. In order to assess the operating and capital costs of the systems under analysis, an economic model is also proposed. In addition, in order to determine the set of the synthesis/design variables which maximize the system profitability, a parametric analysis was implemented. The novel variable-volume storage system, in both the proposed configurations, was also compared with a constant-volume storage system from the energy and economic points of view. The results showed that the presented storage system allows one to save up to 20% of the natural gas used by the auxiliary boiler only for very high solar fractions. In all the other cases, marginal savings are achieved by the variable-volume storage tanks system. [Copyright &y& Elsevier]

Abstract: This paper presents a dynamic simulation of an innovative polygeneration system based on solar heating and cooling and PEM fuel cells technologies. The polygeneration system is based on the following main components: evacuated solar collectors, single-stage LiBr–H2O absorption chiller and a PEM fuel cell. The fuel cell operates at full load producing electrical energy which is in part consumed by the building lights and equipments. The fuel cell is grid connected in order to perform a convenient net metering. Finally, the system also includes heat exchangers producing domestic hot water in case of scarce space heating/cooling demand. The analysis was carried out by means of a transient simulation model, developed using TRNSYS software and includes the investigation of the dynamic behavior of the building, developed in TRNBUILD. A small university hall, including also a fitness center, was adopted as test case. Energetic and economic models were also developed, in order to assess primary energy savings and the operating and capital costs of the systems under analysis. The results of the case study were analyzed on monthly and yearly basis, paying special attention to the energetic and monetary flows. The results are excellent from the energy saving point of view. On the other hand, the pay back periods can be profitable for the final user only in case of significant public funding. [Copyright &y& Elsevier]

Abstract: Heating, ventilating, and air-conditioning (HVAC) are parts of the major energy consumption in a building. Conventional heating and cooling systems are having an impact on carbon dioxide emissions, as well as on security of energy supply. In this regard, one of the attempts taken by researchers is the development of solar heating and cooling technologies. The objective of this paper is to review the passive solar technologies for space heating and cooling. The reviews were discussed according to the working mechanisms, i.e. buoyancy and evaporative effects. The advantages, limitations and challenges of the technologies have been highlighted and the future research needs in these areas have also been suggested. [Copyright &y& Elsevier]

Abstract: In this paper, the simulation of the performance of solar-assisted heating and cooling systems is analyzed. Three different plant layouts are considered: (i) the first one consists of evacuated solar collectors and a single-stage LiBr–H2O absorption chiller; here in order to integrate the system in case of insufficient solar radiation, an electric water-cooled chiller is activated; (ii) configuration of the secondly considered system is similar to the first one, but the absorption chiller and the solar collector area are sized for balancing about 30% of the building cooling load only; (iii) the layout of the thirdly considered system differs from the first one since the auxiliary electric chiller is replaced by a gas-fired heater. Such system configurations also include: circulation pumps, storage tanks, feedback controllers, mixers, diverters and on/off hysteresis controllers. All such devices are modelled for maximizing the system energy efficiency. In order to simulate the systems’ performance for dynamic heating/cooling loads, a single-lumped capacitance building is also modelled and implemented in the computer code. A cost model is also developed in order to calculate the systems’ operating and capital costs. All the models and the relative simulations are carried out by TRNSYS. A design of experiment procedure is also included. By such tool the effects of the system operating parameters’ variation on the relative energy efficiency are analyzed. In addition, the set of synthesis/design variables maximizing the system’s energetic performance can be also identified. The annual primary energy saving is chosen as the optimization objective function, whereas collector slope, pump flows, set-point temperatures and tank volume are selected as optimizing system design variables. A case study was developed for an office building located in South Italy. Here, the energetic and the economic analysis for all the three considered system layouts are carried out. The simulations’ results are referred to both the initial and the optimized systems configurations. The highest primary energy saving vs. the reference traditional HVAC system is reached by the first considered system layout. The economic performance of the investigated solar heating/cooling systems is still unsatisfactory. The economical profitability of the considered solar heating and cooling systems can be improved only by significant public finding. From this point of view, the best results were achieved by the second above mentioned system configuration. [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: The serious environmental degradation of our planet in the past century and the limitation of supplies of conventional fuels have led humanity to search for new energy forms. The housing sector has a big environmental impact and it makes a good candidate for changes to be implemented in order to make steps towards a sustainable society. This study deals with the exergy analysis and the Life Cycle Assessment (LCA) of solar systems for space heating, cooling and hot domestic water production. These systems will be applied to a residence in the wide Thessaloniki area, in Northern Greece. The analysis is based on the given energy needs of an average house. Furthermore, a photovoltaic system (PV) will be used for electricity production. Besides Solar energy, the existing geothermal field will be utilized via heat pumps. The system is designed to exploit solar and geothermal energy and an exergy analysis of the different elements of the system is performed so that improvements can be achieved in its efficiency and its cost be reduced. It has been shown that the exergy efficiency of the solar systems and the geothermal system are relatively low. Since almost all of the environmental impacts of the renewable energies are connected to the manufacturing of the devises for their utilization, the environmental impacts will be analyzed only at the manufacturing stage. The use of Life Cycle Assessment (LCA) will be used. It has been shown that the use of solar cooling has the highest environmental impact. This analysis applies for all regions since the energy needs could be adjusted and the solar radiation of that region taken into consideration. [Copyright &y& Elsevier]

