Search

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.

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.

Energy needs of air conditioning systems are constantly growing worldwide, due to climate change and growing standards of buildings. Among the possible systems, solar heating and cooling based on reversible heat pumps and thermally driven chillers are a viable option for ensuring space heating and cooling for different users. The high installation costs are a limit to their diffusion, however, under specific circumstances (climate, type of the building, type of the user, etc.), the investment in this technology can be profitable in a long term. The presented paper describes an energy-economic assessment of a solar heating and cooling system integrating a solar dish concentrator with thermal collectors coupled with a reversible heat pump and an absorption or adsorption chiller. The system integrated with a household building is developed and dynamically simulated in the Transient System Simulation (TRNSYS) environment under different circumstances –adoption of absorption or adsorption chiller, use of auxiliary thermal energy to drive the sorption chillers, and locality. The results show that space cooling demand in Cracow is matched by solar energy, in a range between 49.0 and 97.6%, while for Naples the space cooling demand is provided by solar heat from 46.1 to 99.1% depending on the adopted sorption chiller and or the use of auxiliary heat for a natural gas boiler. The proposed system is not profitable in case Cracow, since a Simple Pay Back period of about 20 years is achieved. Conversely, case of Naples, the same index achieves a value between 8 and 12 years showing that the proposed system may be a viable solution for heating and cooling installation.

Solar heating and cooling systems can significantly contribute to the energy and climate European goals. A complete assessment of this contribution needs the analysis of these systems from a life-cycle perspective, in order to estimate the energy and environmental costs of their manufacturing and end-of-life, and to compare these costs with the benefits obtained during operation. A well-established methodology to fulfil this task is the Life Cycle Assessment (LCA). The paper describes some LCA experiences of solar heating and cooling systems, developed within the Task 53 “New generation solar cooling & heating systems (PV or solar thermally driven systems)” of the International Energy Agency. The results of these analyses can be useful to orientate manufacturers, researchers and decision makers for a more sustainable use of solar technologies.

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.

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.

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.

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.

Life Cycle Assessment (LCA) is an effective methodology to assess the energy and environmental impacts of energy systems during their life cycle, including manufacturing, operation and end-of-life. The aim of the paper is the application of a simplified LCA tool, developed in the framework of the International Energy Agency Solar Heating and Cooling Task 48, for comparing different typologies of solar assisted heating and cooling systems. In detail, solar thermal heating and cooling systems located in Palermo (southern Italy) and in Zurich (Switzerland) were compared with conventional systems assisted by grid connected and stand-alone photovoltaic plants. A validation of the tool was also carried out by comparing the obtained results with those of in-depth LCA studies. The results showed that the best system configuration in Palermo is the conventional system assisted by a grid-connected photovoltaic plant. Its impact on global energy requirement is about 83.7% and 74.5% of the corresponding impact of the solar thermal heating and cooling and the conventional system assisted by a stand-alone photovoltaic system, respectively. Different considerations can be made for Zurich, where the solar heating and cooling system performs better than the others; it is characterized by a global energy requirement that is 85.3% and 81.2% of the grid-connected and stand-alone photovoltaic assisted conventional systems, respectively. A similar trend is traceable for the global warming potential indicator. The validation of the LCA tool proved it to be reliable since deviations with a detailed LCA of the same system are contained below a 5% difference in all the comparable systems.

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.

The application of solar heating and cooling systems for building air-conditioning actually shows a significant potential of exploitation, particularly in sunny regions. The choice whether or not to apply such technologies in different climates should be based on the assessment of their energy/environmental, economic and social sustainability, as well as their technical characteristics as reliability, durability and energy efficiency. To support researchers and decision-makers in the selection of the best solar air-conditioning solution in a specific geographic and energy context, the paper proposes a set of technical, economic, energy/environmental and social key performance indicators. The research activity was developed within the Task 53 “New generation solar cooling & heating systems (PV or solar thermally driven systems)” of the International Energy Agency.

