In many countries, there is a growing interest in utilizing passive and low energy systems tor heating and Cooling of buildings. Electricity consumption associated with air conditioning systems in buildings, makes serious problems Such as nonrenewable resource dimination and environmental pollution.Based on the geographical location at Iran which is mostly located in a semi-arid climate, applying an evaporative Cooling system could be a useful idea.This paper is concentrated on the performance at some passive evaporative Cooling systems.

Global crises in terms of energy, environment and health are among the major challenges which human being is facing nowadays. According to these problems, architects and building designers are making major attempt to minimize nonrenewable energy consumption in buildings. They seek various ways to reduce negative impacts of building on environment while providing comfort and health for building occupants. Therefore designers are making attention to use renewable energy resources in buildings. passive systems of energy are among the most effective methods in providing thermal comfort requirements of building occupants. Taking advantages of the local climate and site potentials, such systems make use of renewable sources of energy. Environmental sustainability could be considered as the main advantage of such systems which could be classified in the two groups as passive heating and passive Cooling systems. In Iranian architecture passive Cooling systems had been used for many years according to the hot climate. Therefor various architectural elements have been used in vernacular buildings of Iran. This article describes the principles of each passive Cooling system, introducing various methods to control building thermal behavior. Based on the same basics, these principles have been used in contemporary elements with new forms. Describing each vernacular element, the contemporary corresponding system or element has been introduced.

Photovoltaic panels’ performance is degraded when their temperature rises above 25 . Various Cooling methods are proposed to deal with this issue. In this study pin fin Cooling is introduced as a simple and cost-effective passive Cooling technique to cool a 10 (W) monocrystalline photovoltaic module. Indoor experimental tests have been conducted to investigate the module’s thermal and electrical performance. Based on the radiation intensity, module’s tilt angle, pin fin numbers, and pin fin arrangements, four categories are defined and extensively studied. The obtained results reveal that adding pin fins can reduce the module’s temperature up to nearly 10 . More interestingly, by inclining the bare photovoltaic module from a horizontal state to a 45-degree inclination angle the module’s average temperature is reduced by 6 . This temperature reduction is about 15  if the PV module is inclined by 45 degrees and also attached by 100 pin fins. Based on the experimental findings, the change in the pin fins’ arrangement did not show a sensible change in either thermal or electrical performance of the photovoltaic device.