Abstract: The paper investigates the energetic and economic feasibility of a solar-assisted heating and cooling system (SHC) for different types of school buildings and Italian climates. The SHC system under investigation is based on the coupling of evacuated solar collectors with a single-stage LiBr–H2O absorption chiller; auxiliary energy for both heating and cooling is supplied by an electric-driven reversible heat pump. The SHC system was coupled with different types of school buildings located in three different Italian climatic zones. The analysis is carried out by means of a zero-dimensional transient simulation model, developed using the TRNSYS software; the analysis of the dynamic behaviour of the building was also included. An economic model is proposed, in order to assess the operating and capital costs of the systems under analysis. Furthermore, a parametric analysis and a subsequent mixed heuristic-deterministic optimization algorithm was implemented, in order to determine the set of the synthesis/design variables that maximize system profitability. The results are encouraging, as for the potential of energy saving. On the contrary, the SHC economic profitability can be achieved only in case of public funding policies (e.g. feed-in tariffs), as always happens for the great majority of renewable energy systems. [Copyright &y& Elsevier]

Abstract: In this paper, a transient simulation model of solar-assisted heating and cooling systems (SHC) is presented. A detailed case study is also discussed, in which three different configurations are considered. In all cases, the SHC system is based on the coupling of evacuated solar collectors with a single-stage LiBr–H2O absorption chiller, and a gas-fired boiler is also included for auxiliary heating, only during the winter season. In the first configuration, the cooling capacity of the absorption chiller and the solar collector area are designed on the basis of the maximum cooling load, and an electric chiller is used as the auxiliary cooling system. The second layout is similar to the first one, but, in this case, the absorption chiller and the solar collector area are sized in order to balance only a fraction of the maximum cooling load. Finally, in the third configuration, there is no electric chiller, and the auxiliary gas-fired boiler is also used in summer to feed the absorption chiller, in case of scarce solar irradiation. The simulation model was developed using the TRNSYS software, and included the analysis of the dynamic behaviour of the building in which the SHC systems were supposed to be installed. The building was simulated using a single-lumped capacitance model. An economic model was also developed, in order to assess the operating and capital costs of the systems under analysis. Furthermore, a mixed heuristic-deterministic optimization algorithm was implemented, in order to determine the set of the synthesis/design variables that maximize the energy efficiency of each configuration under analysis. The results of the case study were analyzed on monthly and weekly basis, paying special attention to the energy and monetary flows of the standard and optimized configurations. The results are encouraging as for the potential of energy saving. On the contrary, the SHC systems appear still far from the economic profitability: however, this is notoriously true for the great majority of renewable energy systems. [Copyright &y& Elsevier]