The paper investigates the introduction of a solar heating and cooling system in an office building characterized by low energy demand with respect to the current national building stock and located in Southern Italy. Dynamic simulations are carried out in order to evaluate the thermo-economic performance of the analyzed system considering different solar panel technologies (flat plate and evacuated tube), tilt angles (10–70°), collecting areas (30–60 m 2 ), hot and cold storage sizes, reference emission factors, electricity and natural gas unitary prices. To satisfy cooling demand a small scale adsorption chiller activated by thermal energy available from solar collectors is considered. The solar heating and cooling system demonstrated primary energy saving and equivalent dioxide carbon emission reduction higher than 23% in comparison to the reference conventional system. The results show that the solar energy system will be competitive when the electricity and natural gas prices will be high and strong government incentives will be provided.

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.

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.

Conventional heating and cooling systems are responsible for large amounts of carbon dioxide release to the environment, as well as for the use of harmful refrigerants regarding the greenhouse effect and the ozone depletion potential. Solar radiation is a clean form of energy, which is required for almost all natural processes on earth. In South Africa, the majority of produced electricity is generated from fossil fuels and the potential of renewable energy sources is vast, solar radiation in particular is in abundance. The upper limit for Global Horizontal Irradiance (GHI) in South Africa can be as high as 2 300 kWh/m2/a, whereas the Direct Normal Irradiance (DNI) value attains a maximum of 2 900 kWh/m2/a, which is significantly higher than it is in other regions worldwide. The global air conditioning systems market has been estimated to reach 78.8 million units by 2015 due to increasing living standards, comfort expectations and global warming. South Africa is not the best performer regarding renewable energy use among African countries and there is a long way to go to achieve a sustainable environment. This paper seeks to investigate the feasibility and the sustainability of solar driven air conditioning system in South Africa based on meteological weather data. Currently, renewable energy is a topic of interest in South Africa after the 2008 energy emergency when power outages were rolled out due to inadequate maximum load planning. Solar air conditioning technology remains an untapped technology in South Africa.

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%.

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/m2. 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/m2 in January.

A residential solar-heating-and-cooling (SHC) system is a possible alternative for the reduction of fossil fuel consumption to cover residential energy loads. These systems can cover all thermal loads, i.e. space heating, space cooling and domestic hot water preparation. Space cooling is fulfilled through a heat-activated (hot water), single-effect LiBr-water absorption chiller. Proper operation of such a system requires coupling of the solar collector array to a hot water storage tank with auxiliary heating. Auxiliary heating, in this case in the form of a diesel-fired boiler, is necessary to supplement heating in the storage tank when demand exceeds solar heating availability. In this study emphasis is given on the effect of the collector tilt angle (slope) on the performance of a SHC system. A constant slope throughout the year simplifies system configuration and maintenance, but on the other hand a variable slope improves performance, in terms of energy efficiency, and thereby lowers the operating cost of auxiliary heating. The results of the study show that it is economically beneficial to vary the slope throughout the year (on a monthly basis), since $233/year can be saved when a variable slope is used.

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.

This paper presents the design and performance analysis of a solar thermal heating and cooling (SHC) system. Apart from year-round domestic hot water (DHW) heating and space cooling, the specific system design provides the possibility to utilize waste heat of absorption chiller (ACH) during cooling operation for DHW preheating. This system was designed and set up as a first pilot plant on northern Adriatic coast of Croatia to ensure better assessment of technical and economic feasibility of SHC systems in that area through monitoring during operation. Following the system configuration design with original control system parameters, a detailed TRNSYS dynamic simulation model is developed. A methodology for validation of simulation model on a level of complete SHC system is proposed. The presented approach comprises simulation of the control system and interaction between system components, thus enabling reliable application of simulation model for further improvements of a particular system. Monitoring and simulation data showed satisfactory performance of SHC system. 55% of total irradiated solar energy is utilized at solar collectors, measured seasonal chiller efficiency ratio is 0.68 and running costs are 0.0225 € per kWh of produced cooling energy. Monitoring data also indicated that, due to unexpected low DHW consumption of the particular system compared to design guidelines, only 8% of heat from condenser and absorber is recovered, while the rest of the heat is rejected to surroundings at the cooling tower. Using the simulation model, a set of scenarios with increased DHW consumption and improved heat exchanger parameters were investigated in order to overcome the issue of low heat recovery efficiency. Preliminary analysis for analyzed period showed possibility for recovery up to 53% of waste condenser and absorber heat, reduction of cooling energy price by 15% and reduction of total system running costs when heating and cooling are both considered. The developed simulation model has been proven as valuable tool for evaluation of energy balances and feasibility analysis as well as for system configuration analysis and performance enhancement and it will be used for further research in order to achieve optimal efficiency in year-round operation.

