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The amount of energy expenditure in buildings is 30–40% of the total energy consumption in the world and this share will increase to 50% by 2050. Therefore, reducing energy consumption is a necessity and one of the ways to reduce energy expenditure in buildings is to use passive methods. The use of DSF is expanding as a new approach for building facades due to its ability to prevent excessive heat by absorbing solar radiation. For this purpose, the energy performance of PCM and DSF was studied in three climates of Tehran, Tabriz, and Kish Island, to reveal their energy saving potential. Based on the results of this article, the use of PCM in different layers of DFS can result in a considerable energy saving in Iran residential sector. PCM is integrated both in the external wall and in the partition wall of the DoubleSkin Façade under three different climates. DesignBuilder is used for the thermal analysis of the building. The effects of melting temperature, location of PCM layer in the wall have been investigated. The results showed that we will witness the highest total energy savings percentage in the cold semi-arid climate because of using Infinite RPCM23 in October, amounting to 91.6%. In addition, by using Infinite RPCM25 in warm semi-arid climates in the highest percentage of heating load savings is 99.9% in December and January, and the highest percentage of cooling load savings in cold semi-arid climates is 67.5% by using InfiniteRPCM23 in September. [ABSTRACT FROM AUTHOR]

The utilization of phase change materials (PCMs) in buildings leads to the reduction of energy consumption and maintaining the indoor temperature within the comfort range. The PCM performance strongly depends on the climatic conditions, causing a major challenge. To overcome this issue, the employment of a double-layer PCM system is introduced. The energy and economic assessments of various double PCM systems in the building located in different climatic conditions of Iran have been conducted for the first time. In this study, two PCM wallboards with different enthalpy and melting temperatures were embedded in the external walls of a residential building located in various climatic regions of Iran. The performance of the double-layer PCM system in five cities of Iran including Tehran, Isfahan, Shiraz, Tabriz, and Bandar Abbas during hot and cold months of the year was evaluated from energy and economic viewpoints. It was inferred that embedding a double-layer PCM system reduces the heating/cooling energy consumption compared to single-layer ones. It was concluded that the RT18/RT28 double PCM system was the best candidate to be employed in the external walls of the building located in Tehran and Shiraz, which reduced the total energy consumption of the building up to 6.26% and 5.17%. The RT18/RT22 double PCM system was the most efficient system for the building placed in Tabriz and Isfahan reducing the total energy consumption up to 4.41% and 3.87%, and the RT22/RT28 double PCM system had the best performance in the building located in Bandar Abbas, which could save 6.58% of total energy. Moreover, it was concluded that the use of a double PCM system reduced temperature fluctuations in the external walls. In addition, the economic analysis was performed using the dynamic payback period and the results revealed that the employment of a double-layer PCM system reduced the investment return period by up to 50%. [ABSTRACT FROM AUTHOR]

Buildings consume around 32% of the produced energy, worldwide and around 19% of the greenhouse gas emissions are related to them. It makes the buildings one of the largest energy consumers and one of the major sources of greenhouse gases emission. HVAC systems are one of the largest consumers of energy in buildings. In hot arid climates, cooling systems used in buildings impose a large pressure on the power grid, which may lead into blackouts. In order to address this problem, several approaches have been examined. Thermal energy storage, in particular, latent heat storage using phase change materials (PCM) has been notably considered in construction applications because of high energy storage densities. In this paper, the effect of using PCMs on energy consumption and peak load demand of a sample building is studied. Besides, impacts of precooling as a peak load shifting strategy is also investigated in presence of PCMs on the energy consumption of the sample building. The study was carried out for the weather condition of Kerman, Iran and the simulation is performed by TRNSYS software. Three types of phase change materials were investigated for two different scenarios. The simulation was performed at two stages and two modes for each stage which each mode had its own set point temperature. The application of PCMs was considered at the first stage and precooling added to the simulation at the second stage. The results of the first stage showed that employing PCMs in the studied building reduces the cooling load up to 13%. With precooling, the cooling load reduction was up to 16%. At all stages peak loads decreased with maximum 14% at the first stage and 42.5% at the second stage. It has been showed that the solid–liquid phase change temperature of the PCMs close to the selected room temperature, have significant impact on the performance of PCMs for reducing the energy consumption of the sample building compared to the other thermal properties. Due to the low electricity prices in Iran, despite the high amounts in load reduction achieved by each strategy, the cost savings during hot months of the year was not significant. [ABSTRACT FROM AUTHOR]

