In Iran, some 22 percent of the building energy dissipates through the roof. In the hot arid parts of the country, most of this energy is used for cooling rather than heating. There are several methods for reducingthis energy loss. Insulation is one popular method throughout the world. A more effective method is to reduce the energy penetrating the building by means of cooling the roof. There are three main techniques for obtaining a “cool roof”. In the first method, heat loads are reduced by lightening the color of the roof, hence increasing its albedo. In the second method, the “green roof”, the roof is suffused with vegetation, which is more expensive and technically complicated. In the third method, the roof is sprinkled with water. In this method, a significant amount of water is wasted, however. Because of its inexpensiveness and simplicity, the first method was chosen for an experiment, in which part of a dark green roof was repainted with brilliant light green. The daily summer temperatures were then measured on an hourly basis and compared with the shaded areas of the roof as well as areas covered by plants. The results indicated that the repainted areas were about 17 percent cooler.

The unfavorable consequences of the expansion of the metropolitans, including urban heat island and air pollution, have attracted the attention of urban managers to strategies for improving environmental conditions. In recent years, along with population growth and high energy consumption, as well as building materials replacing permeable surfaces and urban green spaces, deteriorate the urban heat island phenomenon and air quality in Tehran. Given the significant area of roof surfaces in urban areas, the application of new and environmentally friendly technologies such as the development of cool and green roofs, with heat island modification impact, can play a positive role in reducing cooling energy consumption and improving air quality. Therefore, to study the mutual interaction between meteorological parameters and changes in the urban structure and its possible side effects on air quality, numerical simulation of green roof and cool roof strategies based on the urbanized coupled meteorological-chemical model (WRF/Chem/SLUCM) during the period June 15 to 30, 2016, have been conducted in Tehran metropolitan area. Results show that the development of cool roofs with an averaged diurnal temperature decrease (-0. 65° C) and a decrease in the heat flux (-57 W/m2) has a positive role in the reduction of Tehran heat island. Also, the relative reduction of atmospheric pollutant concentrations has also been achieved in numerical simulations. It shows that the decrease in the height of the boundary layer and turbulence process as a result of the decrease in near-surface temperature has not caused a significant change in the air quality in Tehran. The development of green roofs has led to a daily (nightly) decrease (increase) in the air temperature. The increase in temperature during the night was noticeable (up to +0. 53° C), and it is a result of the high emissivity of vegetation, as well as a decrease in wind speed in the vicinity of green roof surfaces which slows down the natural ventilation over the city. Furthermore, an increase in the near-surface humidity also predicted in both strategies which improves the environmental comfort satisfaction in the summer hot and dry days. Comparison of these strategies performance shows that cool roof has a significantly sensible cooling effect than green roofs, and the process of reducing pollutants, especially at night, is more favorable in cool roofing strategy. Consequently, since the cooling efficiency of green roofs depends on soil moisture content, as well as comparing construction costs and no need for specific infrastructure, the development of cool roofs in Tehran metropolis is recommended.

cooling and heating energy accounts for a significant portion of the total energy consumption in residential sector. Building envelope is exposed to sunlight and outside air and therefore have a significant role in determining the thermal loads of buildings. Meanwhile, roofs which are exposed to sunlight all the day long are important envelope components and have a significant share of buildings energy consumption. Therefore, applying appropriate roof solutions can significantly reduce building energy consumption for air-conditioning and improve indoor comfort conditions. This paper aims to investigate the effect of different roofing techniques on thermal performance of a single-storey residential building with two types of uninsulated and insulated configurations under different climatic conditions of Iran. For this purpose, different cool roof albedos 0. 5, 0. 7, and 0. 9 and two types of green roofs, GR with actual local rainfall and wet GR, are considered. The thermal loads of the buildings are calculated using the DesignBuilder software and compared with a conventional cast concrete roof. The results show that by choosing an appropriate type of roof technique, the total air-conditioning energy requirement of the building can be reduced between 7-31%, depending on the building configuration and climatic condition.