The solar heating and cooling system simulation platform has been established based on Trnsys in this paper. Taken the villa building in cold areas of China as research objects, the solar heating and cooling system with different solar energy resources division have been analyzed. System optimization designs have been proposed and the optimum storage tank volume and solar fraction of the solar heating and cooling system have been given. The results show that the solar irradiation is one of the most influence factors in solar heating and cooling system for storage tank volume and solar fraction. The higher solar irradiation can be acquired, the larger volume of storage tank and solar fraction.

This chapter presents a review of nontracking solar thermal collectors. These collectors are suitable for low to medium temperature applications with a maximum of about 150°C. This range of temperatures is particularly suitable for solar heating and cooling applications. Usually these collectors collect both direct and diffuse solar radiation, so they are very effective collection devices. For this purpose there is no requirement to follow the sun trajectory during the day so they belong to the nontracking collectors. Some of the types presented may require seasonal tracking, ie, changing the tilt angle of a collector a few times per year. The frequency of tracking increases with the concentration ratio. Higher concentration ratio leads to higher collector operating temperature but also to higher tracking accuracy requirements. The types of collectors examined in this chapter are the flat plate collector, which is the most used collector type, and its variations, the diffuse reflector, reverse flat plate collector, compound parabolic collector, and evacuated tube collector.

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.

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.

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.

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 47 W/m 2 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 33 W/m 2 . 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 50 W/m 2 and 36 W/m 2 , respectively.

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.

The solar heating and cooling systems are among the best solutions for the current energy and environment issues. In this chapter, the background and overview of the solar heating and cooling systems are given. In these systems, the energy sources are the solar power, and the consuming components include the heating and cooling devices. In order to ensure the steady operation of solar driven systems, the heat storage systems are also necessary. In this case, the different choices of solar energy, solar heating, solar cooling and heat storage are briefly introduced in this chapter. A technology roadmap is given at last which provides a clear connection between these introduced technologies.

This chapter discusses the aspects that should be considered when selecting the latent heat storage for a specific solar heating and cooling application. It positions latent heat storage in relation to solar heating and cooling systems helping determine the storage size and the temperature level. It quantifies temperature losses and indicates how the major sources of irreversibilities can be quantified. It shows how the savings related to energetic performance can be determined. It distinguishes between stationary phase change materials (PCMs) and pumpable slurries of PCMs, and it illustrates the advantages of pumpable PCM slurries. Finally, a method is proposed to estimate the performance of different storage/heat exchanger concepts and a procedure for the selection of a latent heat storage type is proposed.

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.

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.

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.

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.

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 6 years. 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.