Researchers have proposed and studied many methods to reduce energy consumption in the construction sector. However, simultaneous use of phase‐change material (PCM) and green roofs in a building with double‐ or triple‐skin facades (DSF or TSF) has not been analyzed to date. Accordingly, this is the first study to evaluate and compare the design of two scenarios combining passive and active methods, including (1) simultaneous use of a DSF, PCM, green roof, and photovoltaics (PV), and (2) simultaneous use of a TSF, PCM, green roof, and PV in hot arid steppe‐dry mid‐latitude (Tehran) desert biome‐dry tropical (Yazd), and mild‐humid climate (Amol) in Iran. It was found that the first scenario works better in reducing the heating load and the second scenario is more effective in reducing the cooling load. The results indicate that the reduction of the annual heating load in the first scenario was 49, 45.1, and 40.7 MWh/year in Tehran, Yazd, and Amol, respectively, and that the reduction of cooling load in the second scenario was 48.4, 31.9, and 16 MWh/year in Yazd, Tehran, and Amol, respectively. The 14 different modes of combining these passive methods and PV system were then compared. The results indicate that the second proposed scenario caused the lowest annual energy consumption compared to that of other modes and saved 70% of annual energy consumption. Consequently, the effect of leaf area index, cavity width, and orientation that are selected as primary parameters affecting the thermal performance of the mentioned methods on this scenario were investigated. [ABSTRACT FROM AUTHOR]

Selection of the optimum values for net zero energy buildings (NZEB) is a complex task, due to the existence of multiple objectives. In the current study, cold and semi-arid climate was considered for investigation, and DesignBuilder was used for simulating a residential NZEB in Shiraz, Iran, as a case study. First, optimum solutions for minimising the cooling and heating demands were obtained by obtaining a Pareto front including 21 points. Then, phase changing materials (PCMs) were integrated to the envelope to further optimise energy consumption. The obtained results illustrated that using PCMs on both sides of the envelope can significantly reduce the energy consumption. Findings of this study are beneficial for the future plans of Iran, particularly with regards to improving sustainability within the building sector. • Integration of multi-objective optimisation algorithm with dynamic simulation tool. • Discussion of design criteria for residential NZEB in semi-arid climate. • Minimisation of energy demand by considering discomfort as constraint. • Discussion on innovative configurations of novel passive strategies. [ABSTRACT FROM AUTHOR]

In the present study, a five‐stage solar still is investigated in which paraffin wax was considered as the phase change material. Considering the climatic conditions of Iran and its locating in an arid area and shortage of freshwater resources, it is essential to produce freshwater from saline water resources. So, herein, a multi‐stage solar still as a commonly used water desalination apparatus with paraffin wax phase change materials was designed, fabricated, and tested. On the back of the collector absorber, the paraffin wax was applied for storing the additional solar energy. The results showed that the application of paraffin‐wax phase‐change agent leads to a 15% increase in freshwater production. The quantity of water generated was also studied in the flow rates of 0.7, 1.3, and 1.8 L/min with and without phase change materials. The results showed that the highest quantity of water produced is obtained in the 1.3 L/min flow rate. Finally, the quantity of water generated in the five stages of the desalination process was separately measured and found that the water produced in the first stage was 70% of the total water. [ABSTRACT FROM AUTHOR]

