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Abstract This paper reviews the state-of-the-art cooling methods of photovoltaic (PV) modules and evaluates the performance of the radiative cooling method in detail. Higher operating temperatures of PV modules cause degradation of conversion efficiency and long-term reliability. To overcome this drawback, active or passive cooling methods using heat pipe, natural/forced air flow, forced water flow, phase change material, direct liquid immersion/submerging, and passive heat sink have been studied. In this paper, the methodologies and cooling effects of various cooling methods in the literature are summarized to provide a comprehensive overview of the current cooling technologies. Then, the performance of the radiative cooling method, which is simple and passive (zero power consumption) method, is quantitatively evaluated based on a detailed heat transfer model considering sky radiation properties in four typical climate conditions. Daily heat budgets of the PV modules with different surface emissivity spectra are simulated to estimate the solar cell temperature. The results indicate that modification of the surface emissivity spectrum hardly contribute to the radiative cooling enhancement under any climate conditions, as compared to the conventional glass cover. The present findings serve as a guide for future research and development of better cooling methods. Highlights • Comprehensive literature review of PV module cooling methods. • Radiative cooling methods are simple and passive, thus attractive. • Radiative cooling performance of typical silicon PV module is evaluated for four typical climates. • Modifying surface emissivity spectrum hardly contributes to radiative cooling enhancement. [ABSTRACT FROM AUTHOR]

This paper reviews, for the first time, the measurement adsorption characteristics techniques to facilitate optimal testing of the validity of adsorbent materials in adsorption applications. Thermo-physical properties, adsorption characteristics and modelling techniques are presented. The characterisation of material thermo-physical properties includes true and bulk densities, specific heat capacity, surface area, pore volume distribution and thermal conductivity. The adsorption characteristics were categorized into adsorption isotherms and kinetics including experimental and theoretical equations. A range of models used in the simulation of adsorption cooling systems is presented and discussed. The paper highlights the conditions for which each measurement technique is most suitable and the limitations of modelling techniques, which is a vital element in the robust assessment of the performance of adsorption cooling units. [ABSTRACT FROM AUTHOR]

Cooling the operating surface is a key operational factor to take into consideration to achieve higher efficiency when operating solar photovoltaic systems. Proper cooling can improve the electrical efficiency, and decrease the rate of cell degradation with time, resulting in maximisation of the life span of photovoltaic modules. The excessive heat removed by the cooling system can be used in domestic, commercial or industrial applications. This paper presents a review of various methods that can be used to minimize the negative impacts of the increased temperature while making an attempt to enhance the efficiency of photovoltaic solar panels operating beyond the recommended temperature of the Standard Test Conditions (STC). Different cooling technologies are reviewed, namely Floating tracking concentrating cooling system (FTCC); Hybrid solar Photovoltaic/Thermal system cooled by water spraying; Hybrid solar Photovoltaic/ Thermoelectric PV/TE system cooled by heat sink; Hybrid solar Photovoltaic/Thermal (PV/T) cooled by forced water circulation; Improving the performance of solar panels through the use of phase-change materials; Solar panel with water immersion cooling technique; Solar PV panel cooled by transparent coating (photonic crystal cooling); Hybrid solar Photovoltaic/Thermal system cooled by forced air circulation, and Solar panel with Thermoelectric cooling. Several research papers are reviewed and classified based on their focus, contribution and the type of technology used to achieve the cooling of photovoltaic panels. The discussion of the results has been done based on the advantages, disadvantages, area of application as well as techno-economic character of each technology reviewed. The purpose of this review is to provide an understanding for each of the above-mentioned technologies to reduce the surface temperature of the PV module. The study will focus on the surface temperature reduction array bound by each of the cooling technologies. The performance of each cooling technology will also be highlighted. In addition to this study, this review will include a discussion comparing the performance of each cooling technology. The outcomes of this study are detailed in the conclusion section. This paper has revealed that any adequate technology selected to cool photovoltaic panels should be used to keep the operating surface temperature low and stable, be simple and reliable and, if possible, enable the use of extracted thermal heat to enhance the overall conversion efficiency. The presented detailed review can be used by engineers working on theory, design and/or application of photovoltaic systems. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) technologies incorporating phase change materials (PCM) are proving viable option for achieving energy efficiency economically in the buildings. This paper reviews the application of air-PCM-TES studies and technologies for the free cooling and heating of buildings. TES in general and air-PCM-TES in particular are discussed in this review. An extensive investigation on air-PCM-TES systems has been undertaken through passive and active methods and the advantages and disadvantages for each, are detailed. The thermal performances of these systems have been investigated through experimental and numerical approaches and listed in this paper. Passive methods e.g. use of PCMs in the building envelope present difficulty of exchanging a high rate of heat and therefore unsuitable for extreme climate. Therefore, active methods are adopted for extreme climates to meet the demand. Overall, when the right method is applied, air-PCM-TES systems have shown to be effectively providing free cooling and heating of the buildings through auxiliary sources. [ABSTRACT FROM AUTHOR]

Reduction of energy consumption is a major concern in vapor compression cooling systems, especially in areas with very hot weather conditions. In hot weather conditions, performance of these systems decrease sharply and electrical power consumption increases considerably. Evaporative condensers enhance the heat rejection process by using the cooling effect of evaporation and therefore improve energy-usage efficiency. This paper presents an extensive review of the state of the art of evaporative condensers used in residential cooling systems: refrigeration, air-conditioning, and heat pump systems. The paper primarily concentrates on the energy consumption of residential cooling systems worldwide and its related problems. In addition, the paper covers the operation principles of evaporative-condensers, theory of heat rejection, and water evaporation rate. Finally, comparison between different types of condensers is presented. It is found that by using evaporative-cooled condenser instead of air-cooled condenser, the power consumption can be reduced up to 58% and the coefficient of performance can be improved by about 113.4% with systems of different cooling capacities ranging from 3 to 3000 kW. [ABSTRACT FROM AUTHOR]

Adsorption-based desalination attracted increasingly attention due to its ability to co-generate double distilled fresh water and cooling effect using only one heat input. The system employs a combination of flash evaporation and thermal compression. This paper presents the current literature review on the dual effect (cooling and desalination) adsorption desalination system (ADS), which is an emerging process of thermal desalination with cooling utilizing low-grade heat source. The paper also presents the adsorbents suitable for adsorption–desalination systems, performance of ADS, and the thermodynamic analysis of the adsorption desalination cycle. A comparison between the stated ADS has been also presented in this study. [ABSTRACT FROM AUTHOR]

