A B S T R A C TQuantifying incident solar radiation on a surface is a complex task that requires the knowledge of geometric, geographical, astronomical, physical and meteorological characteristics of the location.The aim of this paper is to analyze the attenuation processes of the solar radiation and to review the scientific works in this field, specifically the analytical models for solar irradiance calculation, as well as to establish an alternative method to compute the magnitude of the overall atmospheric transmittance.Analytical models have been developed since 1940 and they have been improving in precision and complexity. Up until now, the Bird & Hulstrom model is the most complete and accurate of them all. The main disadvantage of this model is that a great number of equations and parameters such as temperature, sunshine hours, humidity, etc. are required.In this paper, a very fast and accurate new method is developed to quantify solar irradiances at any site. The analysis shows that the parameters required are only the type of climate, altitude and state of the atmosphere. This method also allows to quantify the influence of the turbidity degree in both direct and diffuse irradiances. That information is essential to select which solar technologies are suitable in each place.As an application, the new method has been implemented and characterized in Mexico. Solar energy is an abundant resource in Mexico, and there are some studies about the solar energy potential in that country, but the influence of physical and meteorological factors on the solar radiation have not been related. In this study, the meteorological information of 74 weather stations located in different climates of the country were used to determine the parameters required. The results have been validated with experimental data available for different locations.

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Summary The worldwide environmentally friendly trend has focused the last decade on emphasizing the value of energy conservation and reducing the carbon footprint in buildings, achieving zero energy buildings. Presently, viable building techniques, in developing countries, are insufficient to achieve zero energy buildings. Thus, authorities should implement policies mandating new developments and renovations to establish “energy‐efficient buildings”; nevertheless, design solutions should be properly evaluated and assessed preceding execution. The conservation of energy without jeopardizing human comfortability is a huge challenge for any designer. Occupants are less interested in making a major investment to save some expenses over the next two decades, especially nowadays that energy is still affordable. Therefore, improved indoor environmental conditions are perhaps another important parameter toward energy‐efficient buildings. Through dynamic simulations, this study examines the energy efficiency and thermal comfort achieved by integrating retrofitting strategies in an institutional building in three different American Society of Heating, Refrigerating and Air‐Conditioning Engineers (ASHRAE) hot climate zones represented by three cities of Egypt (Aswan, Cairo, and Alexandria). The built‐up baseline model is validated using actual energy usage data. The validated baseline model is then subjected to local sensitivity analysis to determine the driving parameters influencing the building's energy demand. The study at hand focuses on a broader perspective on sustainability. With a multiapproach decision‐making methodology based on the most recent measures, the study highlights the outcomes through an environmental–economic assessment and indoor thermal comfort depending on experts' weighting, responses, and recommendations. The outcomes postulate that the implementation of reflective paints solutions would achieve the highest percentages of whole‐building energy savings with 21%, 19%, and 17% for Aswan, Cairo, and Alexandria, respectively, improving indoor thermal comfort levels.

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In this paper, an experimental and theoretical investigation is performed on a novel water desalination system based on a humidification–dehumidification technique using a heat pump. An ultrasonic water atomizer is used in the humidification process in order to improve the humidification system. In addition to that, a new configuration is employed in the humidification process (hybrid atomization system), which combines the traditional spraying atomization system and the ultrasonic water atomizer. The new humidification system performance is investigated and compared with the spraying water atomizer system in terms of humidification effectiveness and freshwater productivity. The results show that the ultrasonic water atomizer has enhanced and improved humidification effectiveness, and consequently, the productivity of freshwater. The maximum humidification effectiveness and productivity achieved by the ultrasonic water atomizer are 94.9% and 4.9 kg/h, respectively, meaning an increase of 25.2% and 18.8%, compared to the traditional spraying atomization system. The hybrid system increases humidification effectiveness and productivity by 3.8% and 8.2%, respectively, in comparison with the stand-alone ultrasonic water atomizer. A cost analysis was also carried out in this paper in order to perform an economic comparison of different humidification processes (spraying, ultrasonic; and hybrid atomization systems). The minimum production cost of one liter of freshwater amounts to $0.0311 with the spraying system, $0.0251 with the ultrasonic system, and $0.0250 with the hybrid atomization system. These results reveal the profitability of the new configuration.