Summary: In the present experimental research, a five‐stage solar still was investigated using phase change material paraffin wax. Owing to Iran's climatic conditions and its location in a dry area and nonexistence of fresh water sources, producing this water from saline water sources is essential. In this research, thus, a multistage solar still was planned and examined as a commonly used freshwater source via (phase change material) paraffin wax. On the back of the collector absorber plate, paraffin wax (phase change material) was used as an additional energy source for the sun. The volume of water produced in different thicknesses of 2.5 cm, 5 cm, and without PCM was investigated. The study results specified that the application of phase change material paraffin wax in the thickness of 2.5 cm agent led to a 15% increase in freshwater production. The quantity of water generated in the flow rates of 0.7, 1.3, and 1.8 L/min was also studied. The highest quantity of water produced was obtained in the 1.3 L/min flow rate. Moreover, the quantity of water generated in the five stages of the desalination process was separately measured that the highest amount of production was associated with the first stage. [ABSTRACT FROM AUTHOR]

In order to attain an efficient path into the enhancement of the sustainable conservation and management of energy resources in the buildings and residential sections, efforts by all relevant institutions in the area of energy are essential and primitive. Hence, the development of the energy supply model in the building and the provision of fundamental solutions in this area is rudimentary. The key to any program related to this matter is to boost and extend energy efficiency and energy resource management. According to the global statistics and processed data, the residential sector accounts for 34 percent of the total energy consumption in Iran, which is the highest energy consumption compared to all existing sectors; therefore, immeasurable research has been done on optimizing energy usage in the building sector. One of the most efficient energy optimization methods can be achieved by using energy storage materials in the outer walls of the buildings. In this project, a research‐based residential building is considered as a case to investigate for energy optimization. In the first stage, the building is simulated and the energy consumption of the building is measured. Afterward, with actual measurements, real consumption is approximated and compared with the results of the software. After verifying the software data, the insulation is simulated in the software and the outcomes of using this insulator are investigated to reduce energy consumption. Energy storage materials are considered as a type of phase‐change material. These materials have the same characteristics which is having a different melting point and, by capturing and losing heat at design temperatures, they can help maintain energy inside the building that is how they can be considered as an insulator. Within the appropriate software which is Design‐Builder, miscellaneous types of these materials are available with various features. The final results point out that the use of this material saves up to 30% of the heating energy and about 8% in the cooling load of the building. [ABSTRACT FROM AUTHOR]

• The presence of PCMs reduces temperature fluctuations and heat transfer to the room. • Performing sensitivity analysis for HTR based on variation in properties. • Thermal conductivity of PCM plays most significant role in selecting the appropriate PCM. • For equal thermal conductivity, closer melting point to room temperature is preferred. • When PCM is closer to the exterior, a larger portion of it melts, HTR is greater. Passive latent heat thermal energy storage approach incorporating phase change materials (PCM) is a brilliant technique to tackle high energy consumption issue in buildings. This paper investigated the thermal performance of the conventional walls of buildings in Isfahan, Iran with the inclusion of thirteen different phase change materials. The studied base wall was composed of plaster (2 cm), clay brick (15 cm), and cement (3 cm). The effect of PCM position inside the wall on the heat transfer was assessed in two scenarios, namely: close to the interior and close to exterior. The nonlinear governing equations were solved using the finite volume method. The results show that the performance of PCM-based wall is strongly influenced by the thermal conductivity, phase-change enthalpy and melting temperature of PCM. A PCM can more efficiently reduce the heat transfer to the interior space in case it has a lower thermal conductivity, has a higher latent heat of phase-change, and its phase-change temperature is closer to the room temperature. Moreover, the thermal conductivity has priority over other PCM thermophysical properties. The lower PCM thermal conductivity leads to transfer the lower amount of heat to the interior space. A two-fold increase in the thickness of the PCM leads to less than a twofold reduction in the heat transfer. Among the studied PCMs, the heat transfer reduction by Enerciel 22 was within the range 15.6–47.6%, while this range was 2–7.8% for CaC l 2. 6 H 2 O. [ABSTRACT FROM AUTHOR]