The term “polygeneration” is referred to as “an energy supply system, which delivers more than one form of energy to the final user”, for example: electricity, heating/cooling, desalination can be delivered from polygeneration process. The polygeneration demonstrates unique integration of energy efficiency and renewable energy. It is the next generation energy production technique with a potential to overcome intermittence of renewable energy, reduce cost of power generation and greenhouse gas emissions. The feasibility study of this paper is divided in three sections: In first section of this study, solar and biomass have been arranged to produce steam for power generation. In the second section, cooling is produced by vapor absorption refrigeration (VAR; LiBr-H 2 O) system as per demand load requirement using steam, extracted from pass-out turbine. In the last section of this paper, multi effect dehumidification (MED) water desalination is produced by using limited amount of heat from water vapor (refrigerant; H 2 O) through HE1 of VAR cooling system. [ABSTRACT FROM AUTHOR]

The air conditioner should control the building sensible and latent load properly in order to provide the indoor comfort conditions. The conventional mechanical vapor compression system usually controls the latent load by the process of condensation of water vapor in which air is cooled below its dew point temperature and then reheated again up to the required supply conditions. The conditions where latent load is dominant these two processes i.e. overcooling and then reheating again will increase the consumption of electrical energy and emission of CO 2 remarkably. To avoid this wastage of primary energy and emission of harmful gases, desiccant based evaporative cooling system is a good alternative to traditional air conditioning system which is cost effective as well as environment friendly. It can be driven by thermal energy which makes a good use of solar energy which is free as well as clean. In this paper, a review of desiccant based evaporative cooling systems has been presented. The present study is undertaken from variety of aspects including background and need of alternative cooling systems, concept of conventional and desiccant based evaporative coolers, system configurations, operational modes, as well as current status of the desiccant based evaporative cooling technology. The review work indicated that the technology of desiccant based evaporative cooler has a great potential of providing human thermal comfort conditions in hot and humid climatic conditions at the expense of less primary resources of energy as compared to conventional cooling systems. Some modified and modern evaporative coolers have also been introduced in this paper. [ABSTRACT FROM AUTHOR]

There is no dearth of published data concerning direct evaporative cooling, especially concerning the wetted media used in this technique. In spite of the data abundance, the lack of a comprehensive review of wetted media with potential use for inlet air pre-cooling of Natural Draft Dry Cooling Towers (NDDCTs) triggered the motivation of this paper. This paper reviews the wetted media with potentiality in the pre-cooling application of NDDCTs in terms of wetted medium types, mathematical models, performance studies and empirical relations. A method to compare wetted media in terms of the balance between cooling potential and pressure drop is proposed and validated. This method should be useful for comparative evaluation of wetted medium types or at least to differentiate between good and bad medium types. The medium cost, the service life, the type of process to be cooled, environmental conditions, water quality, space availability, locations and economic requirements are essential considerations, and some significant trade-offs have to be made during medium selection. A framework for medium selection is presented and the advantages and disadvantages of different medium types are summarized to provide a starting point for such selection. The empirical correlations appeared in the literature are synthesized to better correlate and compare the test data of wetted media and subsequently to provide prerequisite information for performance prediction. Controversies concerning wetted medium studies are discussed, and finally the gaps related to wetted medium studies are articulated. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to provide a source of information on thermal energy use in buildings, its drivers, and their past, present and future trends on a global and regional basis. Energy use in buildings forms a large part of global and regional energy demand. The importance of heating and cooling in total building energy use is very diverse with this share varying between 18% and 73%. Biomass is still far the dominant fuel when a global picture is considered; the role of electricity is substantially growing, and the direct use of coal is disappearing from this sector, largely replaced by electricity and natural gas in the most developed regions. This paper identifies the different drivers of heating and cooling energy demand, and decomposes this energy demand into key drivers based on a Kaya identity approach: number of households, persons per household, floor space per capita and specific energy consumption for residential heating and cooling; and GDP, floor space per GDP, and specific energy consumption for commercial buildings. This paper also reviews the trends in the development of these drivers for the present, future – and for which data were available, for the past – in 11 world regions as well as globally. Results show that in a business-as-usual scenario, total residential heating and cooling energy use is expected to more or less stagnate, or slightly decrease, in the developed parts of the world. In contrast, commercial heating and cooling energy use will grow in each world region. Finally, the results show that per capita total final residential building energy use has been stagnating in the vast majority of world regions for the past three decades, despite the very significant increases in energy service levels in each of these regions. [ABSTRACT FROM AUTHOR]

The use of nanofluids for cooling is an attracting considerable attention in various industrial applications. Compared with conventional fluids, nanofluids improve the heat transfer rate, as well as the optical properties, thermal properties, efficiency, and transmission and extinction coefficients of solar systems. The effects of different nanofluids on the cooling rate and hence the efficiency of solar systems can be experimentally investigated. Accordingly, this review paper presents the effects of nanofluids on the performance of solar collectors from the considerations of efficiency and environmental benefits. A review of literature shows that many studies have evaluated the potential of nanofluids for cooling different thermal systems. The second part of this paper presents an overview of the research, performance, and development of photovoltaic/thermal (PV/T) collector systems. Descriptions are made on water PV/T collector types, analytical and numerical models, and simulation and experimental works. The parameters affecting PV/T performance such as covered versus uncovered PV/T collectors, absorber plate parameters, and absorber configuration design types are extensively discussed. Exergy analysis shows that the coverless PV/T collector produces the largest total (electrical+thermal) exergy. Furthermore, PV/T collectors are observed to be very promising devices, and further work should be carried out to improve their efficiency and reduce their cost. Therefore, using nanofluids for cooling PV/T systems may be reasonable. [ABSTRACT FROM AUTHOR]

By exploiting the 3 K coldness of outer space as heat sink of terrestrial thermal radiation, passive daytime radiative cooling (PDRC) can achieve sub-ambient temperatures without any energy consumption, and thus exhibiting extraordinary application potentials. By pursuing the dual-band (solar and atmosphere window) optical properties to approach ideal 100 %, PDRC can maximize dissipating long wavelength infrared radiation to space and minimize absorbing sunlight simultaneously. PDRC technology can reach146 W/m2 theoretical cooling power and up to 120 W/m2 during application. This article focuses on the fundamental physics mechanism of radiative transfer and natural radiative cooling phenomena. Methodologies of infrared absorption functional group selection, optical band gap selection for solar reflection, photon and phonon enhanced resonance by micro-structure were discussed in detail to give a comprehensive instructing strategy of radiative cooling power improvement. Although PDRC technology can achieve sum-ambient temperature cooling without consuming any energy, its drawbacks such as single function of cooling and high whiteness requirement needed to hinder its large-scale application. This article also outlines the current primary applications of PDRC technology, along with summarizing the challenges and potential opportunities it encounters in practical implementation. This paper aims to provide a comprehensive overview on the fundamental physical mechanisms, methods for enhancing its power output, as well as the current state and future developments of PDRC applications, providing potential guidance for reducing greenhouse gas emissions and energy consumption. • Advancements of radiative cooling technology were reviewed comprehensively. • Fundamental physics of passive radiative cooling was reviewed comprehensively. • Material selection methodology and optical mechanism were discussed in detail. • The recent application of passive daytime radiative cooling was reviewed. • Some current challenges and potential applications were presented and discussed. [ABSTRACT FROM AUTHOR]

