Impact of green roofs on energy demand for cooling in Egyptian buildings

Energy consumption for cooling purposes has increased significantly in recent years, mainly due to population growth, urbanization, and climate change consequences. The situation can be mitigated by passive climate solutions to reduce energy consumption in buildings. This study investigated the effectiveness of the green roof concept in reducing energy demand for cooling in different climatic regions. The impact of several types of green roofing of varying thermal conductivity and soil depth on energy consumption for cooling school buildings in Egypt was examined. In a co-simulation approach, the efficiency of the proposed green roof types was evaluated using the Design-Builder software, and a cost analysis was performed for the best options. The results showed that the proposed green roof types saved between 31.61 and 39.74% of energy, on average. A green roof featuring a roof soil depth of 0.1 m and 0.9 W/m-K thermal conductivity exhibited higher efficiency in reducing energy than the other options tested. The decrease in air temperature due to green roofs in hot arid areas, which exceeded an average of 4 °C, was greater than that in other regions that were not as hot. In conclusion, green roofs were shown to be efficient in reducing energy consumption as compared with traditional roofs, especially in hot arid climates.Water ResourcesSanitary Engineerin

Use of insulation based on nanomaterials to improve energy efficiency of residential buildings in a hot desert climate

Building insulation based on nanomaterials is considered one of the most effective means of reducing energy consumption in the hot desert climate. The application of an energy-efficient insulation system can significantly decrease the energy consumed via a building’s air-conditioning system during the summer. Hence, building insulation has become an interesting research topic, especially with regards to the use of insulation based on nanomaterials due to their low U-values. In the present study, the use of nano vacuum insulation panels (VIPs) or polystyrene foam in the walls enabled a significant reduction in the annual energy consumption, a savings of 23% compared to the uninsulated wall in a study in New Aswan City. The application of nanogel glazing to the windows (two layers of clear glass filled with the nanogel) achieved approximately 11% savings in annual energy. This savings, twice that obtained by using double-glazed windows, could be due to the low U-value of nanogel compared to the U-values of argon or air. The embedded nanogel layer between two layers of argon and two layers of single clear glass showed a significant reduction in annual energy consumption, saving 26% compared to the use of a single layer of glass. Moreover, the integration between this window and embedded walls with 50 mm of polystyrene foam exhibited a significant improvement of energy efficiency by 47.6% while presenting the lowest value of simple payback period (SPP). This research provides a way for buildings to be insulated to make them more energy efficient as well as attractive from the economic standpoint.Water Resource

Enhanced strength, durability, and thermal shock resistance of clay roof tiles substituted with ferrosilicon slag

The present investigation involved the production of roof tile samples through the replacement of kaolin clay with varying proportions of Ferrosilicon slag (FS) (0%, 10%, 15%, 20%, and 25% by weight) at different firing temperatures (900 °C, 1000 °C, and 1100 °C). The present study investigated the impact of incorporating FS slag waste on durability, mechanical strength, thermal shock resistance, and thermal properties. Furthermore, an examination of the microstructure of the fired roof tiles was conducted through SEM analysis. The properties of the roof tiles exhibited enhancement as the percentage of FS slag increased, reaching a maximum of 15%, and the firing temperature increased up to 1000 °C. This can be attributed to the formation of significant amounts of corundum phase. Increased temperature and a higher percentage of FS slag are associated with the generation of a significant quantity of cristobalite phase, resulting in a reduction in the mechanical properties of roof tiles. The roof tile samples fabricated with up to 15% FS slag at 1000 °C exhibited low water absorption and porosity. Increases in temperature and FS slag, on the other hand, resulted in an increase in water absorption and porosity. There were no observable impacts on water absorption and apparent porosity at 900 °C. The firing temperature of 1000 °C and a slag percentage of 15% resulted in a minimum water absorption of 9.8%. This value meets the standard requirements for moderate weather resistance. Notwithstanding the increase in density of roof tiles containing elevated proportions of FS slag, they continue to fall within the limits of lightweight roof tiles as stipulated by determined standards. The experimental results indicate that the incorporation of 15% FS slag and firing at a temperature of 1000 °C resulted in a significant increase of 34.9% in the transverse breaking strength (TBS) of the clay roof tiles when compared to the conventional sample. This suggests that the structural properties of the clay roof tiles were improved through the addition of FS slag.Water Resource