Active chilled beams systems employ hydronic sensible cooling with low fan power, which makes them potentially more energy-efficient than the traditional air-based HVAC systems. Revision to ANSI/ASHRAE/ASHE Standard 170-2008, Ventilation of Health Care Facilities, allows recirculated air to be part of the total minimum air change rate requirements, which in turn allows the use of active chilled beams into patient rooms.
Active chilled beams (ACB) distribute cold supply air through linear diffusers and induce hot return air back into the cooling coil located inside the unit. Air is the primary carrier of heat, moisture, contaminants, and airborne pathogens in occupied spaces. Therefore, the distribution of supply air determines the resulting air velocities, temperature, and concentration of contaminants and airborne pathogens at various locations in a patient room. Such distribution in turn determines thermal comfort, air quality, and potential for transmission of airborne infectious pathogens in healthcare facilities such as patient rooms, isolation rooms, and operating rooms.