Implementing Nature-Based Solutions (NBS) is a promising way to reduce building energy demand and facilitates the achievement of United Nations Sustainable Development Goal 7, as they provide shading, evapotranspiration cooling and other influences on buildings. Although this field has attracted much attention, uncertainty persists regarding the potential of different NBS types to impact building energy demand in different climate conditions. To clarify this uncertainty, 101 papers were studied based on the Web of Science and Scopus databases. The current status analysis explored the development state of this field. Building energy performance analysis evaluated the potential reduction in cooling and heating energy in different climates by applying different NBS types at building scale. The review revealed that the cooling energy saving potential of NBS varies from 3% to 90%, while the potential reduction in heating energy demand ranges from 0.58% to 60%. The extent of the reduction in both cases is dependent on the NBS type and climate. Notably, some NBS types may lead to an increase in heating energy demand by between 5.9% and 25% in climates with short and mild winters. This review found that maximizing the energy-saving potential of NBS requires a comprehensive consideration of multiple factors rather than maximizing an individual factor. Further, most studies in this field have only concentrated on a few NBS types and climate zones, resulting in significant differences in research depth among different NBS categories. Future work should focus on neglected NBS types and climates to fully understand their energy-saving potential. • Different types of nature-based solutions regarding building energy demand reduction were reviewed. • Climate zone dependency of NBS impact on building energy demand was analyzed and quantified. • Influential factors to optimize the impact of nature-based solutions on building energy performance were identified. • Research gaps regarding nature-based solutions impact on building energy demand were identified. [ABSTRACT FROM AUTHOR]

Wind energy continues to stand out as a more established and mature technology to offset a large proportion of power. Efforts aimed at improving wind energy use to meet the energy demand in turbulent urban wind environment have been the main technical focus. In previous studies on wind resource and behavior in urban environment, different designs of horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs) have been reviewed. This paper vividly captures the fact that wind resource has a great potential to be fully explored and developed in the urban environment. Varying ways of application and application techniques being applied for electrical generation, ventilation and pollution dispersion, onshore cooling and dehumidification of coastal urban cities, and economics and environmental benefits of applying wind energy in urban environments are summarized. Although many new ideas and solutions that factor technical, economical and environmental sustainability in urban areas are coming up every day, challenges in design are gradually being solved to take advantage of urban low and turbulent wind speed characteristics, installation space challenges, vibration and noise reduction, among others. Some of the unique solutions that have been and are being developed in the applications of wind energy technology in urban environments are also reported in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the annual and seasonal cooling (CDD) and heating (HDD) degree day values over Saudi Arabia by utilizing the long-term daily average temperatures from 38 meteorological stations. The values of CDDs and HDDs have been calculated for a base temperature of 18.3°C. The maximum annual mean CDDs of 7549 were observed at Makkah while the minimum of 3132 at Abha. On the other hand the maximum HDDs of 985 were found in Guriat and minimum of 0 at Gizan, Jeddah, Rabigh, Makkah, Sabya, Sharourah, Wejh and Yanbu. The annual and seasonal values of CDD and HDD provided in this paper could be used to estimate the fuel or energy requirement for cooling or heating of buildings in respective areas both on annual and seasonal bases. [Copyright &y& Elsevier]

Abstract: Globally, buildings are responsible for 40% of the total world annual energy consumption which is responsible for one-third of green house gas emissions around the world. A significant portion of this energy is used for lighting, heating, cooling, and air conditioning purposes in buildings. Increasing awareness of the environmental impact of green house gas emissions and CFCs triggered a renewed interest in environmentally friendly cooling, and heating technologies for buildings. Free cooling of buildings may be seen as an alternate to compressor based air conditioning systems used for the buildings. In free cooling, nighttime cold is accumulated in storage material and extracted when needed. Latent heat storage using phase change materials (PCMs) can be used for free-cooling purposes due to their high storage density. In free cooling, using PCM as storage material, cool air during night is used to solidify the PCM and the accumulated cold is extracted during the hot day times. In this article a detailed review of work conducted by different researchers on PCM based free cooling is presented. Major challenges being faced in the design of PCM based free cooling system such as phase change materials; their thermo-physical properties and the geometry of encapsulation are elaborated and discussed in detail. Also the parameters effecting the charging and discharging of PCM, effect of phase change temperature and climatic conditions on thermal performance of the free cooling system are also discussed. Potential reduction in CO2 emissions due to the applicability of free cooling systems in residential and commercial buildings is also discussed in this article. This paper also provides a comprehensive list of the PCMs currently being used and that can be used potentially for free cooling applications. At last, this paper also presents some current problems needed further research in this area. [Copyright &y& Elsevier]

Abstract: Energy flow from the primary energy to the final energy use varies depending on which device is used for the heating and cooling energy service. This paper presents economic analyses of medium capacity space heating and cooling systems from three perspectives – primary energy, final consumer, and social cost perspective. From the analysis results of primary energy and final consumer perspective, electric heat pump (EHP) system is found to be superior to the gas engine driven heat pump (GHP) system for the energy consumption and cost-effectiveness due to its higher system efficiency. However, the result of social cost perspective shows the GHP system is superior to the EHP system considering incurred incremental electricity generation capacity construction cost and avoided gas storage tank construction cost due to a new installation of each system. And this paper suggests three analysis methodologies – the primary energy, final consumer, and social cost perspective – can be used for developing various measures and policies for integrated demand side management. [Copyright &y& Elsevier]