In this study, a series of experimental runs performed under different conditions in order to evaluate the effectiveness of a household refrigerator. Two eutectic phase change materials (PCMs) arranged in a cascade configuration have been tested on the performance of the system. The PCMs were placed on the back-side of the wire-and-tube condenser in a decreasing order of their melting temperatures along the refrigerant flow direction to achieve a high heat transfer rate and to reduce energy consumption. The operating characteristics of the novel refrigerator were studied and compared with the results of a refrigerator equipped with a single PCM and two ordinary refrigerators with and without measurement packages (M-packs). All the tests have been performed in standard condition in Philver Company in Tehran, Iran. For the novel refrigerator, the temperature of the condenser surface significantly decreased, which led to a lower condensing temperature during the refrigeration cycle and improved the coefficient of performance (COP). Also, the ratio of the on-time to the total experiment time was considerably shorter compared to the refrigerator equipped with a single PCM and two ordinary refrigerators. According to the results, integration of two different PCMs on the condenser surface in a cascade arrangement decreases the compressor work time percentage from 32.7 to 27.6, while this parameter was decreased to 29.6 with a single PCM. Finally, the energy consumption was reduced by 13% in the novel refrigerator whereas it was only reduced by 8% in the refrigerator equipped with a single PCM. • Efficiency enhancement of a household refrigerator has been studied. • Eutectic phase change materials with cascade configuration have been used in the system. • The compressor off-time of the novel system lowered significantly. • Energy consumption of the refrigerator with single PCM was reduced by 8%. • Further energy consumption reduction up to 13% has been achieved in cascade configuration. [ABSTRACT FROM AUTHOR]

Properties of desirable weight, latent heat capacity, and energy storage capability of phase change materials (PCMs) have led to extensive use of these materials in the building industry as productive thermal mass. This study investigated the feasibility of the utilization of PCMs through numerical simulations in residential buildings located in different Iranian climates in Tehran, Tabriz, Yazd, and Bandar Abbas. In so doing, the optimal PCM for each city was selected based on its impact on annual energy consumption, and then its effects on the indoor temperature and thermal load of the model in the hottest and coldest months of the year were examined. The results showed that the use of PCMs does not lead to significant energy conservation in the hot and humid climate of Bandar Abbas compared with other climates. In the second part of the study, the economic feasibility of PCMs and the payback period of such investment were investigated based on the current local electricity and natural gas prices. It was found that although the use of PCMs leads to significant energy conservation in most of these climates, with the current prices of energy and PCMs in Iran, the use of these materials will not be cost-effective, as the return periods for such investment in Tehran, Tabriz, Yazd, and Bandar Abbas will be 42, 179, 102, and 114 years, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a solar absorption chiller used in MehrAbad region of Tehran, Iran is optimized with exergoeconomic principles and genetic algorithm. After optimizing, a storage system with Phase Change Material technique (PCM) is designed for this optimum configuration for supporting system when sunshine is not received adequately, especially at night. Exergoeconomic analysis is based on finding some ways to improving the performance of a thermal system considering economic constrains. In this study, the exergoeconomic optimization is applied for LiBr–water absorption. The results show that total investment cost of main system, the whole of system except storage system, has increased 2.0568% rather than the base case that system usually operates. With adding storage system to main system in optimum point, pay back period increases from 0.61 years to 1.13 years. [Copyright &y& Elsevier]

• The SSPCM was employed to prepare cement mortars for plastering masonry brick walls. • An experimental setup was utilized to perform thermal performance test on the wall specimens. • The wall specimens were under ambient temperature conditions of two different cities of Iran. • The physical and mechanical properties of SSPCM-incorporated mortars were measured and analyzed. • The developed SSPCM incorporated in plaster mortar provides thermal energy storage capability. Phase change materials (PCMs) have been widely proven to provide thermal energy storage (TES) capacity in building systems. However, some potential problems associated with the incorporation of PCMs in building materials may cause uncertainty about their real performance. Among such problems, the leakage possibility of PCMs in the molten state has been greatly addressed in the literature. In this regard, this study is aimed to evaluate the mechanical and thermal behavior of a shape-stabilized PCM (SSPCM) as a TES component in the conventional wall system of buildings in Iran. For this purpose, PEG 600 was shape-stabilized in the porous structure of the silica fume as the supporting material using the vacuum impregnation method. The SSPCM was further employed to prepare cement mortars for plastering masonry brick wall specimens. The mechanical experiments on the SSPCM-incorporated mortars indicated satisfactory results to be used as the finishing plaster for masonry walls. Moreover, a novel experimental setup was utilized to perform thermal performance test on the wall specimens plastered with SSPCM-incorporated mortar under ambient temperature conditions of two different cities. Accordingly, the developed SSPCM exhibited the promising potential to provide TES capacity in external masonry wall systems by reducing the peak temperature as well as mitigating indoor temperature fluctuations. [ABSTRACT FROM AUTHOR]