Abstract: Absorption cooling systems based on water/lithium bromide (LiBr) solution typically require an open wet cooling tower to transfer the reject heat to the ambient. Yet, water consumption, the need for water make-up and cleaning, formation of fog, and the risk of Legionella bacteria growth are hindering factors for the implementation of small solar cooling systems. The application of a latent heat storage supporting the heat rejection of the absorption chiller in conjunction with a dry cooling system allows eliminating the wet cooling tower. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours. The system concept and the hydraulic scheme together with an analysis of the energetic performance of the system are presented, followed by a report on the operation of a first pilot installation. [Copyright &y& Elsevier]

Abstract: The chemical heat pumps using monovariant solid/gas reactions and thermal solar energy are potentially interesting for the air-conditioning of building (heating in winter or mid-season and refreshing in summer). They provide a function of storage without loss and potentially at high energy density. The selected reaction involves SrBr2 as reactant and H2O as refrigerant fluid. It is adapted to the thermodynamic constraints in temperature (heat provided by plane solar collector, heating and cooling on the level of the floor) and uses reagents having a weak impact for the environment and health. The reactive salt SrBr2 is implemented with an expanded natural graphite in the form of a consolidated material which has acceptable thermal conductivity and permeability adapted to low pressure. The prototype reactor has a total volume of 1m3. It is able to store, with a complete reaction, 60kWh or 40kWh for the heating or cooling function respectively. This prototype was tested under conditions representative of summer or mid-season; the mean heating or cooling powers, typically about 2.5–4kW, are still insufficient because of a low heat transfer at the interface between the reactive layer and the exchanger wall. However this limitation can be clearly attenuated; that is the subject of current work in following these first experiments. [Copyright &y& Elsevier]

Abstract: Solar energy is receiving much more attentions in building energy systems in recent years. Solar thermal utilization should be based on the integration of solar collectors into buildings. The facades of buildings can be important solar collectors, and therefore become multifunctional. In addition, solar collectors can be used to enhance the appearance of the façade when considering aesthetic compatibility. Currently, the feasible approach for integration of solar collectors into buildings is to install collectors on the south tilted roofs, south walls, balconies or awnings. Experiences on solar thermal utilization were mainly introduced in this paper, which included solar hot water systems with different design methods in residential buildings and solar-powered integrated energy systems in public buildings. Then the suggestions were given. In the cities of China, an ideal opportunity to carry out solar renovation with roof-integrated collectors is in combination with the rebuilding of apartment roofs from flat to be inclined. With regard to multi-storied residential buildings, central hot water supply system and central-individual hot water supply system are more appropriate in view of aesthetic compatibility of solar collectors with building roof and convenience of management. As for public buildings, it is highly recommended to design solar-powered integrated energy systems for the purpose of high solar fraction. [Copyright &y& Elsevier]

• Integrated SHC system driven by PTC and double-effect absorption chiller. • Mathematical model establishment and validation of the whole system. • Comparison of the SHC system and the conventional gas-driven absorption heating and cooling system. • Annual performance investigations and assessments of the SHC system. With the increasing concerns on energy conservation and environmental protection, solar heating and cooling (SHC) system represents an attractive candidate in building sector. In this paper, an integrated SHC system driven by parabolic trough collector (PTC) and double-effect H 2 O/LiBr absorption chiller was presented. The energy generated by solar collectors was supplied to the absorption chiller during the cooling period, and was directly used for space heating with the integration of plate heat exchanger during the heating period. The mathematical models of the whole system including the collector, the double-effect absorption chiller and the plate heat exchanger were established and were validated by field tests. Based on the proposed models, comparison of the SHC system and the conventional gas-driven absorption heating and cooling system was carried out by case study. The annual performances as well as energetic, economic and environmental assessments of the proposed system were investigated. Results show that, 21.3% of the primary energy consumption and 18.8% of the CO 2 emission can be reduced in SHC system. Therefore, the proposed integrated solar heating and cooling system has a promising application prospect in sustainable development in view of its considerable energy saving benefits, potential economic viability and environmental friendly characteristics. [ABSTRACT FROM AUTHOR]