Abstract The world trade volume of Liquefied Natural Gas (LNG) is increasing year by year. Unlike gaseous natural gas (NG), which is transported through a fixed network of pipelines, LNG offers more flexibility to both the exporters and the importers as it can be transported between any pair of exporting and receiving LNG terminals. The LNG process, consisting of liquefaction, transportation, storage, and regasification of LNG, is accompanied by certain energy demands. The paper focuses on the evaluation of the chain of energy transformations involved in the LNG process. Based on the review of existing information, the entire process is evaluated from the view of the potential use of LNG for direct storage of cold and indirect storage of power. The analysis of the existing data shows that the overall efficiency of using LNG for operative energy storage depends very much on the technologies involved and on the overall capacity of the particular technology. The combination of energy-efficient liquefaction technologies and regasification technologies with energy recovery makes it possible to employ LNG as an energy storage medium even when transported over large distances. Graphical abstract fx1 Highlights • The chain of energy transformations involved in the LNG process was evaluated. • Liquefaction is the most energy demanding part of the LNG process. • There is a significant potential for the reduction of energy demand of liquefaction. • LNG potential as a thermal energy storage medium was explored. • Cold energy from the LNG can effectively be used in many applications. [ABSTRACT FROM AUTHOR]

Abstract: During the last three decades, a number of studies have been conducted by various investigators in the design, modeling and testing of earth to air heat exchanger (EAHE) systems. This paper reviews the studies conducted on the experimental and analytical analysis of EAHE systems in Turkey and around the world as of the end February 2011. The studies undertaken on the EAHE systems are categorized into two groups as follows: (i) open loop for space heating/cooling and (ii) closed loop for space heating/cooling systems. This paper investigates the studies on EAHEs, also known underground air tunnel systems. [Copyright &y& Elsevier]

Abstract: The electricity demand in Iran has increased steadily in recent years. This is mainly due to the rapid growth in the number of high-rise air-conditioned buildings and the rapid use of electrical appliances in residential and commercial sectors. This paper investigates the annual energy required for cooling per unit area and the total energy cost per unit area for each type of air conditioning systems in different climates in Iran. The paper also investigates the effects of changing the coefficient of performance (COP) of absorption chillers on cost saving. This study found that using absorption chillers for cooling will increase the amount of energy usage per unit area; however the energy cost per unit area will decrease. In addition this research indicates that for each 0.1 increment in COP of absorption chillers, there is at least 50USD/m2 saved cost. [Copyright &y& Elsevier]

Abstract: This paper presents the review of the development and application of the thermally activated desiccant cooling technologies. The paper first introduces the global problem of energy and the environment related to the consumption of the carbon-based energy sources (gas, oil and coal). The contribution of the building sector to the above problem so as to maintain indoor environment providing human thermal comfort is shown. In this paper, the alternative methods for the provision of the human thermal comfort through thermally activated desiccant cooling technologies are discussed—solid desiccant, liquid desiccant and hybrid desiccant cooling systems. These technologies are potential alternatives to the mechanical vapor compression cooling technologies in the provision of human thermal comfort conditions. However, the development and application is mostly in developed and advanced developing countries. For a global scale solution to the problem of energy and environment contributed by the building sector for maintenance of comfortable conditions, dissemination of ideas and technologies to the developing world (Africa, South and South East Asia, South America) enhances the applicability and practicability of these technologies. [Copyright &y& Elsevier]

Abstract: Geothermal energy pile foundations are an alternative energy source for heating and cooling needs. Utilising this source of energy has great potential due to the environmental, economic and social benefits. This paper looks at an extensive amount of literature on the technology behind the system including the overall process, primary considerations for each of the main components including latest developments as well as design implications such as the integration of ground energy systems into structural piles of buildings. Environmental considerations including performance-dependent parameters of the subsurface are described. Main parameters include thermal conductivity, thermal diffusivity, specific heat capacity and moisture content. Temperature and groundwater effects are also discussed and design considerations are provided. Mathematical models are available to aid in the design of these systems but there are various other issues and complex parameters that need to be considered qualitatively. Furthermore, the design of these systems is governed by various standards and government legislation. Case studies are presented to show the application of these systems in practise including assessments of system performance. Examples originate from countries such as Austria, Switzerland, Germany, UK, USA, Japan, Iran, Sweden and Norway. Benefits and limitations of implementing these systems are summarised and finally, the feasibility of geothermal energy pile foundations in Australia is explored. This paper found that these systems, although exhibiting some limitations and possible challenges, are a viable option in terms of an alternative energy source. [Copyright &y& Elsevier]

Abstract: A comprehensive review of various possible methods for heating and cooling in buildings are discussed in this paper. The thermal performance of various types of systems like PCM trombe wall, PCM wallboards, PCM shutters, PCM building blocks, air-based heating systems, floor heating, ceiling boards, etc., is presented in this paper. All systems have good potential for heating and cooling in building through phase change materials and also very beneficial to reduce the energy demand of the buildings. [Copyright &y& Elsevier]

Energy piles present a double function as bearing elements supporting the loads transferred by constructions and heat exchanger elements delivering the energy for heating and cooling. In comparison to conventional piles, they are subjected both to thermal and mechanical loadings, which affect their behaviour. Energy pile design also requires efficient and unambiguous approaches to provide the most appropriate verifications. Despite of their increasing implementation across Europe, some gaps are still present regarding their mechanical design; especially concerning the effects of the imposed cyclic thermal solicitation in the pile due to the successive periods of heating and cooling. Very few details can be found about the choice of the thermal solicitation that the designer has to consider for the design of an energy pile: number of cycles, cyclic thermal amplitude, influence of the thermal loading order, etc. In this objective, this paper includes the study of a single energy pile installed in saturated sandy soil affected by different combinations of thermal loadings. Based on the analysis of the pile displacements and the distribution of the axial forces, some recommendations are given to better appreciate the impacts of the choice of the imposed thermal solicitation in the pile. [ABSTRACT FROM AUTHOR]

Buildings contribute to climate change by consuming a considerable amount of energy to provide thermal comfort for occupants. Cooling energy demands are expected to increase substantially in the world. On this basis, technologies and techniques providing high energy efficiency in buildings such as passive cooling are highly appreciated. Passive cooling by means of phase change materials (PCM) offers high potential to decrease the cooling energy demand and to improve the indoor comfort condition. However, in order to be appropriately characterized and implemented into the building envelope, the PCM use should be numerically analyzed. Whole-building energy simulation tools can enhance the capability of the engineers and designers to analyze the thermal behavior of PCM-enhanced buildings. In this paper, an extensive review has been made, with regard to whole-building energy simulation for passive cooling, addressing the possibilities of applying different PCM-enhanced components into the building envelope and also the feasibility of PCM passive cooling system under different climate conditions. The application of PCM has not always been as energy beneficial as expected, and actually its effectiveness is highly dependent on the climatic condition, on the PCM melting temperature and on the occupants behavior. Therefore, energy simulation of passive PCM systems is found to be a single-objective or multi-objective optimization problem which requires appropriate mathematical models for energy and comfort assessment which should be further investigated. Moreover, further research is required to analyze the influence of natural night ventilation on the cooling performance of PCM. [ABSTRACT FROM AUTHOR]

