We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air is supplied to the room to ensure a dilution of airborne infection. Analyses of the flow in the room show that there are a number of parameters that play an important role in minimizing airborne cross-infection. The air flow rate to the room must be high, and the air distribution pattern can be designed to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed positions.

Air-borne bacteria in the operating room (OR) may contaminate the surgical wound, either by direct sedimentation from the air or indirectly, by contaminated sterile instruments. Reduced air contamination can be achieved with an efficient ventilation system. The current study assesses the additive effect of a mobile laminar airflow (MLAF) unit on the microbiological air quality in an OR supplied with turbulent-mixing air ventilation.

Precision ventilation is developed to achieve thermal comfort for occupants in an office by creating micro-climate zones. The present study aims to achieve individual thermal comfort for occupants with different metabolic rates by using higher airspeeds for enhancing heat transfer. The variable jet interaction between two ACBs with JetCone adjustments cause higher velocity jets to reach different regions of the occupied zone. The colliding jets from the center of a thermal isolated room were moved towards different zones in an office configuration with a constant room temperature of 23 °C. This study was conducted for five different cases in a room divided into four zones according to occupants’ metabolic rates. The experimental and CFD results show that occupants facing symmetrical airflow distribution and with a constant 1.2 metabolic rate (Case 1) had a similar predicted mean vote (PMV) index. The zones with higher-metabolic-rate occupants, i.e., 1.4 met and 1.6 met in cases 2 and 3 were exposed to air velocities up to 0.4 and 0.5 m/s, respectively. In case 4, the air velocity in the single zone with 1.6 met occupants was raised to 0.6 m/s by targeted airflow distribution achieved by adjusting JetCones. These occupants with higher metabolic rates were kept thermally neutral, in the −0.5 to +0.5 PMV range, by pushing the high velocity colliding jets from the center towards them. In case 5, the results showed that precision ventilation can maintain the individual thermal comfort of up to three different zones (in the same office space) by exposing the occupants with metabolic rates of 1.2, 1.4, and 1.6 met to airspeeds of 0.15, 0.45, and 0.55 m/s, respectively.

Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate turbulent mixing of the cold stream with ambient air. This study introduces the concept of precision ventilation for achieving local thermal comfort in a mixing ventilation system. This precision ventilation system provides asymmetrical airflows from an active chilled beam (ACB) to each of the office occupants. These ACBs provide air velocities with different magnitudes and directions. To achieve different magnitudes and directions, JetCones are used to vary the airflow in different parts of the ACB. The performance of the precision ventilation system was analyzed using full-scale laboratory experiments and computational fluid dynamic (CFD) simulations. The full-scale laboratory experiments were conducted in a 4.2 m × 3 m × 2.8 m (L × W × H) thermal isolated room with an open-plan dual desk-chair setup. The jet-cones in the ACB unit were adjusted to throw the required amount of flow to the occupants. The occupants had different metabolic rates of 1.2, 1.4, and 1.6 in a warm office space. The room set point temperatures varied between 23 and 26 °C. The experimental and CFD results show that occupants facing symmetrical airflow distribution and with a constant 1.2 metabolic rate had a similar PMV index. The occupants with 1.2, 1.4, and 1.6 metabolic rate were exposed to asymmetrical airflows, i.e., 30%, 58%, and 70% of the total airflow. Occupants with higher metabolic rates were kept thermally neutral, in the −0.5 to +0.5 PMV range, by increasing the air velocity and room temperature to 0.4 m/s and 25 °C, respectively.