siliconindia | | AUGUST 20198THE FUTURE TREND IN BUILDING DESIGN TOWARDS MINIMIZING TRANSMISSION OF AIRBORNE INFECTIOUS DISEASESBy Prof. Chun CHEN, Assistant Professor - Department of Mechanical & Automation Engineering, The Chinese University of Hong KongHolding a Ph.D. degree from the School of Mechanical Engineering, Purdue University, Prof. Chun has profound knowledge of the engineering industry, with deep interests in the areas of indoor air quality, energy-efficient buildings, aerosol dynamics, and airborne infectious disease transmission.IN MY OPINIONT he transmission of airborne infectious dis-eases, such as avian flu, influenza, tubercu-losis and severe acute respiratory syndrome (SARS), has become a global public health issue. For example, the Spanish flu between 1918 & 1919 infected about one-quarter of the global population and killed more than 40 million peo-ple. Every year, influenza epidemics cause about 47,200 deaths in the U.S. In an estimation by The World Bank, a pandemic of avian flu among humans could cost the global economy $800 billion a year. The tuberculosis infections found in 22 countries and have caused 1.87 million deaths. During the SARS outbreak, there were more than 8,000 people infected globally. These airborne infectious diseas-es clearly have caused endless social and economic disrup-tions. Thus, it is crucial to understand and control the trans-mission of airborne infectious diseases in order to reduce their influence on human health.In recent decades, many outbreaks of airborne infec-tious diseases have occurred in buildings where people spend most of their time. An infected person can exhale droplets containing infectious viruses through breathing, coughing or sneezing. These airborne droplets can be trans-ported to the breathing zones of other persons via the air in the buildings. If the susceptible individuals inhale these droplets, cross infection of the disease may occur. These transmission routes indicate that the air distribution in buildings can play a significant role in the transport of air-borne exhaled droplets. If the airflow can directly remove the exhaled droplets from the room or block the transmis-sion route to the breathing zones of other occupants, the infection risks can be minimized. Therefore, it is crucial to carefully design the airflow distribution in buildings in or-der to reduce the airborne infectious disease transmission. The most conventional air distribution mode in build-ings is that of mixing ventilation. Both the supply air dif-fusers and exhausts are usually installed at the ceiling level. The conditioned air with fresh air is supplied to the room. Due to the strong supply air jets, the air is well mixed in the room so that the fresh air can reach to the whole space. However, as the air in the room is well mixed, when an in-fected person exhales droplets, these droplets can be trans-Chun CHEN
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