District heating and cooling (DHC) systems are attracting increased interest for their low carbon potential. However, most DHC systems are not operating at the expected performance level. Optimization and Enhancement of DHC networks to reduce (a) fossil fuel consumption, CO2 emission, and heat losses across the network, while (b) increasing return on investment, form key challenges faced by decision makers in the fast developing energy landscape. While the academic literature is abundant of research based on field experiments, simulations, optimization strategies and algorithms etc., there is a lack of a comprehensive review that addresses the multi-faceted dimensions of the optimization and enhancement of DHC systems with a view to promote integration of smart grids, energy storage and increased share of renewable energy. The paper focuses on four areas: energy generation, energy distribution, heat substations, and terminal users, identifying state-of-the-art methods and solutions, while paving the way for future research. [ABSTRACT FROM AUTHOR]

A major portion of the total primary energy consumed by today’s buildings is used in heating, ventilating, and air-conditioning (HVAC). Conventional heating and cooling systems are having an impact on operational cost, energy requirement and carbon dioxide emission. In this regard, Trombe walls are receiving considerable attention because of their potential ability for addressing the environmental and energy crisis. This paper reviews the most pertinent contents of studies on Trombe walls that have been carried out in the recent 15 years. According to utilizing functions of Trombe walls, they are divided into two major types: a heating-based type and a cooling-based type. In terms of content, we emphasize the introduction of three groups of parameters that be considered when designing Trombe walls: the ‘Trombe wall’ parameters, the ‘building’ parameters and the ‘site’ parameters. Then different evaluation indicators on Trombe walls have been summarized from three points of view: energy, environment and economic. We hope that this review is useful to academic researchers and can provide a reference for architects or related engineering designers in the field of passive design. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilised to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. The performance improvements of TE devices have been mainly contributed by improved TE material research, TE device geometrical adjustments, design of integrated TE devices as well as the use of advanced TE mathematical models which have facilitated appropriate segmentation of TE modules using different materials. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electrical energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further. [ABSTRACT FROM AUTHOR]

Combined cooling, heating and power (CCHP) systems have the advantages of higher energy efficiency and lower economic and environmental impacts (3E) than separated systems. Recently, optimization methods have been extensively applied in CCHP system's design and control for further improving 3E performances of CCHP systems. However, a wide range of subsystems selection, nonlinear characteristics of subsystem models and uncertainty in modeling results of CCHP systems cause challenges for successful implementation of optimization studies at both design and control stage. This paper presents a systematic review of all aspects of optimization for CCHP systems from problem formulation and algorithms selection to technical implementation. Genetic algorithm, particle swarm optimization and differential evolution are the most common algorithms used in system optimum design and control. Optimization works in design stage focus on optimization of energy source, prime mover, storage system, energy demand and system configuration. Over 60% of renewable energy integrated CCHP system adopted solar energy. More investigations are needed for small scale prime mover and economic is the development obstacle among 3E objectives. Dynamic characteristics and mal-distribution problem should earn more attention when optimizing storage system in CCHP. For the system control aspects, the baseline control strategy of load-following method as well as optimum control under real-time data and uncertainty condition are discussed. The intermittent feature of renewable energy should be considered at system control stage with uncertainty study. Uncertainty inside of energy demands, subsystems performance and market price should be investigated at the same time during control stage. Overall, this review paper can be used as an optimization reference and guidance for optimum CCHP system design and control. • Comparison of different algorithms applied in CCHP system optimization. • Categorize research work based on the optimization stage. • Summarize CCHP system design optimization based on system configuration structure. • Differentiate CCHP system control optimization with considering real time data and uncertainty. [ABSTRACT FROM AUTHOR]

The urgency to look for promising sustainable alternatives to the conventional vapour compression technique for cooling applications has been strong. As the result, the gas-solid adsorption system has been considered as one of the alternatives to generate cooling effect. This paper reviews the development of this adsorption cooling technique in three different aspects: mathematical modelling, intrinsic, and extrinsic developments, in order to present an overview of this field from basic mathematical representations and designs to current research trends as well as innovative applications and configurations. Various adsorption equilibria, diffusion models, kinetics, and system modelling are reviewed. On the other hand, the roles of both the heat exchanger design parameters and the adsorbent materials are discussed followed by the different bed configurations and schemes. The impact of various operating parameters on the system performance is also covered. [ABSTRACT FROM AUTHOR]

Being a semi-arid country with limited fresh water resources and also a fossil fuel based energy intensive country, South Africa encounters the added pressure of allocating limited water resources. Roughly 90% of electricity in South Africa is generated from coal fired power plants that are located in semi-arid areas and use a combination of wet and dry cooling techniques. The paper aims to forecast water usage within coal based electricity generation in order to facilitate water management in water deficient parts of the country. Some of the older return to service (RTS) power plants which have been brought back to operation due to electricity shortages are water intensive and are located in water constrained water management areas. These power plants should be phased out gradually and replaced by higher efficiency dry cooled power plants - that are currently under construction – by the year 2020. Total water requirements could reach 370 gigalitres by the year 2021 from current levels of 360 gigalitres. Depending on the retirement of inefficient power plants, total water usage can be reduced by roughly 14%. Results show that management of water resources in the electricity generation sector can result in informed water allocations within water management areas. Proposed gradual retirement of the RTS fleet could result in a savings of 15% of the forecasted shortfall of 234 gigalitres by the year 2025. The deficit in electricity generation output caused by the retirement of the RTS fleet will have to be compensated by the simultaneous commissioning and operation of new build power plants. Such measures will provide much required water relief to water constrained water management areas. Overall increases in water usage until 2035 can be minimised if inefficient wet cooled power plants are gradually retired and if dry cooled power plants are more prominent. [ABSTRACT FROM AUTHOR]

Cogeneration is one of the methods to improve energy efficiency, reduce energy consumption and control environmental pollution. Downsizing the cogeneration system, improving its overall efficiency and incorporating it for meeting multiple objectives have been the topics of interest in the last three decades. A polygeneration system is a modified version of a cogeneration system, in which more than two objectives (i.e heat, power, cooling, production of energy or fuels) are achieved. This paper discusses the research and developmental activities that have been recently carried out in the area of trigeneration and polygeneration systems. [ABSTRACT FROM AUTHOR]

