IAQ APPLICATIONS Control Airflow Rate Damper Cooling Coil Outdoor Air Fan Filter AHU for the PV System Overhead Fan Coil Personalized Air is Supplied to all the Air Terminal Devices Fan Room Air Room Air Temperature Sensor Control qSUP Supply Air Temperature Sensor Exhaust Cleansed Air Sensors Drain Pan Polluted Air Drain Pan Control qUP Air Exhaust Through Leaks Room Air Figure 4: The principle of the HBIVCU ventilation method.10 Courtesy from “Ingeniøren.” Cleansed, filtered air is moved upward creating two air curtains and/or a horizontal air curtain preventing the airborne spread of pathogens. can be applied, providing flexibility in space use because patients in beds with HBIVCU can be moved from room to room. Figure 3: Improved environment and energy saving by coupling PV with mixing ventilation.8 Personalized Ventilation Combined With Mixing Ventilation The performance of desk installed PV combined with background TVAD used for room temperature control (Figure 3) has been studied in an office building located in a hot and humid climate (Singapore).8 The results obtained by simulation software reveal that the combined system may reduce energy consumption substantially (up to 51%) compared to mixing ventilation alone when the following control strategies are applied: a) reducing the airflow rate due to the higher ventilation effectiveness of PV; b) increasing the maximum allowed room air temperature due to PV’s capacity to control the microclimate; and c) supplying outdoor air only when the occupant is at the desk. Advanced Air Distribution in Hospitals Ventilation in hospitals is essential to decrease the risk of airborne cross-infection. At present, mixing air distribution at a minimum of 12 ach is used in infection wards (6 ach in patient rooms). The energy consumption and discomfort due to elevated velocity is high. Protection from airborne November 2011 cross-infection is inefficient because pathogens generated due to respiratory activities by infected patients are mixed with room air. A novel method for hospital ventilation based on AAD and exposure control has been reported. 9 It uses two devices, the hospital bed integrated ventilation and cleansing units (HBIVCU), which are attached to the patient’s bed (Figure 4). Polluted room air is pulled into the unit, cleaned (HEPA filter and UVGI light) and discharged horizontally over the patient to guide the exhaled/coughed air through the opening of the second device facing the patient before it is mixed with room air. The air is cleaned in the device and then either discharged upward to the exhaust as an air curtain (transparent barrier) between the patient and the person standing beside the bed, or it is discharged in the room, i.e., the device cleans the room air (not shown in Figure 4). The units can be connected to an existing air supply/exhaust system. The units reduce background ventilation rate and decrease the risk of airborne crossinfection. The “plug and play” principle www.info.hotims.com/37992-18 ASHRAE Journal 75