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Introduction The predicted mean vote (PMV) and predicted percent of dissatisfied (PPD) may be used to evaluate the thermal environment and thermal comfort (1),(2) and a number of thermal comfort [...]

Using thermal energy storage (TES) in phase change materials (PCMs) can reduce energy consumption in buildings. In summer, cold can be stored at night and released during the daytime therefore reducing the temperature while in winter, the system can be connected to a solar air collector that supplies heat. This article presents a paraffin based thermal storage unit and its annual operation. A 2D model is set up in Fluent, thereby calculating the thermal response of the unit. The cooling and heating modes along with a numerical analysis of different parameters are considered and the best ones are determined for the city of Ljubljana. [ABSTRACT FROM AUTHOR]

Detailed information of transient exhaled air dispersion and recirculation in the breathing zone can be obtained using computational fluid dynamics (CFD) to generate detailed numerical models and obtain the necessary information. In this study, interaction of free convection flow around human body with respiration flow of breathing and vertical personalized flow from personalized ventilation (PV) system was simulated using a commercial CFD package. Impact of breathing process on personal exposure effectiveness εp was evaluated for different operating and environmental conditions. Re-inhaled exposure index εRI for exhaled CO2 was used to assess the amount of exhaled air re-inhaled due to the interaction between personalized and exhaled airflows. Another objective of this study was to consider the risk of airborne infection transmission, caused by undesirable transport and dispersion of exhaled pathogens to surrounding air when infected individual uses PV. Results show that calculation of personal exposure effectiveness would be sufficiently accurate to give proper information about the protection of occupant with a PV system also without the breathing simulation included. The operating mode of a PV proved as the main factor for dispersion of exhaled air and its transport to the background room air, resulting in an increased risk of airborne infection transmission. [ABSTRACT FROM AUTHOR]

The article reflects on the capacity of engineers to excel in different fields such as material science, thermodynamics, and robotics. He notes how engineers can identify and assess the physical, mechanical, and other root causes of problems to aid derive to policies and engineering solutions. He stresses that the ability to address these challenges benefit from the continuing advances in analytical methods, material science, and computational fluid dynamics of structural engineering.

In the United States, K-12 school buildings spend more than $8 billion each year on energy--more than they spend on computers and textbooks combined [1]. Most occupied older buildings demonstrate poor operational performance--for instance, more than 30 percent of schools were built before 1960, and 53 percent of public schools need to spend money on repairs, renovations, and modernization to ensure that the schools' onsite buildings are in good overall condition. And among public schools with permanent buildings, the environmental factors in the permanent buildings have been rated as unsatisfactory or very unsatisfactory in 5 to 17 percent of them [2]. Indoor environment quality (IEQ) is one of the core issues addressed in the majority of sustainable building certification and design guidelines. Children spend a significant amount of time indoors in a school environment. And poor IEA can lead to sickness and absenteeism from school and eventually cause a decrease in student performance [3]. Different building types and their IEQ characteristics can be partly attributed to building age and construction materials. [4] Improving the energy performance of school buildings could result in the direct benefit of reduced utility costs and improving the indoor quality could improve the students' learning environment. Research also suggests that aging school facilities and inefficient equipment have a detrimental effect on academic performance that can be reversed when schools are upgraded. [5] Several studies have linked better lighting, thermal comfort, and air quality to higher test scores. [6, 7, 8] Another benefit of improving the energy efficiency of education buildings is the potential increase in market value through recognition of green building practice and labeling, such as that of a LEED or net zero energy building. In addition, because of their educational function, high-performance or energy-efficient buildings are particularly valuable for institution clients and local government. More and more high-performance buildings, net zero energy buildings, and positive energy buildings serve as living laboratories for educational purposes. Currently, educational/institutional buildings represent the largest portion of NZE (net zero energy) projects. Educational buildings comprise 36 percent of net zero buildings according to a 2014 National New Building Institute report. Of the 58 net zero energy educational buildings, 32 are used for kindergarten through grade 12 (K-12), 21 for higher education, and 5 for general education. [9] Finally, because educational buildings account for the third largest amount of building floor space in the United States, super energy-efficient educational buildings could provide other societal and economic benefits beyond the direct energy cost savings for three reasons: 1) educational buildings offer high visibility that can influence community members and the next generation of citizens, 2) success stories of the use of public funds that returns lower operating costs and healthier student learning environments provide documentation that can be used by others, and 3) this sector offers national and regional forums and associations to facilitate the transfer of best design and operational practices. [ABSTRACT FROM AUTHOR]

Background: Efficient production and reliable availability of electricity requires comprehensive understanding of load demand trends to plan and match production with consumption. Although electricity demand depends on a combination of cultural and economic conditions, weather conditions remain as the major driver. With increased capabilities of accurate predictions of weather, the importance of investigating and quantifying its impact on electricity demand becomes obvious. The electrical system in Jordan has been facing several challenges including the failure to respond to increased demands induced by extreme temperatures. This paper covers a clear gap in literature through presenting a detailed investigation of the electricity consumption trends and in identifying the susceptibility of these trends to weather. Methods: This study relies on the statistical processing and analysis, through modeling of hourly electricity demands in Jordan in the period of 10 years between 2007 and 2016. Actual weather data was used employing the degree-day approach. The monthly, daily, and hourly seasonal variation indices were determined. Optimally formulated piecewise functions were used to track the thermal comfort zone and rate of increase in electricity demand for temperatures beyond it for each year. Moreover, the elasticity of polynomial functions was adopted to identify saturation points to thermally map the electricity consumption. Results: The developed models successfully described the relationship between the daily electricity demand and the mean daily ambient temperature. The average comfort zone width was 4 °C and the average mean base temperature was 17.9 °C. The sensitivity of electricity demand to both high and low temperatures has increased on average, with 11% and 16.4% to hot and cold weather, respectively. Finally, the electricity demand in cooling was found to saturate at 32.9 °C, whereas it saturates for heating at 4.7 °C. Conclusions: The electricity demand in Jordan observes seasonal trends in a consistent and predictable manner. An optimally formulated piecewise function successfully tracked the thermal comfort zone and the rate of increase in electricity demand for temperatures beyond it for each year of the study period. Finally, saturation heating and cooling temperatures were acquired from the elasticity of the daily electricity demands modeled against daily HDD and CDD. [ABSTRACT FROM AUTHOR]