This paper focuses on the impact of sprinkling and refrigerant based cooling methods of photovoltaic modules on actual performance, the duration of cooling and the quickness of the impact of cooling in comparison with monocrystalline photovoltaic modules without cooling. The obtained findings were analysed both from technical and economic aspects. Based on the parameters of the regression model used in this study ( r =0.61), it can be concluded that a 1 °C increase of air temperature in the examined range (18–29 °C) improves actual performance by 1.58 W and cooling is probably necessary at higher temperatures. On more cloudy days, the expected performance is 9.8 W lower on average ( P =0.001). In both experiments, there was an obvious negative correlation between module temperature and actual performance under constant radiation conditions. On more sunny days, one unit change in temperature resulted in a performance change of 1.2–1.3% ( R 2 =0.87–0.95), while more cloudy days resulted in less close correlation and a much lower change of temperature (0.8–0.9%) ( R 2 =0.70–0.81). The following conclusions can be drawn in relation to the two examined cooling methods: • The actual performance of the sprinkling method is higher than that of the other two alternatives (by 19% and 25% in the case of the control method and by 13% and 18% in the case of refrigerant based cooling, depending on the day of measurement). • After deducting the electricity needed for sprinkling cooling, the electric performance was still 12% better on average, using 22.5 L water per day on average. In the case of the refrigerant based cooling method, the produced extra energy was less than the electricity need of the heat exchanger itself; therefore, this method obviously seems to be unviable both from energetic and economic aspects. [ABSTRACT FROM AUTHOR]

Solar photovoltaic (PV) is a commercially proven technology to generate electricity directly from the Sun. However, the major limitation of PV technology is its lower efficiency and higher cost as compared to conventional power generation techniques. These problems can be overcome by concentrating photovoltaic (CPV), which is the fastest growing technology due to its lower cost and higher electrical conversion efficiency (of about 40%). Nevertheless, with the increase in the concentration ratio (CR), the solar cell temperature increases, results in decrease in its efficiency and lifespan. This problem of rise in temperature can be overcome by using a proper cooling technology. In this paper review work of various cooling technologies available for CPV systems has been presented. Cooling technology should be reliable, maintain low and uniform cell temperature, easy to operate and efficient in nature. [ABSTRACT FROM AUTHOR]

Generally, the commercial and industrial electronic devices are required to be operated under 100 °C.Therefore, there is a need to remove heat effectively from these devices under different loading conditions. Till now, Phase Change Material (PCM) based heat sinks are emerging as one of the effective techniques for removal of heat from the electronic devices. However, the low thermal conductivity of PCM situates a hindrance to the development. Thus, current research focuses on improving the thermal performance of PCM using thermal conductivity enhancer (TCE). At present internal fins, metallic foams and nano particles are mixed with PCM to enhance the performance of heat sinks. These are called as thermal conductivity enhancers. This article reviews methodologically various papers on the methods used for enhancement of PCM performance in cooling of electronic components. The effect of various parameters influencing the performance of the TCE-PCM based heat sinks are discussed in systematic order. The performance of these heat sinks under constant and variable thermal load are also evaluated. Out of these three TCE, metallic foams in heat sinks provides a higher surface area to volume ratio, good thermal conductivity and considerable weight advantage. [ABSTRACT FROM AUTHOR]

Nowadays, one of the major challenges for administrations and governments is energy demand to satisfy thermal comfort in the buildings. In energy systems where a temporal difference exists between the supply of energy and its utilization, thermal energy storage is necessary to ensure the continuity of a thermal process. The development of thermal energy storage systems has been under consideration for a variety of applications such as solar thermal energy storage, waste heat recovery, free cooling, etc. Free cooling night ventilation is the process of storing the coolness in the night time and releasing this coolness in hot day time. Free cooling has attracted considerable attention in the last few years. Supreme efforts have been put into finding new powerful free cooling systems and quantifying their economic and technical feasibility for thermal comfort in buildings. This paper presents a review of studies focused on the free cooling application in the residential and commercial buildings. Many considerations have been highlighted in this review including the merits, demerits and limitations of the free cooling systems for buildings application. The application of phase change materials (PCMs) in the free cooling, thermal enhancement techniques, technical, geographical and economical aspects and their performance evaluation criteria have also been reviewed. A few studies that reported in the literature for the numerical modeling of PCMs have also been discussed and therefore this overview stresses the need to discuss numerical modeling of free cooling deeply. [ABSTRACT FROM AUTHOR]

Cooling of PV panels is a critical issue in the design and operation of concentrated photovoltaic (CPV) technology. Due to high cell temperature and non-uniform temperature distribution, current mismatching problem and hot spot occurs on the cell resulting in either reduction of efficiency or permanent structural damage due to thermal stresses. Temperature non-uniformity on the surface of PV panel has a major impact on the performance of CPV systems and directly increases cell temperature and series resistance. This review paper highlights the importance of uniform PV cooling by exploring the possible causes and effects of non-uniformity. Cooling techniques with low average cell temperature and uniform temperature distribution are analyzed. Economic and environmental impact on the importance of cooling of PV systems are discussed and an experimental case study is presented for comparison between uniform and non-uniform cooling methods. Immersion cooling is a promising solution for uniform cooling and has been reported to reduce the cell temperature to 20–45 °C for CPV systems. Heat pipes reduced the temperature down to 32 °C with the best case temperature non-uniformity of 3 °C. Passive cooling by heat sinks was found to reduce the cell temperature as low as 37 °C for high concentrations but with an expense of large heat sink area. Active cooling by microchannels, impingement cooling and hybrid microchannel-impingement cooling were found to be most effective in dissipating high heat flux from PV surface. Cell temperature was reported to decrease to 30 °C for 200× CPV using impingement cooling. For hybrid cooling, deviation of 0.46 °C surface temperature was obtained. Using PCM materials temperature of panel was controlled within 28–65 °C whereas optimization of heat exchanger designs also showed low and uniform temperature across surface. The impact of non-uniformity was found to be significant for all PV systems however the effect is more pronounced in CPV systems. [ABSTRACT FROM AUTHOR]

District cooling system (DCS) has been widely used because of its low cost and high energy efficiency. Excessive studies have been done on DCSs, based on either actual projects or hypothesis. This paper presents a comprehensive review on the research and applications of DCSs. The characteristics and problems of DCS are introduced. The performance and progress of DCS integrated with sustainable energy technologies are summarized, including systems integrated with renewable energy systems, combined cooling, heating and power systems, and thermal storage systems. Efforts on the optimization of DCS are reviewed and categorized, including the efforts on district planning, DCS design, operation and control. An introduction on the existing typical DCS projects in China is presented. Challenges and opportunities for future application of DCS are discussed including the uncertainty issues at design stage, the control optimization and integration with smart gird. [ABSTRACT FROM AUTHOR]