One of the most common issues associated with wind energy penetration as a viable resource is high instability under diverse amplitudes and frequencies. Compressed air storage systems (CAES) and thermal energy storages (TES) not only are promising alternative solution for renewable resources generally, but they are also used with the aim of peak shaving to provide cleaner and affordable power. Due to high storage density with low temperature gradient between storing and retrieving in comparison with sensible heat storage, phase change material (PCM) is selected considering their thermophysical properties. This work, presents a recovery approach by using PCM during 12 h' compression periods to retrieve it in 12 h' expansion as a case study in November for Baladeh (a city in north of Iran). It is worthy to mention that, in order to use PCM in multiple mentioned stages, auxiliary heaters facilitate system to provide constant heat load in each used stage. This concludes system to be more efficient, sustainable and can reduce irreversibilities. Temperature of PCMs and amount of heat stored and released versus time are modeled. A good agreement between PCM model and reported results of related articles was seen. Following to the energy and exergy balances calculation, round-trip efficiency (RTE) and total exergy efficiency of system, reach 70.83%, 80.71%. Exergy analysis showed that near 60% exergy destruction occurred in PCMs with major contribution of second ones in both charge and discharge times. Sensitivity analysis is also investigated assuming the effect of number of wind turbines which shows a reduction in RTE, steeper slope in increasing TES volume for PCM3 and amount of heat stored, by increasing them. Image 10372 • A hybrid renewable energy storage system using phase change materials is investigated. • Compressed air storage and thermal energy storage methods are integrated. • RTE and total exergy efficiency of the system, reach 70.83%, 80.71%. • A city in north of Iran is considered for design of wind farm integrated to the energy system. [ABSTRACT FROM AUTHOR]

• An integrated system is proposed to produce power, cooling, and freshwater. • Novel Thermal Energy Storage (TES) is suggested using phase change material (PCM). • Using high temperature PCM for TES, continuous operation of system is feasible. • The overall energy and exergy efficiencies are 40.52% and 14.40%, respectively. • The LCoE of the plant follows the downward trend of concentrated solar plants. In this article, three different modes of a novel integrated system would be evaluated by the application of high temperature Thermal Energy Storage (TES) to produce electricity, cooling, and freshwater. Freshwater is produced using the reverse osmosis (RO) desalination unit while Absorption Refrigeration Cycle (ARC) provides cooling. In this system, a high temperature Phase Change Material (PCM) is utilized to make the system working continuously even at nights. The output heat of gas turbine (GT) is also recovered utilizing the Organic Rankine Cycle (ORC). According to exergoeconomic analysis, the efficiencies, exergy destructions and product cost rates are computed. The multi-objective optimization has also been performed considering six different ORC working fluids and the changes in the direct normal irradiation of a city in Iran. In the trigeneration condition, the optimum values of the GT's compressor pressure ratio and ORC's turbine inlet pressure were obtained 9.06 and 3300 kPa, respectively. The exergy efficiency of the suggested system at the optimal condition is computed to be 14.40%, while that of energy is 40.52% with the total product cost rate of 30.524 $/GJ. The produced cooling capacity of the absorption system is also 1.62 MW whereas the output amount of freshwater and electricity for the users are about 5209.5 m3/day and 2.42 MW, respectively. The Levelized Cost of Electricity (LCoE) is also calculated to be 0.2341 $/kWh, which shows promising economic performance. [ABSTRACT FROM AUTHOR]