Solar heating and cooling (SHC) systems can be relevant in the achievement of energy and climate European goals. The benefits of these technologies should be evaluated taking into account their life-cycle energy and environmental impacts, calculated by applying the Life Cycle Assessment (LCA). The development of a complete LCA can be difficult and time-consuming particularly for non-experts in LCA, discouraging them in developing the life-cycle assessments. To overcome this issue, the paper presents "ELISA - Environmental Lifecycle Impacts of Solar Air-conditioning systems", a user-friendly simplified tool for estimating the life-cycle energy and environmental benefits/impacts of solar technologies for heating and cooling in different geographic contexts and comparing them to conventional systems. The tool was applied to analyse three systems (thermal SHC, conventional and PV assisted system) in Greece and to identify the one characterized by the best life-cycle performances. The results revealed that the impacts of PV assisted system are about 60% lower than those of the others, highlighting the advantage of using renewable electricity for building air-conditioning in locations with high solar radiation availability. ELISA can be used by researchers, designers and decision-makers to introduce the life-cycle thinking in the early design phase of heating and cooling systems. • ELISA is a tool for developing a simplified LCA of solar heating and cooling technologies. • ELISA calculates the impacts of heating and cooling systems in a specific geographic context. • Three systems installed in Athens (Greece) are examined by combining ELISA with a simulation tool. • The PV assisted system is the best one in terms of life-cycle energy and environmental performance. [ABSTRACT FROM AUTHOR]

Abstract: In this paper the integration of vegetable oil-fed reciprocating engines with solar thermal collector is investigated, seeking to design a novel polygeneration system producing: electricity, space heating and cooling and domestic hot water, for a university building located in Naples (Italy), assumed as case study. The polygeneration system is based on the following main components: concentrating parabolic trough solar collector, double-stage LiBr–H2O absorption chiller and a reciprocating engine fed by vegetable oil. The engine operates at full load producing electrical energy which is in part consumed by the building lights and equipments, in part used by the system passive loads and the rest is eventually sold to the grid. In fact, the engine is grid connected in order to perform a convenient net metering. The system was designed and then simulated by means of a zero-dimensional transient simulation model, developed using the TRNSYS software. The simulation tool developed by the authors allows one to analyze the results for different time basis (minutes, days, weeks, months and years), from both energetic and economic points of view. The economic results show that the system under investigation is profitable, especially if properly funded. [Copyright &y& Elsevier]

Highlights • Experiences of research and demonstration activities were selected and summarized. • Based on that 10 qualitative key principles were expressed within the IEA SHC Task 48. • Background information and recent literature explain the rationales behind. • A survey about the validity and importance of the principles was conducted. • Essential, important and controversial principles can support the design of SHC plants. Abstract The results of past and ongoing activities, in successive IEA SHC (solar heating and cooling) Tasks, suggest enormous potential for solar cooling technologies to reduce greenhouse gas emissions. However, solar thermal cooling still faces barriers to emerge as an economically competitive solution. IEA SHC Task 48 was introduced to gather learnings from existing installations, and to find technological and market solutions, which could enable industry to deliver solar thermal driven heating and cooling systems that are efficient, reliable and cost competitive. The selected experiences of these research activities were clustered into 10 qualitative key principles for successful design and operation of SHC systems. Three existing systems are fully discussed in a solar cooling design guide (Mugnier et al., 2017). This paper aims to introduce these key principles in its general format. The background to the qualitative statements is explained, supplemented with examples from the context of Task 48 and compared with recent literature. Furthermore, a survey was conducted among SHC experts, who provide an assessment of the importance of the principles. The result shows that all principles have their eligibility. However, it turns out that there are three main categories of principles: (i) essential, (ii) important and (iii) controversial. Following the key principles is not a guarantee, but they can support researchers, designers and contractors to implement solar heating and cooling systems successfully. [ABSTRACT FROM AUTHOR]