Chlorofluorocarbon and hydrochlorofluorocarbon refrigerants have been widely used in traditional cooling systems. These refrigerants accelerate the depletion of the Earth’s ozone layer. Therefore, adsorption air-conditioning technology attracted much attention recently as an alternative solution due to its advantage of environmental friendliness. This system as it powered by waste and/or solar heat can help to reduce required energy and thermal pollution. This paper presents an overview of research which have been carried out on adsorption cooling systems powered by waste heat from automobiles. Many adsorption pairs have been studied. Zeolite–water as a working adsorption pair has been widely used in automobile adsorption cooling systems. This pair has been powered by exhaust gases from the engine due to its relatively high working temperature. Silica gel–water pair has been also widely used in automobile adsorption cooling systems. It has been powered by waste heat from water coolant in the engine due to its relatively low working temperature. Results show that this technology can help in increasing overall engine efficiency and reduce thermal pollution from engines. Various modifications in adsorption cooling systems are still required. One of the bottlenecks which prevents the improvement of adsorption cooling technology is its relatively low performance compared to conventional vapor mechanical compression technologies. [ABSTRACT FROM AUTHOR]

This paper carried out a review study into the brick wall cooler storage system (zero energy storage) in terms of its originality, current status, research and implementation achievement, benefit and possible barriers. The continuous progress in technology innovation, heat and mass exchanger of the brick wall cooler storage system now varied from sand–zeolite mixture, volcanic plate made wall, natural ventilation for releasing excess inside relative humidity, optimization of watering operation to save water and successful integration of the solar-driven adsorption cooling system with brick wall cooler storage system enhanced the cooling performance over those the decade ago by increasing the shelf-life of the stored fruit and vegetables. This review work indicated that the brick wall cooler storage system has potential to be an alternative to conventional electric powered expensive cooling storage for fruit and vegetables in the rural areas of the developing world. Future success on the dissemination of brick wall cooler storage system towards farmer׳s community may imply on more study on newer type of low cost heat exchanger material; further study on its economic, environment and social impacts; low cost postharvest treatment and packaging for brick wall cooler storage system; extensive farmers awareness and other dissemination measures; and public awareness and other dissemination measures. [ABSTRACT FROM AUTHOR]

The use of ground coupled heat exchanger (GCHE) systems is increasing worldwide. They are mainly used for space conditioning, water heating, agricultural drying, bathing, swimming, etc. They reduce cooling load in summer and heating load in winter. GCHE systems make available excellent scope to conserve significant amount of primary energy and thus mitigating the impact on environment through emission reduction. This paper reviews the experimental and modeling studies carried out on GCHE systems. The reviewed literature focuses on performance of both types of GCHE systems viz. earth–air heat exchanger (EAHE) and ground source heat pump (GSHP) systems and brings out their merits and demerits. [ABSTRACT FROM AUTHOR]

This paper presents a review of the available technologies to provide cooling from solar energy for both thermal and photovoltaic ways. Several multi-criteria performance indicators figuring in the literature are presented followed by a pros and cons analysis of the different solar thermal cooling processes. A market study is also carried out to evidence the potential of these solar cooling technologies. Finally, an overview of various solar cooling installations in Europe, Egypt and China is presented. [ABSTRACT FROM AUTHOR]

This article highlights a method for natural heating and cooling of systems in areas of moderate climate. Movement of air is generated in the system by an underground piping system. In this paper, we discuss a feasibility study in Algeria of air-conditioning using a ground source heat pump (GSHP) with vertical mounting, coupled with a solar collector. This study consists of modeling ground temperature at different depths, for a clay soil in the city of Tlemcen. Our model is developed from the non-stationary heat equation for a homogeneous medium and takes into consideration the soil thermal diffusivity. It uses the daily ambient temperature during a typical year for the locality of Tlemcen. The study shows the feasibility of using a heating/cooling GSHP in the town of Tlemcen for the particular soil type, and indicates that the duration of air flow in the borehole has a major influence on the outgoing temperature drilling. [ABSTRACT FROM AUTHOR]

In this paper the authors review 25 original Small and Medium sized Reactor designs currently under development, licensing procedure or in operation. Technology overview, safety features and ability to mitigate proliferation are considered. In order to show common research trends and highlight the features of particular designs the authors choose to classify the reactors according to used technology and cooling medium. The main requirement for a new reactor design is to secure inherent and passive safety features, thus different ways to achieve it are shown. The Pressurized Water Reactor (PWR) is the most advanced and most commonly used technology. In PWR, passiveness and inherency of safety features are ensured by integrating steam generators inside the Reactor Pressure Vessel (RPV). It eliminates possibility of Loss of Cooling Accident (LOCA); moreover the technology allows swift removal of heat produced during normal or accidental conditions. Heavy Water Reactors (HWRs) are also in operation, however, the design process of improving emergency cooling system is ongoing. The design of Supercritical Water Reactor (SCWR) based on Canadian HWR is reviewed including the ongoing development in novel leakage detection method and material improvement. Liquid Metal Cooled Reactors (LMCR) are in advanced stage of research and development focusing on lead and sodium as the coolants. LMCR are secured from LOCA accidents due to low operating pressure and integration of the most elements in RPV. In case of Advanced Gas-Cooled Reactors (AGCR) the literature indicates several possible system integrations related to high operating temperature under development. AGCRs are able to use fully passive systems during all events due to their low power density. Furthermore, it is noted that the use of innovative reactor designs can mitigate proliferation concerns to an acceptable level. The authors identify the common research trend among all designs as the fuel cycle evaluation and optimization. [ABSTRACT FROM AUTHOR]