The rapid growth of global population has placed an immense stress on the demand of natural resources and contributes to the destruction of the natural environment. As the planet is now consuming natural resources in the production of goods and services faster than the environment can regenerate, strategies are urgently required to manage the ecological assets in a more effective way. The planet has biophysical limits on natural resources production and waste absorption. Buildings are one of the main factors in energy consumption and greenhouse gas emissions. Buildings consume about 40% of global energy consumption. All building services such as heating, ventilation, and air conditioning (HVAC) systems consume more than 60% energy in buildings, which is mainly supplied by fossil resources. Today, because of the need for an effective method to achieve efficient energy and biocompatible architecture, the use of natural ventilation systems in buildings has become more significant. One of the methods to create comfortable conditions in the interior is a use of evaporative Cooling in the Cooling systems. Unlike air conditioners, evaporative Cooling can be considered as an acceptable solution for sustainable construction, which reduces energy consumption and greenhouse gases. Evaporative Cooling is widely used as a passive Cooling method in the built environment. In the system, the movement of air on a wet surface causes the water evaporation through the air energy absorption, thereby reducing the temperature and increasing the amount of vapor contained in the air. We need indicators to demonstrate the current carrying capacity of the Earth so that decision makers are better informed to set goals, establish options for actions, and monitor progress regarding stated goals. Footprint is a quantitative measurement of natural resources and it is used to assess the extent of human activities impact on global sustainability. Ecological footprint was initially developed by Wackernagel and Rees in 1992, and is now widely used as an indicator for environmental sustainability. The international average water footprint is 7452(〖 Gm〗 ^3⁄ year) and this amount is reported to be 102/65(〖 Gm〗 ^3⁄ year) for Iran. The aim of this study is to design a passive Cooling system to provide comfortable conditions in residential Buildings. Also, with minimal water and electricity consumption, it will reduce ecological footprints and water footprints and also reduce the amount of electricity consumption in the building. This research was done experimentally-analytically. In order to calculate the efficiency of the proposed system, on August 4th to 7th, the temperature, humidity, and wind speed of the interior room were measured by considering the system. The Hybrid passive Cooling System (HPCS) consisted of two distinctive systems: the Solar Chimney (SC) and Evaporative Cooling Cavity (ECC). The ECC system was connected to the northern view of the room and SC system was installed to the southern view of the room. The air entered the tower via the openings of the head tower in all directions and passed through the clay cylinders. In this section, the air is cooled and diverted downward. The SC system creates sufficient temperature difference between the interior and exterior by maximizing the solar energy gain and performed air ventilation in the SC and ECC systems. The proposed hybrid system was built in the campus of Azad University, Kermanshah branch in August and was tested from August 4th to 7th. In order to calculate the efficiency of the proposed system, on August 4th to 7th, the temperature, humidity, and wind speed of the interior room were measured by considering the HPCS. To evaluate the water consumption of the HPCS, two scenarios were considered and their results were compared with each other. Scenario (1): on August 4th-7th, the amount of water reduction inside the clay cylinders was measured from 9: 00 AM to 3: 00 PM. Scenario (2): On August 18, the room temperature and humidity were measured from 9: 00 AM to 3: 00 PM. Based on the results, Cool performance of HPCS: the lowest temperature was recorded 21. 1 ° C at 9: 00 AM on the 5th of August. The lowest temperature is noon on 22. 9℃ and on the 6th of August. At 3 PM, the lowest air temperature of 23. 72 was reached on the 5th of August. The highest difference between the temperature of the inlet windcatcher and the outside environment is 16. 3℃ , which is on the 7th of August and at 3: 00 PM. the ECC system can increase the RH of air by an average of 34 %. the highest outlet air velocity of the tower is 0. 72 m⁄ s, at 3: 00 PM on the 5th of August. The lowest air velocity is 0. 5 m⁄ s at 9: 00 AM on the 6th of August. Water and electricity consumption of evaporative cooler in scenario 2: To investigate scenario 2, on August 18, the temperature and humidity inside the room and the outside environment were measured from 9: 00 AM to 3: 00 PM. The lowest and highest levels of indoor humidity are 16% at 3 PM and 27% at Noon, respectively, while the outdoor humidity is 13% at 3 PM and 19% at 12 Noon. The evaporative cooler lowers the indoor ambient temperature by an average of 5% and increases the ambient humidity by an average of 7%. Comparison of electricity and water used in scenarios 1 and 2: The amount of electricity consumed in Scenario 1 is zero, but in Scenario 2, this value is 12112. 9 kJ per day. The environmental footprint of electricity consumed in Scenario 1 is zero, but in Scenario 2, it is 1. 05 Gigabits per year. The water used in Scenario 2 is 0. 04 m^3more than Scenario 1. The results showed that the chamber can provide comfort conditions with zero energy consumption by using a hybrid system during the hottest days of the year from 9: 00 AM to 3: 00 PM. The power consumption of the evaporative cooler in the 3 months of summer is 1. 13 GJ, while the power consumption of the designed hybrid system is zero. The ecological footprint of the power consumption of this system is zero, while the ecological footprint of the evaporative cooler is 1. 05(Gj⁄ year). From the data obtained, we conclude that the passive hybrid Cooling system has the lowest ecological footprint of water and electricity compared to evaporative coolers. The system is also able to provide indoor comfort on the hottest days of the year.

The Cooling energy has covered most portion of building energy consumption in hot and arid climates. Accordingly, suppling of required energy for Cooling systems as well as passive solutions to reduce air temperature are so noticeable. As an effective factor, Phase change materials through changing phase save energy and help to improve natural ventilation as well as thermal comfort. These materials have various types base on their chemical structure and melting point. In this way, optimal PCM selection base on their application and melting point is very important; so that, improve natural ventilation and Cooling energy in buildings. This study investigates the properties and behavior of phase change materials for their implementation in building passive Cooling systems as well as natural ventilation by reviewing and analyzing valid researches and documents in hot and dry climate of Yazd city. Finally, due to PCMs type, their application, and climate condition, optimal PCM has been found; so that, provide thermal comfort, energy consumption reduction, and natural ventilation. As a result, PCM with melting point of 28 ° C can put the environmental temperature in the thermal comfort zone; besides, improve thermal comfort conditions and natural ventilation.