In this study the model of a Solar Heating and Cooling (SHC) system and its experimental setup are presented. The SHC system under investigation is a demonstration plant installed in Naples, based on flat plate solar collectors and a single-stage LiBr-H2O absorption chiller. In addition, two vertical tanks are installed as storage system. The balance of system includes: A cooling tower, pumps, valves, safety devices and pipes. The absorption chiller is powered only by solar energy, since there are devices for auxiliary thermal energy. The experimental setup also includes a number of meters (temperature, pressure, flow rate and radiation) to measure, collect and control the prototypal system. The experimental plant is dynamically designed and simulated in order to calculate its energetic and economic performance parameters. This analysis is carried out by means of a zero-dimensional transient simulation model, developed by using the TRNSYS software. Furthermore, a parametric analysis is implemented, aiming at determining the set of the synthesis/design variables that maximize system performances. The model was validated by the first experimental results obtained by the operation of the solar cooling system. Results show that, although flat-plate solar collectors have been specially designed for this kind of application, their operating temperature is often too low to drive the absorption chiller. In addition, the system performance is not particularly sensitive to the storage volume whereas the thermal capacity of the solar field is lower than the absorption chiller demand, determining a very discontinuous operation of the chiller itself.

Advanced energy storage is an essential key technology for adjusting the time discrepancy and instability between solar energy supply and energy demand in solar heating and cooling systems. Among the various energy storage technologies, the thermochemical energy storage method has received more attention because of its distinct advantages of higher energy storage density and low heat loss compared with the conventional sensible and latent energy storage methods. The development of thermochemical energy storage technology is reviewed in this chapter. A lot of theoretical and experimental studies on reactants, chemical reaction kinetics, and system designs are introduced and analyzed, and the future development of thermochemical heat storage is discussed.

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.

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.

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 1 m3. It is able to store, with a complete reaction, 60 kW h or 40 kW h 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 2.5–4 kW, 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.

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 facade 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.

A solar tracker can keep the collector’s aperture perpendicular to the incident light to maximize the solar radiation, so it is a key component to improve the performance of solar collector. In this chapter, the composition and types of solar tracking are summarized, and the applications of various technologies are demonstrated respectively.

Renewable energy sources compete with conventional fuels in three distinct markets: hot water and space heating, power generation, and transport fuels. Hot water for sanitary uses as well as space heating for millions of buildings is supplied by systems that employ solar energy. In this chapter, a brief overview of the global solar thermal market is presented. Furthermore, the main solar thermal technologies for heating and cooling are presented, as well as methods that can be used to estimate the environmental impact of various technologies and systems and their implementation on solar technologies.

Solar Heating and Cooling systems are a virtuous alternative to conventional air conditioning plants, as a renewable energy source (solar energy) is exploited. In this paper the coupling of low temperature solar devices with an innovative desiccant-based air handling unit, which meets the sensible and latent loads of a simulated lecture room, is analyzed through TRNSYS dynamic simulation software. The components have been characterized by means of experimental tests carried out at the test facility of Università degli Studi del Sannio. The desiccant-based air handling unit current set-up allows summer operation only. However, heating operation is also simulated, as comfort conditions can be maintained in the conditioned space exploiting solar thermal energy also in winter, with some modifications to the air handling unit. A parametric analysis is performed to compare different technical solutions (collector types, surface, tilt angle) and to identify the optimal one, taking into account energy, economic and environmental performance with respect to a reference system. The best case in terms of energy and environmental performance is represented by evacuated collectors, achieving a primary energy saving of 64% and a CO2 emissions reduction of 61%; flat-plate collectors are instead the best solution in terms of pay-back period (6 years).

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–H 2 O 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.

Solar heating and cooling (SHC) technologies exploit solar irradiation to either produce heat or, alternatively, provide air conditioning. The basic principle behind cooling is the sorption process by which coldness is generated by the evaporation of a solvent that is later adsorbed into another medium. Solar collectors for heating can be divided into flat-plate or air collectors, evacuated tube collectors and unglazed panels. In the case of air conditioning, the dominant technologies being used today are: closed chillers, which use either liquid or solid sorption materials, and open cooling cycles. In this chapter, different analyses about technology trends and how cost can be close to conventional heating and cooling systems are exposed. Moreover, it is appreciated how solar cooling systems operate more efficiently than for heating since the peak energy demand closely coincides with the highest solar irradiation. Within the field of SHC long-term energy storage is also considered to hold the heat (warm or cold) over time.

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–H 2 O 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.