In this paper, a brief overview of different available and actually installed solar thermal driven technologies used for cooling or air-conditioning purposes have been presented. A review analysis has been performed taking into account research on experimental and simulated solar cooling systems in terms of COP, area of collector ( A c ) per unit chiller capacity ( P ch ) and volume of storage tank ( V ) per unit area of collector. The COP of absorption chillers lies between 0.6 and 0.8 for simulated and 0.40–0.85 for experimental systems for generator inlet temperature between 70 and 100 °C with dominance in the market. Adsorption chillers have lower COP in the range of 0.2–0.6 both for simulated and experimental systems. However, adsorption chillers can work at lower generator inlet temperatures in the range of 45–65 °C. The ratio of A c to P ch presents a wide spread ranging from 1.5 to 11.5 m 2 kW ch −1 . It shows that some installation may have additional area of collector installed resulting in higher thermal energy losses and initial cost of the system while others may have lower A c installed resulting in lower solar fraction and lesser primary energy savings. Similarly, the ratio of V to A c also shows a large variation in both simulated and experimental systems ranging from 5 to 130 l m −2 . However, most of these systems lie in the range of 20–80 l m −2 . The range of storage volume is suggested between 50 and 110 l m −2 but at a first glance it seems that keeping fixed storage volume linked to area of collector may not be an economical solution for large collector areas. Although these installations are designed for solar cooling/air-conditioning purposes only but utilization of these installations further for space heating and sanitary hot water production so called multi-purpose solar thermal systems (MPSTS) will provide better results of primary energy savings. [ABSTRACT FROM AUTHOR]

With the increase in electronic traffic, heat generated by electronic equipment, and the concomitant costs of powering cooling systems in electronic data centers are increasing continually. Various research groups working in academic institutions, research laboratories and industries have been applying a variety of tools to study and improve performance of data centers. This paper reviews recent contributions to the state of knowledge in data center thermal management. First, we review numerical and experimental studies on the most common air-cooled raised floor plenum type data centers. We then summarize published research on rack layout, efficiency and performance metrics for data centers, dynamic control and life cycle analyses, and validation of numerical models. Finally, we review some recently proposed cooling strategies and numerical optimization efforts. We find that the research carried out on thermal management of data centers has helped improve performance in many instances (such as rear door water cooled heat exchanger type rack), and has helped establish some physics-based criteria for data center designers. Based on the trends observed in this review, we expect further improvements to all aspects of data center design and operation in the near future, with a focus on real-time measurement & control, model validation and heuristics based optimization. In addition, some significant changes such as thermal energy storage and smart-grid capabilities are also expected to be incorporated into data center control strategies. [ABSTRACT FROM AUTHOR]

The efficiency of wafer-based crystalline as well as Thin film Solar photovoltaic cells get reduced with increase of panel temperature. It is noted that the efficiency drops by about 0.5% for increase of 1 °C of panel temperature. It is necessary to operate them at low temperatures in order to keep the PV module electrical efficiency at acceptable level. Therefore need for a low-cost cooling system for the Solar panels is felt. The cooling of Solar PV panels is a problem of great practical significance. It has the potential to reduce the cost of solar energy in three ways. First, cooling can improve the electrical production of standard flat plate PV modules. Second, cooling makes possible the use of concentrating PV systems. Finally, the heat removed by the PV cooling system can be used for domestic or industrial use. Various Solar PV panel cooling systems have been developed in past. A new system for cooling of Solar PV panels called the Ground-Coupled Central Panel Cooling System (GC-CPCS) is installed and operational at the Energy Park of Rajiv Gandhi Proudyogiki Vishwavidyalaya (RGPV), Bhopal, India. This paper discusses various Solar PV panel cooling technologies and the testing and performance of the newly developed Ground-Coupled Central Panel Cooling System (GC-CPCS). This study is unique in three ways. First, it introduces the concept of Central cooling of Solar PV panels. Second, Ground Coupled Heat Exchanger is used for the first time in any Solar PV Panel Cooling System. Third, the testing is done on site under actual solar irradiance. [ABSTRACT FROM AUTHOR]

Thermal Energy Storage (TES) has been a topic of research for quite some time and has proven to be a technology that can have positive effects on the energy efficiency of a building by contributing to an increased share of renewable energy and/or reduction in energy demand or peak loads for both heating and cooling. There are many TES technologies available, both commercial and emerging, and the amount of published literature on the subject is considerable. Literature discussing the combination of thermal energy storage with buildings is however lacking and it is therefore not an easy task to decide which type of TES to use in a certain building. The goal of this paper is to give a comprehensive review of a wide variety of TES technologies, with a clear focus on the combination of storage technology and building type. The results show many promising TES technologies, both for residential and commercial buildings, but also that much research still is required, especially in the fields of phase change materials and thermochemical storage. [ABSTRACT FROM AUTHOR]

Rotary desiccant wheel cooling system operates on the principle of adsorption dehumidification and evaporative cooling. The system adopts natural substance as working fluid and can be driven by low grade thermal energy such as solar energy. Due to these merits, solar powered rotary desiccant wheel cooling system has recognized as one of good alternatives to conventional vapor compression air conditioning system and has obtained increasing interests in the past years. This paper aims to summarize recent research developments related to solar powered rotary desiccant wheel cooling system and to provide information for potential application. Based on whether auxiliary refrigeration system is adopted, the systems are divided in to two categories: separate solar powered rotary desiccant wheel cooling systems and hybrid solar powered rotary desiccant wheel cooling systems. Within the first category, separate solar powered rotary desiccant wheel cooling systems are reviewed according to different types of solar collector. It can be found that these researches mainly focus on feasibility study of such system under different climates. Results show that separate solar powered rotary desiccant wheel cooling systems can be adopted in several representative cities in Europe, Asia, Australia and Africa. However, system performance in terms of solar fraction and thermal coefficient of performance varies greatly with respect to different operation conditions. For the second category, works related to hybrid solar powered rotary desiccant wheel cooling systems are grouped by types of auxiliary refrigeration systems. It can be found that vapor compression system is widely adopted in these hybrid systems. Also, due to both solar energy and electricity are consumed in hybrid systems, primary energy consumption is an important performance index. Results show that hybrid solar powered rotary desiccant wheel cooling system can obtain significant energy saving compared with conventional vapor compression system. [ABSTRACT FROM AUTHOR]

Abstract: The building industry nowadays is facing two major challenges – the increased concern for energy reduction and the growing need for comfort improvements. These challenges have led many researchers to develop a personalized conditioning system. Personalized conditioning aims to create a microclimate zone around a single workplace. In this way the energy is deployed only where it is actually needed, and the individual needs for thermal comfort are fulfilled. In recent years personalized conditioning has received a lot of attention in research publications. This paper reviews the impact of different personalized conditioning systems on thermal comfort and building energy performance. In the reviewed publications, it was demonstrated that thermal comfort can be well maintained at ambient temperatures that are 4–5K higher as well as lower than the temperatures recommended by current standards. Personalized conditioning also allows reduction in energy consumption due to an increased cooling setpoint, a decreased heating setpoint, or a decreased ventilation rate of the background system. Energy simulations show that reductions of up to 60% can be achieved. [Copyright &y& Elsevier]