High temperature is one the important factor that degrades efficiency of Photovoltaic Panels. For every degree increase in the PV temperature, the efficiency decreases by 0.45-0.65%. The Enhancement of performance of flexible PV panel using passive Cooling Technique is the main goal of this study. The research aims to optimize the power conversion efficiency of flexible PV panels which are highly affected due to direct contact of mounting surface making them overheat, resulting in decreased output and lifespan. In the present study, two Identical Flexible PV panels 6W each were tested at optimum tilt angle of 31o in atmospheric condition in hot and dry climate of Jodhpur (26.2697°N,73.0352°E), India. Here different electrical parameters of passively cooled panel using Nanomaterial based heat resistant coating were compared with those of a reference panel that lacked Cooling. Also, temperature variations over the PV modules were meticulously recorded during August, September, and October using temperature sensors, while considering influencing factors such as wind speed and solar irradiation. According to Experimentation’s finding, a temperature reduction of 6-7°C and an improved solar power efficiency of 2.5-4 % were observed for cooled flexible solar panel.

Nowadays, a high amount of energy is used for ventilation, Cooling, and heating of buildings. Using clean and natural energy is one of the best ways to reduce energy consumption in buildings. Using the passive approach as a non-mechanical method is an effective technique to deal with high energy consumption. Also, underground and semi-underground buildings are some of the most productive Iranian traditional structures that include the category of passive Cooling and are very useful in hot and dry and hot and humid areas. The range of temperature fluctuations in the depths of the earth is much lower than that in its surface layers, so the temperature is almost stable and equal to the annual mean temperature of the earth's surface at depths below 6 meters. Thus, the purpose of this study is to review the studies conducted in this field, specifically those that have investigated the types of underground structures and their Cooling potentials. Also, it aims at finding the gaps in these studies and determining the underground structure that needs more detailed studies. The research method in this study is descriptive and analytical. The results revealed that passive Cooling strategies and related techniques can be classified based on the performance of underground structures. These strategies are sometimes used in combination. The results also revealed that it is possible to provide the conditions for modernization for some of these structures. However, these elements such as aqueducts and Yakhchals have been further studied and developed.

The issue of thermal comfort, especially Cooling, is highly significant due to the role that it plays in sustaining the environment and climate. Indeed, thermal comfort is the main constituent of vernacular architecture in all regions. Shelter as a man-made development, has taken climate into consideration in the form of passive Cooling and heating throughout history.In spite of its significance, the issue of climate has been ignored in the past century. It can be argued that the purpose of construction is livelihood. In an urban context, thermal comfort comes alongside architectural development.In this paper, the indigenous architecture of different regions has been analyzed and the physical features of earth in arid and tropical climates have been compared with one another.By considering the climatic classification, and in order to achieve appropriate techniques for Cooling by passive means by using the earth mass, several vernacular architectural structures have been examined.

