The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate. Installing partitions between the beds and changing the ventilation system’s inlet and outlet diffuser positions contributed only minimally to reducing the concentration of airborne pathogens.
This paper aims to derive the operational modes of a parallel double-window system that reduces cooling energy consumption and satisfies indoor comfort through natural ventilation. The parallel double-window system examined in this paper is a window system that could control indoor draft distribution and adjust the size of the opening depending on indoor and outdoor conditions. The system can be used in five ways (all close, out-open + in close, out-open+in open (tilt), out-open+in open (turn) and all open). This work verified the energy savings and indoor comfort of the existing mode experimentally, which were originally derived based on simple calculations at the time when the parallel double-window system was developed. A new operation mode, Alt 1, was derived, which addressed problems of the existing mode. In addition, in this work, the operation mode Alt 2 was derived, which simplified Alt 1 so that the actual occupant can use the system easily. By measuring these three operation modes and comparing the results with those of energy plus simulations, the work derived the amount of cooling energy savings and the level of indoor comfort through the use of an appropriate operation mode during inter-seasonal periods. Compared to when the natural ventilation operation mode was not used, cooling energy consumption was reduced by 60% when the operation mode was in use. The cooling temperature set point could have a significant impact on cooling energy consumption.
This study investigated design recommendations to reduce airborne infection risk in an emergency department by using airflow network simulation. The main design concepts include isolating the source of the airborne pathogen and increasing the ventilation rate. A conventional emergency department is selected as a base model, and influenza is selected as the airborne pathogen examined in the study. The Wells-Riley equation is used to model airborne infection risk in a zone. The simulation results indicate that airborne infection risk exists when a patient releases an influenza pathogen in the emergency department with a ventilation rate of 3 ACH according to the Korean building code. The findings reveal that isolating the airborne pathogen source and increasing the ventilation rate are good methods to prevent airborne infection risk. However, the isolation method can increase the infection risk in a zone with an airborne pathogen source. Thus, it is necessary to simultaneously increase the ventilation in a zone with an airborne pathogen source. Additionally, airborne infection risk continuously increases the cumulative exposure time, and it is desirable to increase the ventilation rate required for a zone based on the residing time of a patient releasing airborne pathogens in a target zone.
In the recent years, the spread of food odour in highrise residential buildings has become a serious factor in indoor air quality problems in Korea. This study examined the use of ventilation systems to reduce the transmission of odour in the high rise buildings. The spread of food odour in an existing residential building was analysed by measurement and computational fluid dynamics (CFD) simulation. Although the kitchen exhaust system was used during cooking, the food odour level was ''strong'' in the kitchen and in the living room, and its spread caused the most serious problems at mealtimes. The existing system needed modification to reduce the food odour spread. The ventilation system in the kitchen was improved by increasing the volume of air exhausted through the ceiling, by changing the supply inlet's angle of incidence, and by fitting a stronger exhaust system with the ability to decrease the food odour level in a shorter time. During development, system performances were analysed using a CFD simulation method. The food odour level was shown to have decreased greatly by the use of the modified kitchen exhaust system, which reduced the food odour to below the ''weak'' level in 30 min.
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