Background and Objectives Uncontrolled bleeding is the first leading cause of preventable death in the battlefield and the second cause of mortality in civil accidents. Incompressible hemorrhage control is among the interventions that drastically increase the survival rate of the wounded individuals.Materials and Methods Three healthy hybrid dogs were selected and after induction of anesthesia with Ether, either arterial puncture by a needle or arteriotomy was performed on both groin regions of the dogs.For control arteries, only a 4 min pressure using a sterile gauze was performed, while for the femoral arteries of the opposite side, cool Clot hemostatic agent was topically used before the pressure. To assess the Coagulation Time (CT), blood samples were collected from 10 volunteer students. CT was measured by a chronometer according to standard Lee -White method.Results In dog animal model, the Bleeding Time (BT) in control arteries (no hemostatic agent) was more than 15 minutes, while in case of the opposite sides which were treated with cool Clot hemostatic agent, the BT was only up to 5 minutes. In the human phase of the study, the mean coagulation time in control blood samples was 253.4±4.1 sec, while for blood samples treated with bentonite, zeolite and cool Clot the mean times were 149.5±50.0, 162.3±74.5 and 143.4±114.6 sec, respectively.Conclusions The results obtained in this study indicate the significant efficacy of cool Clot in shortening the BT in dog model or CT in human blood samples.

First roof weighting interval in mechanized longwall mining is related directly to the applied loads on support system and thus, has important role on stability, safety, and continuity of operation. This paper presents an innovative approach based on cavability of immediate roof to estimate first roof weighting interval. Nine inherent parameters of roof strata and its surrounding environment which affect caving process were taken into account to develop a classification system, incorporating fuzzy hybrid multi criteria decision-making technique. roof Strata Cavability index (RSCi) was defined as summation of ratings for all parameters. Subsequently, the relationship between RSCi and extracted volume until the first caving moment (i. e. the extraction height× panel width × first roof weighting interval) was determined using linear and non-linear regression models. Models were proposed and validated using the actual field data collected from different longwall panels around the world. Results indicated that the quadratic polynomial model gave a better performance in the estimation of first roof weighting interval, compared to the other models. It was concluded that the proposed approach is an accurate and flexible tool to estimate first roof weighting interval in longwall mining.

Global warming can increase urban temperatures by up to 10 °C, with significant health, environmental and energy implications. The materials of the building and urban fabric have an impact on the thermal balance of the city and significantly increase the risk of urban warming. This review describes advances in the design, manufacture and application of ultra-low and low surface temperature coatings for buildings and equipment. It covers the definitions, mechanisms, evaluations, and recent technological advances of natural, light-colored, infrared solar reflective, PCM-doped, thermochromic, quantum dot, and plasmonic cool materials. A comparative analysis of the experimental results on the cooling capacity and thermal performance of the traditional or new materials is provided. It is shown that natural cool coatings can reflect 80-90 % of solar energy and save 18 % of cooling energy, white and colored cool pigments can exhibit 85-95 % solar reflectance, and novel cool materials can reflect more than 93 % of solar thermal energy. In addition, PCM-doped cool coatings can reduce the surface temperature by 2.5 to 19.7 °C. The aim is to present the best method among those proposed in terms of energy and raw material cost for cool coatings. This review also explains how cool coatings with high solar reflectance can absorb less solar energy and increase the lifetime and efficiency of power systems and electronic devices that are typically exposed to sunlight.

roof tiles are the most common roof coverings in Indian buildings, especially in traditional residential buildings. Given the important role of roofing characteristics in building energy efficiency and indoor thermal comfort conditions, innovative solutions to improve the thermal energy performance of this diffused roofing element have become a key research issue. In this perspective, cool roofing applications represent an effective solution to this objective. The present work deals with the analysis of innovative cooling roof tile manufactured using a combination of Metakaolin with different percentages, EPS, sodium silicate and coating material. The experimental work was carried out during day and night. The thermal performance of cool roof tiles were assessed in terms of the open-air temperature compared to the thermal performance of ordinary roofing tile. The report discovered that using revolutionary cool roofs greatly increased thermal comfort during the daytime, and preserved thermal comfort during the night. The innovative cool roof tile is cheaper, easier to implement, and less expensive compared to other roofing technologies. The study revealed that the roof's exterior and interior surface temperature reduced about 8°C and 12°C, respectively during day time, while roof's exterior and interior surface temperature maintain atmospheric temperature during night time. The compressive and transverse breaking strength was increasing about 9.1% and 39.6%.