A B S T R A C T Temperature is one of the climate elements that has fluctuated a lot over time. When these fluctuations increase and decrease more than normal and are placed in the upper and lower regions of the statistical distribution, if continued, it can lead to the creation of heating and Cooling waves. The purpose of this study is to analyze the temporal and spatial changes in heating and Cooling waves in Iran during a period of 50 years. For this purpose, the temperature of 663 synoptic stations from 1962 to 2004 was obtained from the Esfazari database. Then, in order to complete this database, the daily temperature from 2004 to 2011 was obtained from the Meteorological Organization of the country and added to the aforementioned database. In order to perform calculations and draw maps, Matlab, grads and Surfer software have been used. The results of this study showed that the index of Cooling waves and heating waves, while having a direct effect on each other, had an increasing trend in most of the area of Iran. The statistical distribution of the index of Cooling waves is more heterogeneous than that of the index of heating waves. So that the spatial variation coefficient for cold waves is 84.22%. Also, the index of Cooling waves has more spatial variability. The highest common diffraction of the index of heating and Cooling waves has been seen in the northwest, east and along the Zagros mountains. Analysis of the indexes trends show that heat waves have intensified in 65.8% of Iran and the intensity of cold waves has decreased in 48.5% of Iran Extended Abstract Introduction Temperature is one of the major climatic variables, which it has a direct impact on different aspects of human life. It plays an essential role in the growth of crops and is considered a key driver of the biological system(Reicosky et al, 1988). It is associated with several types of extremes, for example, heat and cold waves which caused human societies maximum damage. Past occurrences of heat waves hitherto had significant impacts on several aspects of society. Have increased Mortality and morbidity. Ecosystems can be affected, as well as increased pressure on infrastructures that support society, such as water, transportation, and energy(Dewce, 2016). The long-term change of extreme temperatures has a key role in climatic change. The form of statistical distribution and the variability of mean values and also extreme event indicate a change in the region. It can be a small relative change in the mean as a result of a large change in the probability of extreme occurrence. Also, the variation in temperature data variance is significantly more important than the mean, for assessing the extreme occurrence of climate(Toreti and Desiato, 2008). The average surface temperature has increased the world between 0.56 and 0.92 ° C over the past 100 years(IPCC, 2007). Meanwhile, it was in the Middle East, the average daily temperature increased by 0.4-0.5 ° C in decades(Kostopoulou et al, 2014; Tanarhte et al, 2012). Considering that not many studies have been done in the field of spatio-temporal Variations of the heating and Cooling waves thresholds in Iran, in this study, the spatio-temporal Variations of the heating and Cooling waves thresholds in Iran during 50 years were examined and analyzed.   Methodology The daily temperature from the beginning of the year 21/03/1967 to 19/05/2005 was obtained from the Esfazari database prepared by Dr. Masoudian at the University of Isfahan. In order to increase the time resolution of the mentioned database, the daily temperature of observations from 05/21/2005 to 05/12/2012 has been added to the mentioned database using the same method, and the exact spatial resolution (15 x 15 km) is used as a database. Threshold indices of heating waves are the average numbers between the 95th and 99th percentiles, that is, the extreme hot threshold to the limit of excessively extreme hot. For extreme cool, from the 5th percentile down to zero is used. Of course, a condition was added to these thresholds, which is that these thresholds must be repeated two days in a row. These thresholds were extracted for each day in the 50 years of the study period and used as the original database. In order to analyze the relationship between Cooling and heating waves, Pearson's correlation coefficient was used and regression was used to analyze the trend.   Results and discussion The average of cold waves was 5.26 ° C and for the heat waves is 30.20° C. Generally, if the temperature is upper or lower than this threshold, it is considered as hot or cold temperatures. A comparison of the median, mode, and average of cold waves with heat waves shows that the distribution is more heterogeneous for cold waves and its CV is 84.22%. In southern Iran, the average threshold heat waves are higher. This situation can be caused by the effects of subtropical high-pressure radiation, low latitude, and proximity to the sea. Though the threshold is higher in these areas, fewer fluctuations and changes are seen in the area. Heights moderate the temperature so they pose a minimum threshold for heat waves i.e. an iso-threshold of 25 ° C is consistent along the Zagros mountain chains, but in the west and east of Zagros Mountains, the threshold of heat waves is increased. Heat waves have increased in most areas of the country. So nearly 85 percent of the Iran has been an increasing trend, of which 65.8 percent is statistically significant at the 95% confidence level. Still, more areas of the country (60 percent) have a trend between 0.00828 and 0.00161. As can be seen, only 15% of the land area (including the southwest and northwest of the Country) had decreased heat waves. Cold waves, in most parts of the country, have a Positive Trend. However, about 25 percent of the study area's cold waves have a negative trend. they are located in areas higher than Latitude 30°. The largest decline of the wave's trend along the country is highlands. Nowadays, most of the country, has a trend between 0.01494 and 0.00828 ° C, respectively. Conclusion Common changes and effects of heat and cold waves had a direct relationship in many parts of the country. It is remarkable common variance in the East reached 55 percent, according to statistical significance. In some areas of the northwest and southwest, which have been impressive heights, the common variance is 40 percent. This common variance in mountains area has been high values. Investigation of heat waves trend shows that 65.8% of Iran significant positive trend and 7.1% significant negative trend. Also, the cold waves trend has indicated a 48.5% significant positive trend and a 10.8% significant negative trend. Climate change and global warming have changed the frequency and severity of temperature extremes. The present study, by examining the number of warm waves, concluded that the warm waves have increased in magnitude in 65.8% of the Iran zone. Also, the study of the cold waves trend showed that 48.5 percent of Iran had a positive trend, which means that the amount of temperature in the cold waves increased In other words, the severity of the cold has been reduced And only 10.8 percent of Iran had a negative cold wave trend And it shows the intensity of these waves is reduced.   Funding There is no funding support.   Authors’ Contribution The authors contributed equally to the conceptualization and writing of the article. All of the authors approthe contenttent of the manuscript and agreed on all aspects of the work declaration of competing interest none.   Conflict of Interest The authors declared no conflict of interest.   Acknowledgments  We are grateful to all the scientific consultants of this paper.